1. A shear force-based droplet generation device (100) operable in a submerged fluid environment, comprising: a base (110) extending along an x-axis, a y-axis, and a z-axis; a first dispenser (112) arranged on the base, the first dispenser comprising a first nozzle (114) oriented along the y-axis and adapted to dispense a primary droplet (116) of a first fluid (118) in a dispersed phase via a syringe pump (120) fluidically connected to the first dispenser, wherein the primary droplet dispenses off from the first nozzle along the y-axis in the submerged environment; a pressurised fluid source (122) configured to store a second fluid (124); a pressuring device (126) operatively connected to the pressurised fluid source to increase the pressure of the second fluid; a second dispenser (130) fluidically connected to the pressurised fluid source and arranged on the base at a predefined distance (112D) from the first dispenser along the x-axis, the second dispenser comprising a second nozzle (132) oriented at a predefined angle (134) relative to the first nozzle in a cross-flow configuration, wherein the second nozzle is adapted to dispense a micro-jet (136) of the high pressure second fluid towards the primary droplet of the first fluid, and wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween; a regulating valve (138) arranged between the second dispenser and the pressurised fluid source, the regulating valve adapted to control a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser; and a processor (140) operatively connected to the pressuring device and the regulating valve, and configured to operate the regulating valve to dispense the micro-jet of the high pressure second fluid upon a surface region (142) of the primary droplet, when a radius (116R) of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet to pinch off the primary droplet from the first dispenser.

2. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the processor (140) is configured to control at least one operating parameter associated with an interaction between the micro-jet (136) of the high pressure second fluid (124) and the primary droplet to maintain a Weber number for switching between modes of pinching off the primary droplet (116), wherein the modes of pinching off comprises: a first mode to pinch off the primary droplet into a single-droplet formation, when the weber number is less than 11; a second mode to pinch off the primary droplet into a multi-droplet formation, when the weber number is between 11 and 350; and a third mode to pinch off the primary droplet into a spray formation, when the weber number is more than 350.

3. The shear force-based droplet generation device (100) as claimed in claim 1, further comprising a first holder (302) having a first axis (304) and configured to receive the first dispenser (112) therein, a second holder (306) having a second axis (308) and configured to receive the second dispenser (130) therein, wherein the first holder and the second holder are arranged on the base (110), and a relative positioning of the first dispenser and the second dispenser is adjustable along at least one of the x-axis and the y-axis on the base.

4. The shear force-based droplet generation device (100) as claimed in claim 3, wherein the adjustable relative positioning comprises adjustment of at least one of: a first offset (310) between the first axis (304) and the second axis (308) along the x-axis and a second offset (312) between the first axis (304) and the second axis (308) along the y-axis, wherein adjustment of the first offset (310) shifts a location at which the micro-jet (136) interacts with the primary droplet (116) along the y-axis, and wherein adjustment of the second offset shifts the location of interaction along the x-axis.

5. The shear force-based droplet generation device (100) as claimed in claim 1, wherein a diameter of the primary droplet (116) pinched off from the first dispenser (112) is in a range of 500 micrometres (μm) to 5 millimetres.

6. The shear force-based droplet generation device (100) as claimed in claim 1, wherein an orientation of the first dispenser (112) is adjustable to control a direction of movement of the primary droplet (116) along the y-axis.

7. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the first fluid (118) is a non-Newtonian or a complex fluid.

8. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the predefined angle (134) is between a range of 11 to 100 degrees.

9. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a storage tank externally pressurized using a compressed fluid, and wherein the regulating valve (138) comprises a solenoid valve, such that a pressure within the storage tank and an opening duration of the solenoid valve are controllable to modulate a strength of the micro-jet (136).

10. The shear force-based droplet generation device (100) as claimed in claim 9, wherein the processor (140) is operatively connected to the pressurised fluid source (122) and the regulating valve (138) to control pressurisation of the second fluid (124) and actuation of the regulating valve for modulating the strength of the micro-jet (136).

11. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a pump disposed downstream of the pressurised fluid source, and wherein the regulating valve (138) comprises a flow control valve disposed downstream of the pump, such that operation of the pump according to predefined timings and adjustment of the flow control valve to control a flow rate of the fluid and thereby modulate a strength of the micro-jet (136).

12. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a piston-cylinder arrangement configured as a positive displacement pump, the piston being operable using a motorised arrangement or manually, such that a flow rate of the second fluid and thereby a strength of the micro-jet (136) are adjustable by varying a piston velocity and a stroke length.

13. A method for a shear force-based droplet generation in a submerged fluid environment, comprising: arranging a first dispenser (112) on a base (110) extending along an x-axis, a y-axis, and a z-axis; adapting a first nozzle (114) of the first dispenser arranged along the y-axis for dispensing a primary droplet (116) of a first fluid (118) in a dispersed phase via a syringe pump (120) fluidically connected to the first dispenser, such that the primary droplet dispenses off from the first nozzle along the y-axis in the submerged fluid environment; storing a second fluid (124) in a pressurised fluid source (122); increasing a pressure of the second fluid in the pressurised fluid source, via a pressuring device (126) operatively connected to the pressurised fluid source; arranging a second dispenser (130) fluidically connected to the pressurised fluid source, on the base at a predefined distance from the first dispenser along the x-axis; adapting a second nozzle (132) in the second dispenser, oriented at a predefined angle (134) relative to the first nozzle in a cross-flow configuration, for dispensing a micro-jet (136) of the high pressure second fluid towards the primary droplet of the first fluid, wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween; controlling, using a regulating valve (138) arranged between the pressurised fluid source and the second dispenser, a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser; and operating the regulating valve, via a processor (140) operatively connected to the regulating valve, for dispensing the micro-jet of the high pressure second fluid upon a surface region (142) of the primary droplet, when a radius (116R) of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet for pinching off the primary droplet from the first dispenser.

14. The method as claimed in claim 13, further comprising controlling at least one parameter associated with an interaction between the micro-jet (136) of the high pressure second fluid (124) and the primary droplet (116) to maintain Weber number for switching between modes of pinching off the primary droplet, wherein the modes of pinching off comprises: a first mode for pinching off the primary droplet into a single-droplet formation, when the weber number is less than 11; a second mode for pinching off the primary droplet into a multi-droplet formation, when the weber number is between 11 and 350; and a third mode for pinching off the primary droplet into a spray formation, when the weber number is more than 350.

Description:TECHNICAL FIELD
[0001] The present disclosure relates to shear force-based droplet generation, in particular, the present disclosure relates to a droplet generation device and a method for a shear force-based droplet generation in a submerged fluid environment.
BACKGROUND
[0002] Fluidic microjets are fundamental to various technological applications, including microfluidics, inkjet printing, biomedical delivery systems, microfabrication processes, and precision cleaning. In such applications, precise control over liquid deposition at micro-scale dimensions is essential. Such precise control is often achieved through droplet generators, which are devices configured to produce discrete liquid droplets with controlled size and frequency.
[0003] Conventional droplet generation techniques typically employ microfluidic devices based on flow within confined channels. Such microfluidic devices produce uniform droplets at high frequencies, but often require additional arrangements to generate isolated droplets on demand.
[0004] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.
SUMMARY
[0005] The present disclosure provides a shear force-based droplet generation device and a method for a shear force-based droplet generation operable in a submerged fluid environment. The present disclosure addresses the technical problem of how to achieve controlled and repeatable formation and detachment of the primary droplet while maintaining flexibility in size of the primary droplet, breakup mode, and operating conditions. The present disclosure aims to provide a solution that overcomes at least partially the problems encountered in the prior art and provides an improved shear force-based droplet generation device and an improved method for a shear force-based droplet generation in a submerged fluid environment enabling controlled and repeatable formation and detachment of a primary droplet.
[0006] One or more objectives of the present disclosure are achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
[0007] In one aspect, the present disclosure provides a shear force-based droplet generation device operable in a submerged fluid environment. The shear force-based droplet generation device comprises a base extending along an x-axis, a y-axis, and a z-axis. Moreover, the shear force-based droplet generation device comprises a first dispenser arranged on the base, the first dispenser comprising a first nozzle oriented along the y-axis and adapted to dispense a primary droplet of a first fluid in a dispersed phase via a syringe pump fluidically connected to the first dispenser, wherein the primary droplet dispenses off from the first nozzle along the y-axis in the submerged environment. Furthermore, the shear force-based droplet generation device comprises a pressurised fluid source configured to store a second fluid. Furthermore, the shear force-based droplet generation device comprises a pressuring device operatively connected to the pressurised fluid source to increase a pressure of the second fluid. Furthermore, the shear force-based droplet generation device comprises a second dispenser fluidically connected to the pressurised fluid source and arranged on the base at a predefined distance from the first dispenser along the x-axis, the second dispenser comprising a second nozzle oriented at a predefined angle relative to the first nozzle in a cross-flow configuration, wherein the second nozzle is adapted to dispense a micro-jet of the high pressure second fluid towards the primary droplet of the first fluid, and wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween. Furthermore, the shear force-based droplet generation device comprises a regulating valve arranged between the second dispenser and the pressurised fluid source, the regulating valve adapted to control a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser. Furthermore, the shear force-based droplet generation device comprises a processor operatively connected to the pressuring device and the regulating valve, and configured to operate the regulating valve to dispense the micro-jet of the high pressure second fluid upon a surface region of the primary droplet, when a radius of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet to pinch off the primary droplet from the first dispenser
[0008] The shear force-based droplet generation device of the present disclosure enables controlled generation and separation of the primary droplet by actuating the micro-jet when the radius of the primary droplet reaches a predefined threshold, thereby differentiating droplet formation from separation of the primary droplet. The cross-flow configuration between the first nozzle and the second nozzle applies the localized shear force to the primary droplet, resulting in repeatable and controlled pinch-off of the primary droplet at the first nozzle. The operation of the regulating valve by the processor provides temporal control of the micro-jet, leading to generation of consistent sizes of the primary droplet and reduced dependence on variations in the supply rate of the primary droplet. The shear force-based droplet generation device of the present disclosure operates in the submerged environment, thereby eliminating the requirement for microchannels and reducing clogging and fabrication constraints. Further, the predefined distance and the predefined angle between the first nozzle and the second nozzle permit independent control of interaction location and shear intensity, enabling selective generation of either isolated droplets or clusters of droplets by adjusting parameters of the micro-jet. The controlled pinch-off of the primary droplet, thereby enables flexible operation and applicability of the shear force-based droplet generation device to a range of immiscible fluid pairs, while supporting scalability and integration of the shear force-based droplet generation device into laboratory and industrial applications.
[0009] In another aspect, the present disclosure provides a method for a shear force-based droplet generation in a submerged fluid environment. The method comprises arranging a first dispenser on a base extending along an x-axis, a y-axis, and a z-axis. Moreover, the method comprises adapting a first nozzle of the first dispenser arranged along the y-axis for dispensing a primary droplet of a first fluid in a dispersed phase via a syringe pump fluidically connected to the first dispenser, such that the primary droplet dispenses off from the first nozzle along the y-axis in the submerged fluid environment. Furthermore, the method comprises storing a second fluid in a pressurised fluid source. Furthermore, the method comprises increasing a pressure of the second fluid in the pressurised fluid source, via a pressuring device operatively connected to the pressurised fluid source. Furthermore, the method comprises arranging a second dispenser fluidically connected to the pressurised fluid source, on the base at a predefined distance from the first dispenser along the x-axis. Furthermore, the method comprises adapting a second nozzle in the second dispenser, oriented at a predefined angle relative to the first nozzle in a cross-flow configuration, for dispensing a micro-jet of the high pressure second fluid towards the primary droplet of the first fluid, wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween. Furthermore, the method comprises controlling, using a regulating valve arranged between the pressurised fluid source and the second dispenser, a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser. Furthermore, the method comprises operating the regulating valve, via a processor operatively connected to the regulating valve, for dispensing the micro-jet of the high pressure second fluid upon a surface region of the primary droplet, when a radius of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet for pinching off the primary droplet from the first dispenser.
[0010] The method for the shear force-based droplet generation in the submerged fluid environment achieves all the advantages and technical effects of the shear force-based droplet generation device for the shear force-based droplet generation in the submerged fluid environment in the present disclosure.
[0011] Additional aspects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
[0013] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG.1 illustrates a schematic representation of a shear force-based droplet generation device operable in a submerged fluid environment, in accordance with an embodiment of the present disclosure;
FIGs. 2A and 2B illustrate schematic representations of an enlarged view of the cross-flow configuration between the first nozzle and the second nozzle, in accordance with the embodiment of the present disclosure;
FIGs. 3A and 3B is a shear force-based droplet generation device, in accordance with the embodiment of the present disclosure.
FIG. 4 illustrates a schematic representation of a sequence of images of the micro-jet dispensed from the second nozzle, in accordance with the embodiment of the present disclosure;
FIG. 5 illustrates a schematic illustration of a sequence of images of the formation of the micro-jet dispensed from the second nozzle, in accordance with the embodiment of the present disclosure;
FIG. 6 illustrates a schematic representation of a sequence of images illustrating interaction between the micro-jet dispensed from the second nozzle and the primary droplet of different initial droplet diameter at a low Weber number, in accordance with the embodiment of the present disclosure;
FIG. 7 illustrates a schematic representation of a sequence of images illustrating breakup of primary droplets having different initial droplet diameters during interaction with the micro-jet dispensed from the second nozzle at a high Weber number, in accordance with an embodiment of the present disclosure; and
FIGs. 8A-8B illustrate a flowchart depicting various steps of a method for a shear force-based droplet generation in a submerged fluid environment, in accordance with an embodiment of the present disclosure.
[0014] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
[0015] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practicing the present disclosure are also possible.
[0016] FIG. 1 illustrates a schematic representation of a shear force-based droplet generation device operable in a submerged fluid environment, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a shear force-based droplet generation device 100 (referred to as a device 100 hereinafter), operable in a submerged fluid environment.
[0017] The device 100 comprises a base 110 extending along an x-axis, a y-axis, and a z-axis. Moreover, the device 100 comprises a first dispenser 112 arranged on the base 110, the first dispenser 112 comprising a first nozzle 114 oriented along the y-axis and adapted to dispense a primary droplet 116 of a first fluid 118 in a dispersed phase via a syringe pump 120 fluidically connected to the first dispenser 112, wherein the primary droplet 116 dispenses off from the first nozzle 114 along the y-axis in the submerged environment. Furthermore, the device 100 comprises a pressurised fluid source 122 configured to store a second fluid 124. Furthermore, the device 100 comprises a pressuring device 126 operatively connected to the pressurised fluid source 122 to increase a pressure of the second fluid 124. Furthermore, the device 100 comprises a second dispenser 130 fluidically connected to the pressurised fluid source 122 and arranged on the base 110 at a predefined distance 112D from the first dispenser 112 along the x-axis, the second dispenser 130 including a second nozzle 132 oriented at a predefined angle relative to the first nozzle 114 in a cross-flow configuration, wherein the second nozzle 132 is adapted to dispense a micro-jet 136 of the high pressure second fluid 124 towards the primary droplet 116 of the first fluid 118, and wherein the first fluid 118 and the second fluid 124 are immiscible and have an interfacial surface tension therebetween. Furthermore, the device 100 comprises a regulating valve 138 arranged between the second dispenser 130 and the pressurised fluid source 122, the regulating valve 138 adapted to control a flow of the micro-jet 136 of the high pressure second fluid 124 dispensed from the second dispenser 130. Furthermore, the device 100 comprises a processor 140 operatively connected to the pressuring device 126 and the regulating valve 138, and configured to operate the regulating valve 138 to dispense the micro-jet 136 of the high pressure second fluid 124 upon a surface region 142 of the primary droplet 116, when a radius of the primary droplet 116 is less than or equal to a predefined threshold, such that the micro-jet 136 of the high pressure second fluid 124 applies the shear force on the primary droplet 116 to pinch off the primary droplet 116 from the first dispenser 112.
[0018] The device 100 enables controlled separation of the primary droplet 116 by actuating the micro-jet 136 when the radius of the primary droplet 116 reaches a predefined threshold, thereby differentiating the droplet formation from the droplet separation. The crossflow configuration between the first nozzle 114 configured to form the primary droplet 116 and the second nozzle 132 configured to dispense the micro-jet 136 applies the localized shear force on the primary droplet 116, resulting in repeatable and controlled pinch-off the primary droplet 116 at the first nozzle 114. The operation of the regulating valve 138 by the processor 140 provides temporal control of the micro-jet 136, leading to consistent droplet sizes of the primary droplet 116 and reduced dependence on variations in the supply rate of the primary droplet 116. The device 100 operates in the submerged environment, thereby eliminating the requirement for microchannels and reducing clogging and fabrication constraints. Further, the predefined distance 112D and the predefined angle between the first nozzle 114 and the second nozzle 132 permit independent control of the interaction location and shear intensity, enabling selective generation of either isolated droplets or a cluster of droplets by adjusting parameters of the micro-jet 136. The separation of the droplet growth and the droplet pinch off mechanisms provides flexibility in operation, enhances applicability of the device 100 to a range of immiscible fluid pairs, and provides efficient use of pressurised fluid, while the modular configuration of the device 100 facilitates scalability and integration of the device 100 into laboratory and industrial applications.
[0019] Throughout the present disclosure, the term "submerged environment" refers to an unconfined liquid-filled ambient medium forming a continuous phase, within which the first nozzle 114 and the second nozzle 132 are immersed, and in which the primary droplet 116 is formed at the first nozzle 114 and detached by interaction with the micro-jet 136 while remaining fully surrounded by the continuous liquid phase. By way of example and without limitation, the submerged environment may encompass confined or enclosed environments, biological or physiological environments, industrial processing environments, and laboratory or diagnostic settings.
[0020] Throughout the present disclosure, the term "base" refers to a structural support element of the device 100 providing a common mounting platform for other components of the device 100. The base 110 extends along the x-axis, the y-axis, and the z-axis, thereby defining a three-dimensional coordinate system used to describe the spatial arrangement and orientation of the first dispenser 112 and the second dispenser 130 relative to one another. The base 110 provides positional stability and alignment for the first dispenser 112 and the second dispenser 130 to enable consistent spatial relationships during operation of the device 100 in the submerged environment.
[0021] The extension of the base 110 along the x-axis, the y-axis, and the z-axis defines orthogonal reference directions for positioning and orienting components mounted on the base 110. The x-axis is used to define a lateral separation between the first dispenser 112 and the second dispenser 130, the y-axis corresponds to a direction along which the primary droplet 116 is dispensed from the first nozzle 114, and the z-axis provides a vertical reference perpendicular to the x-axis and the y-axis. The x-axis, the y-axis, and the z-axis helps in enabling precise and repeatable placement of the first dispenser 112 and the second dispenser 130 on the base 110.
[0022] In an implementation, the base 110 includes holes configured to receive suction cups therein. The suction cups help in securing the base 110 firmly to a rigid structure during interaction of the high-pressure micro-jet 136 with the primary droplet 116.
[0023] Throughout the present disclosure, the term "first dispenser" refers to a fluid dispensing unit configured to supply the first fluid 118 for droplet formation. The first dispenser 112 is arranged on the base 110, such that the first dispenser 112 occupies a fixed and predefined position relative to other components mounted on the base 110. The arrangement of the first dispenser 112 on the base 110 establishes a stable spatial reference for dispensing the primary droplet 116 and for interaction of the primary droplet 116 with the micro-jet 136 dispensed from the second dispenser 130. The first dispenser 112 being arranged on the base 110 means that the first dispenser 112 is mechanically supported and positioned on the base 110. The base 110 maintains the position and orientation of the first dispenser 112 relative to the x-axis, the y-axis, and the z-axis. Such arrangement enables dispensing of the primary droplet 116 from the first dispenser 112 to occur at a known and repeatable location in the submerged environment.
[0024] Throughout the present disclosure, the term "first nozzle" refers to an outlet portion of the first dispenser 112 through which the first fluid 118 is dispensed. The first nozzle 114 is oriented along the y-axis defined by the base 110. The orientation of the first nozzle 114 along the y-axis determines the direction in which the primary droplet 116 is dispensed from the first dispenser 112 into the submerged environment, and subsequently, enables the primary droplet 116 to be dispensed off from the first nozzle 114 along the y-axis. Throughout the present disclosure, the term "primary droplet" refers to a discrete volume of the first fluid 118 formed at the first nozzle 114 during dispensing of the first fluid 118 from the first dispenser 112. The primary droplet 116 grows at or near an outlet of the first nozzle 114 prior to be pinched off from the first nozzle 114. The primary droplet 116 is dispensed from the first nozzle 114 for subsequent interaction with the micro-jet 136 dispensed from the second nozzle 132.
[0025] Throughout the present disclosure, the term "first fluid" refers to a fluid supplied to the first dispenser 112 for formation of the primary droplet 116. The first fluid 118 is dispensed from the first nozzle 114 in the form of the primary droplet 116. The first fluid 118 constitutes the dispersed phase within a surrounding continuous liquid phase present in the submerged environment. Throughout the present disclosure, the term "dispersed phase" refers to a phase of the first fluid 118 existing as discrete droplets within the submerged environment. The first fluid 118 forms the dispersed phase when the primary droplet 116 is dispensed from the first nozzle 114 and is surrounded by the continuous liquid phase of the submerged environment.
[0026] Throughout the present disclosure, the term "syringe pump" refers to a fluid delivery device fluidically connected to the first dispenser 112. The syringe pump 120 is adapted to supply the first fluid 118 to the first dispenser 112 at a controlled flow rate. The fluidic connection between the syringe pump 120 and the first dispenser 112 enables gradual and controlled formation of the primary droplet 116 at the first nozzle 114. The syringe pump 120 provides controlled volumetric displacement of the first fluid 118 toward the first nozzle 114, enabling precise regulation of a size of the primary droplet 116 and dispensing timing.
[0027] The first nozzle 114 being arranged along the y-axis and dispensing the primary droplet 116 along the y-axis in the submerged environment improves control over formation, release, and trajectory of the primary droplet 116. The submerged environment reduces the influence of gravitational effects, while the syringe pump 120 enables accurate and repeatable delivery of the first fluid 118 for the formation of the primary droplet 116. As a result, the arrangement achieves improved precision and repeatability in generation of the primary droplet 116, reduced size variability of the primary droplet 116, and improved stability of the dispersed phase immediately after dispensing. The axial orientation of the first nozzle 114 facilitates consistent release direction of the primary droplet 116, while operation in the submerged environment minimizes splashing, evaporation, and uncontrolled breakup of the primary droplet 116.
[0028] Throughout the present disclosure, the term "pressurised fluid source" refers to a fluid containment component adapted to store the second fluid 124 prior to dispensing. The pressurised fluid source 122 is adapted to hold the second fluid 124 under conditions suitable for subsequent pressurisation and delivery to the second dispenser 130. The pressurised fluid source 122 functions as a supply reservoir for the second fluid 124 that is dispensed as the micro-jet 136 for interaction with the primary droplet 116 formed by the first dispenser 112.
[0029] Throughout the present disclosure, the term "second fluid" refers to a fluid configured to be dispensed as a high-velocity micro-jet from the second dispenser 130 toward the primary droplet 116. The second fluid 124 is immiscible with the first fluid 118 and exhibits the interfacial surface tension therewith. The second fluid 124 is pressurised by the pressuring device 126 and the flow is regulated to generate a controlled shear force upon interaction with the primary droplet 116. The second fluid 124 is selected and operated such that the applied shear force facilitates controlled deformation and pinch off of the primary droplet 116, thereby enabling repeatable droplet pinch-off under a range of operating conditions.
[0030] Throughout the present disclosure, the term "pressuring device" refers to a component configured to increase and regulate the pressure of the second fluid 124 supplied to the second dispenser 130 for generation of the micro-jet 136. The pressuring device 126 operates by applying mechanical, pneumatic, or hydraulic force to the second fluid 124 to achieve a desired pressure or flow condition. The pressuring device 126 being configured to increase the pressure of the second fluid 124 enables controlled delivery of the second fluid 124 with sufficient momentum to the second nozzle 132 in a predictable manner. As a result, the pressuring device 126 enables stable and repeatable formation of the micro-jet 136, precise control of shear forces applied to the primary droplet 116, and reliable modulation of droplet pinch off behaviour across different operating parameters. In an embodiment, the pressuring device 126 is a compressor.
[0031] Throughout the present disclosure, the term "second dispenser" refers to a fluid dispensing unit adapted to enable the dispensing of the high pressure second fluid 124, via the second nozzle 132. The second dispenser 130 is fluidically connected to the pressurised fluid source 122 and is arranged on the base 110 such that the second dispenser 130 occupies a fixed position relative to the first dispenser 112. Throughout the present disclosure, the term "predefined distance" refers to a fixed spatial separation between the first dispenser 112 and the second dispenser 130 measured along the x-axis. The predefined distance 112D establishes a controlled interaction region in which the micro-jet 136 dispensed from the second dispenser 130 via the second nozzle 132, impinges upon the surface region 142 of the primary droplet 116. The predefined distance 112D is selected based on the location and effectiveness of shear interaction required between the micro-jet 136 of the high pressure second fluid 124 and the primary droplet 116 of the first fluid 118.
[0032] Throughout the present disclosure, the term "second nozzle" refers to an outlet portion of the second dispenser 130 through which the second fluid 124 is discharged. The second nozzle 132 is oriented at the predefined angle relative to the first nozzle 114. The orientation of the second nozzle 132 determines the direction of the micro-jet 136 dispensed from the second dispenser 130 toward the primary droplet 116. Throughout the present disclosure, the term "predefined angle" refers to an angular orientation of the second nozzle 132 relative to the first nozzle 114. The predefined angle 134 establishes a directional relationship between the second nozzle 132 and the first nozzle 114 such that the micro-jet 136 discharged from the second nozzle 132 intersects the primary droplet 116 formed at the first nozzle 114 to enable the pinch off of the primary droplet 116 from the first nozzle 114.
[0033] In an embodiment, the predefined angle is between a range of 11 to 100 degrees. The predefined angle is selected to be in the range of 11 to 100 degrees as the range of 11 to 100 degrees enable to establish the cross-flow configuration between the first nozzle 114 and the second nozzle 132. The predefined angle is selected to be the aforementioned angular range to promote impingement of the micro-jet 136 discharged from the second nozzle 132 on the surface region 142 with sufficient transverse momentum to generate shear force rather than axial displacement. As a result, the predefined angle being in the aforementioned angular range improves reliability of pinching off the primary droplet 116, reduces unintended displacement of the primary droplet 116, and improves consistency of pinching off of the primary droplet 116 across different operating conditions.
[0034] Throughout the present disclosure, the term "cross-flow configuration" refers to an arrangement in which the second nozzle 132 is oriented at the predefined angle relative to the first nozzle 114 such that the micro-jet 136 dispensed from the second nozzle 132 flows across a direction in which the primary droplet 116 is dispensed from the first nozzle 114. The cross-flow configuration enables application of the shear force to the primary droplet 116 by the micro-jet 136. Throughout the present disclosure, the term "micro-jet" refers to a high-velocity, narrow stream of the second fluid 124 dispensed from the second nozzle 132 under high pressure. The micro-jet 136 is directed toward the surface region 142 of the primary droplet 116 to apply the shear force sufficient to cause the pinch off of the primary droplet 116 from the first dispenser 112.
[0035] Throughout the present disclosure, the term "interfacial surface tension" refers to a surface tension existing at an interface between the first fluid 118 and the second fluid 124 due to immiscibility of the first fluid 118 and the second fluid 124. The interfacial surface tension resists deformation of the primary droplet 116 and cooperates with shear forces applied by the micro-jet 136 to govern pinch-off behaviour of the primary droplet 116. The fluidic connection between the second dispenser 130 and the pressurised fluid source 122 enables delivery of the high-pressure second fluid 124 to the second nozzle 132. The immiscibility between the first fluid 118 and the second fluid 124, together with the presence of the interfacial surface tension, promotes controlled shear-induced interaction between the micro-jet 136 and the primary droplet 116.
[0036] Throughout the present disclosure, the term "regulating valve" refers to a flow control component arranged between the pressurised fluid source 122 and the second dispenser 130. The regulating valve 138 is adapted to control the flow of the micro-jet 136 of the high pressure second fluid 124 dispensed from the second dispenser 130. The regulating valve 138 selectively controls dispensing of the micro-jet 136. The regulating valve 138 enables the micro-jet 136 to be dispensed only when interaction with the primary droplet 116 is required, thereby avoiding continuous or premature shear. The regulating valve 138 operates by regulating at least one of flow rate, duration, or timing of the second fluid 124 supplied to the second dispenser 130, resulting in controlled generation of the micro-jet 136. The controlled operation of the regulating valve 138 produces the localized shear force on the primary droplet 116 sufficient to cause pinch-off from the first dispenser 112, while reducing unintended droplet fragmentation and improving repeatability and reliability of droplet generation.
[0037] Throughout the present disclosure, the term "processor" refers to a computational element or a combination or computational elements working together operable to execute various steps performed by the device 100. Examples of the processor 140 include, but are not limited to, a microprocessor, a microcontroller, a complex instruction set computing (CISC) microprocessor, a reduced instruction set (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or any other type of processing circuit. Furthermore, the processor 140 may refer to one or more individual processors, processing devices and various elements associated with a processing device that may be shared by other processing devices. In other words, the processor 140 may be capable of working as a standalone unit or a part of a combination of standalone units. Additionally, one or more individual processors, processing devices and elements are arranged in various architectures for responding to and processing the instructions that execute the steps of the device 100. Herein, communications between the processor 140 and the pressurising device 126, and between the processor 140 and the regulating valve 138, are depicted by dashed lines. The processor 140 is configured to control actuation of the regulating valve 138 based on a condition associated with the primary droplet 116. In some embodiments, the processor 140 is operatively coupled to a memory and one or more storage components, thereby forming a computational system configured to execute software instructions.
[0038] Throughout the present disclosure, the term "surface region" refers to a localized portion of an outer surface of the primary droplet 116 upon which the micro-jet 136 of the high pressure second fluid 124 is directed to apply the shear force. Throughout the present disclosure, the term "radius" refers to a radial dimension representative of the size of the primary droplet 116, irrespective of shape of the primary droplet 116. Throughout the present disclosure, the term "predefined threshold" refers to a predetermined value of the radius of the primary droplet 116 used as a control criterion by the processor 140 for initiating operation of the regulating valve 138. Throughout the present disclosure, the term "pinch-off" refers to detachment of the primary droplet 116 from the first nozzle 114 as a result of shear forces applied by the micro-jet 136 overcoming interfacial and retaining forces acting on the primary droplet 116.
[0039] The processor 140 operates the regulating valve 138 such that the micro-jet 136 of the high-pressure second fluid 124 is dispensed onto the surface region 142 of the primary droplet 116 when the radius of the primary droplet 116 is less than or equal to the predefined threshold. The processor 140 is configured to coordinate application of shear with growth of the primary droplet 116, thereby preventing premature or uncontrolled detachment of the primary droplet 116. The processor 140 operates by monitoring or receiving information indicative of the radius and actuating the regulating valve 138 when the radius of the primary droplet 116 is less than or equal to the predefined threshold, causing the micro-jet 136 to impinge upon the surface region 142. The controlled operation of the processor 140 in relation to the surface region 142, the predefined threshold, and the radius of the primary droplet 116 improves repeatability of generation of the primary droplet 116, enables precise size control of the primary droplet 116, and reduces unintended fragmentation of the primary droplet 116.
[0040] In some embodiments, a diameter of the primary droplet 116 pinched off from the first dispenser 112 is in a range of 500 micrometres (μm) to 5 millimetres. In this regard, the diameter being in the specified range allows the device 100 to accommodate applications requiring formation of relatively large, discrete droplets while maintaining precise control over droplet size. The diameter being in the specified range balances stability during droplet growth with controllability during pinch-off, thereby making the device 100 suitable for a variety of fluidic, diagnostic, and processing applications. As a result, the device 100 enables repeatable generation of the primary droplet 116 with consistent size characteristics, reduced variability in droplet volume, and improved control over droplet formation. The ability to reliably generate the primary droplet 116 within the specified diameter range enhances device 100 robustness and expands applicability of the device 100 across laboratory and industrial droplet-based systems.
[0041] In some embodiments, the processor 140 is configured to control at least one operating parameter associated with the interaction between the micro-jet 136 of the high pressure second fluid 124 and the primary droplet 116 to maintain a Weber number for switching between modes of pinching off the primary droplet 116, wherein the modes of pinching off comprises:
a first mode to pinch off the primary droplet 116 into a single-droplet formation, when the weber number is less than 11;
a second mode to pinch off the primary droplet 116 into a multi-droplet formation, when the weber number is between 11 and 350; and
a third mode to pinch off the primary droplet 116 into a spray formation, when the weber number is more than 350.
[0042] The one or more operating parameters of the micro-jet 136 that are modulated by the processor 140, includes but are not limited to a velocity, a diameter, a density, and properties of a continuous phase associated with the micro-jet 136, thereby controlling inertial forces of the micro-jet 136 relative to the interfacial surface tension of the primary droplet 116. By adjusting the one or more operating parameters, the processor 140 maintains the Weber number within predefined ranges corresponding to different pinching-off modes. Notably, controlling the Weber number provides a dimensionless framework for governing the mode of pinching off the primary droplet 116 based on a balance between inertial forces and surface tension forces. The maintain of the weber number enables predictable and repeatable switching between the modes of pinching off the primary droplet 116 without requiring changes to nozzle geometry or fluid composition, thereby simplifying device 100 design while expanding functional versatility of the device 100.
[0043] The mode of pinching off being the first mode enables generation of the single droplet with a predictable size and shape, which is advantageous in applications requiring precise volumetric control and minimal droplet dispersion of the primary droplet 116 being pinched off. The Weber number being maintained to be less than 11 results in surface tension dominating the interaction, thereby preventing excessive deformation or fragmentation of the primary droplet 116. Under such condition, application of the localized shear induces a controlled necking at the interface between the primary droplet 116 and the first dispenser 112, causing clean pinch off of the primary droplet 116 as the single, coherent droplet without further breakup. The first mode provides high repeatability in the pinch off, narrow droplet size distribution, and improved control over droplet volume of the primary droplet 116. The first mode reduces unintended droplet breakup and enhances stability of droplet formation, thereby supporting accurate and reliable droplet generation for precision fluidic applications.
[0044] The mode of pinching off being the second mode enables pinching-off of the primary droplet 116 into the multi-droplet formation when the Weber number is maintained between 11 and 350. The Weber number being maintained to be between 11 and 350, causes the inertial forces imparted by the micro-jet 136 to be comparable to or exceed interfacial surface tension forces, resulting in increased deformation of the primary droplet 116 upon interaction with the micro-jet 136. Under such conditions, application of the localized shear induces controlled elongation and breakup of the primary droplet 116, leading to division of the primary droplet 116 into a plurality of secondary droplets in a predictable manner. The second mode enables controlled generation of multiple droplets with defined size distributions, while maintaining repeatability of droplet formation. By maintaining the Weber number in the range of 11 to 350, the device 100 achieves a balance between stability and breakup of the primary droplet 116, thereby reducing uncontrolled fragmentation and enabling selective production of droplet clusters. The second mode supports applications requiring increased droplet throughput or spatial droplet distributions and improves control over droplet formation dynamics in droplet-based fluidic systems.
[0045] The mode of pinching off being the third mode enables pinching-off of the primary droplet 116 into the spray formation when the Weber number is greater than 350. In this regard, inertial forces imparted by the micro-jet 136 substantially exceed the interfacial surface tension forces of the primary droplet 116, resulting in deformation and destabilization of the primary droplet 116 upon interaction with the micro-jet 136. Under such conditions, application of the localized shear produces rapid atomization of the primary droplet 116, causing disintegration of the primary droplet 116 into a fine spray of a plurality of small droplets. The third mode facilitates generation of the fine spray with high droplet dispersion and reduced characteristic droplet size. The third mode supports applications requiring widespread droplet distribution, or rapid mass transfer. By controlling the Weber number to be more than 350, the device 100 enables repeatable and controlled spray formation while maintaining programmable control over droplet breakup behaviour through processor-controlled operating parameters.
[0046] As a result, the different modes of pinching off the primary droplet 116 enables selective generation of single-droplet formation, multi-droplet formation, or spray formation, thereby improving adaptability of the device 100 across a wide range of applications. Further, controlling the droplet formation based on the Weber number helps in improving reproducibility of droplet size distributions and enables programmable generation of droplets through processor-controlled operating parameters.
[0047] In some embodiments, the pressurised fluid source 122 comprises a storage tank externally pressurized using a compressed fluid, and wherein the regulating valve 138 comprises a solenoid valve, such that a pressure within the storage tank and an opening duration of the solenoid valve are controllable to modulate a strength of the micro-jet 136.
[0048] In this regard, the external pressurisation of the storage tank establishes a controllable internal pressure acting on the second fluid 124 stored therein. The external pressurisation of the storage tank provides a stable pressure source, while solenoid valve actuation enables rapid, repeatable, and precisely timed release of the second fluid 124 toward the primary droplet 116. The solenoid valve is operable between an open state and a closed state to selectively permit fluid flow from the storage tank to the second dispenser 130. By adjusting the pressure within the storage tank and controlling the opening duration of the solenoid valve, at least one of a flow rate, velocity, momentum, and duration of the micro-jet 136 dispensed from the second nozzle 132 is modulated. The controlled modulation of the strength of the micro-jet 136 is required to apply the intended shear force to the primary droplet 116 in the submerged fluid environment. The ability to independently adjust tank pressure and valve opening duration allows selective generation of different droplet formation, including single-droplet formation, multi-droplet breakup, and spray formation. Further, the decoupling of droplet generation from gravity-driven mechanisms improves compatibility with complex and non-Newtonian fluids, while maintaining consistent micro-jet performance across operating conditions.
[0049] In some embodiments, the first fluid 118 is a non-Newtonian or a complex fluid. In this regard, when a non-Newtonian or complex fluid is used as the first fluid 118 in the submerged fluid environment, the droplet formation and pinch-off behaviour of the primary droplet 116 is influenced by the first fluid’s rheological properties rather than solely by surface tension and gravity. The first fluid 118 being the non-Newtonian or the complex fluid significantly broadens the applicability of the device 100. As a result, the device 100 allows reliable generation of droplets from the non-Newtonian and the complex fluid, controlled switching between droplet formation regimes even for rheologically complex materials. Further, the device 100 is advantageous for applications involving biological samples, soft materials, or advanced formulations, where precise droplet control is required despite non-ideal fluid behaviour.
[0050] In some embodiments, the processor 140 is operatively connected to the pressurised fluid source 122 and the regulating valve 138 to control pressurisation of the second fluid 124 and actuation of the regulating valve 138 for modulating the strength of the micro-jet 136.
[0051] In this regard, the processor 140 being operatively coupled with the pressurised fluid source 122 enables the processor 140 to adjust a pressure level of the second fluid 124 by controlling the pressurising device 126 associated with the pressurised fluid source 122. The processor 140 further controls actuation of the regulating valve 138 by selectively opening and closing the regulating valve 138 for defined durations. By controlling the pressure of the second fluid 124 and the actuation of the regulating valve 138, the processor 140 modulates at least one characteristic of the micro-jet 136, including flow rate, velocity, momentum, and duration. The coordinated control of the pressurisation of the second fluid 124 and the actuation of the regulating valve 138 enables application of the appropriate shear force to the primary droplet 116 during interaction with the micro-jet 136, particularly in applications requiring repeatable droplet pinch-off or controlled transition between different modes of pinching off the primary droplet 116. The processor-based control of both the pressurisation of the second fluid 124 and the actuation of the regulating valve 138 provides improved precision, repeatability, and responsiveness in generation of the micro-jet 136 and provides dynamic adjustment of the strength of the micro-jet 136 in response to droplet size or operating conditions, facilitates consistent droplet pinch-off behaviour, and supports selective generation of single-droplet, multi-droplet, or spray formations.
[0052] In some embodiments, the pressurised fluid source 122 comprises a pump disposed downstream of the pressurised fluid source 122, and wherein the regulating valve 138 includes a flow control valve disposed downstream of the pump, such that operation of the pump according to predefined timings and adjustment of the flow control valve to control a flow rate of the fluid and thereby modulate a strength of the micro-jet 136.
[0053] In this regard, the pump and the flow control valve together define a fluid delivery arrangement for generating and regulating the strength of the micro-jet 136. The pump is operable to drive the second fluid 124 from the fluid reservoir toward the second dispenser 130 according to predefined operating timings, speeds, or duty cycles. The flow control valve is adjustable to regulate a flow rate of the second fluid 124 delivered downstream of the pump. By coordinating operation of the pump and adjustment of the flow control valve, the flow rate, velocity, and duration of the micro-jet 136 dispensed from the second nozzle 132 are controlled, thereby modulating the strength of the micro-jet 136.
[0054] The pump being disposed downstream of the pressurised fluid source 122 provides a controllable and repeatable mechanism for delivering the second fluid 124 without reliance on the externally pressurised storage tank. The presence of the pump enables coarse control over fluid delivery of the second fluid 124, while downstream flow control provides fine adjustment of flow characteristics. Such configuration enables stable and adjustable generation of the micro-jet 136 with controllable strength and temporal characteristics. The independent control of pump operation and flow control valve adjustment improves repeatability of shear-induced droplet pinch-off and facilitates dynamic switching between different modes of pinching off the primary droplet 116.
[0055] In some embodiments, the pressurised fluid source 122 includes a piston-cylinder arrangement configured as a positive displacement pump, the piston being operable using a motorised arrangement or manually, such that a flow rate of the second fluid 124 and thereby a strength of the micro-jet 136 are adjustable by varying a piston velocity and a stroke length.
[0056] In this regard, the movement of the piston within the cylinder displaces a defined volume of the second fluid 124 toward the second dispenser 130. Subsequently, the flow rate of the second fluid 124 is controlled by adjusting at least one of: the piston velocity and the stroke length of the piston. By varying such parameters, the amount of second fluid 124 delivered per unit time and the duration of fluid delivery of the second fluid 124 are controlled, thereby regulating the velocity, momentum, and duration of the micro-jet 136 dispensed from the second nozzle 132. The piston-based positive displacement arrangement provides direct and predictable control over fluid delivery independent of downstream pressure variations. The piston-based positive displacement arrangement is advantageous for applications requiring precise volumetric dosing or where the second fluid 124 exhibits varying viscosity or compressibility. Such configuration enables highly accurate and repeatable control of the strength of the micro-jet 136 through direct adjustment of the piston motion parameters. The independent control of the piston velocity and the stroke length facilitate fine tuning of shear forces applied to the primary droplet 116, thereby improving consistency of droplet pinch-off and supporting selective generation of different droplet formation regimes.
[0057] FIGs. 2A and 2B illustrate schematic representations of an enlarged view of the cross-flow configuration between the first nozzle and the second nozzle, in accordance with the embodiment of the present disclosure. With reference to FIGs. 2A and 2B, there is shown the second nozzle 132 oriented at a predefined angle 134 relative to the first nozzle 114 in the cross-flow configuration. Moreover, the micro-jet 136 of the high pressure second fluid 124 is dispensed upon the surface region 142 of the primary droplet 116, when a radius 116R of the primary droplet 116 is less than or equal to the predefined threshold.
[0058] FIGs. 3A and 3B illustrate schematic representations of perspective views of a shear force-based droplet generation device, in accordance with the embodiment of the present disclosure. With reference to FIGs. 3A and 3B, there is shown the device 100. In an embodiment, the device 100 comprises a first holder 302 having a first axis 304 and configured to receive the first dispenser 112 therein, a second holder 306 having a second axis 308 and configured to receive the second dispenser 130 therein, wherein the first holder 302 and the second holder 306 are arranged on the base 110, and a relative positioning of the first dispenser 112 and the second dispenser 130 is adjustable along at least one of the x-axis and the y-axis on the base 110.
[0059] In this regard, the term "first holder" refers to a mounting structure configured to support and align the first dispenser 112. In this regard, the term "second holder" refers to a mounting structure configured to support and align the second dispenser 130. The first holder 302 and the second holder 306 are mounted on the base 110 in a manner that allows positional adjustment relative to one another along defined reference directions of the base 110 to enable controlled variation of spatial separation and alignment between formation of the primary droplet 116 and impingement locations of the micro-jet 136. The adjustment of the first holder 302 and the second holder 306 permits controlled modification of an interaction point between the primary droplet 116 during formation and impinging of the micro-jet 136 by varying at least one of lateral spacing and vertical alignment on the base 110. Such controlled repositioning modifies shear interaction conditions of the first fluid 118 and the second fluid 124, thereby enabling flexible control over the pinch off behaviour of the primary droplet 116. The adjustable mounting provided by the first holder 302 and the second holder 306 improves repeatability of droplet pinch-off, allows adaptation to different droplet sizes and operating conditions, and improves experimental and operational versatility of the device 100.
[0060] In some embodiments, the adjustable relative positioning comprises adjustment of at least one of: a first offset 310 between the first axis 304 and the second axis 308 along the x-axis and a second offset 312 between the first axis 304 and the second axis 308 along the y-axis, wherein adjustment of the first offset 310 shifts a location at which the micro-jet 136 interacts with the primary droplet 116 along the y-axis, and wherein adjustment of the second offset 312 shifts the location of interaction along the x-axis.
[0061] In this regard, the adjustable relative positioning enables controlled variation of spatial alignment between the x-axis associated with formation of the primary droplet 116 and the y-axis associated with delivery of the micro-jet 136. The variation of alignment in one direction alters the longitudinal position at which the micro-jet 136 encounters the primary droplet 116 during formation, while variation in both the directions alters the lateral point of impingement on the surface region 142. Such two-directional adjustment is provided to independently control the location and nature of interaction of the micro-jet 136 and the primary droplet 116 without changing geometry or operating conditions of the first nozzle 114 and the second nozzle 132. By modifying the interaction location in such manner, the shear distribution applied to the primary droplet 116 can be selectively altered, thereby enabling control over the pinch off of the primary droplet 116. Such adjustment improves operational flexibility, allows precise control over pinch-off dynamics, and improves repeatability of the pinch off across different sizes of the primary droplet 116.
[0062] In some embodiments, an orientation of the first dispenser 112 is adjustable to control a direction of movement of the primary droplet 116 along the y-axis. In this regard, the orientation of the first dispenser 112 is adjusted relative to the base 110, thereby changing the dispensing direction of the first fluid 118 and the trajectory of the primary droplet 116. Such adjustment allows the primary droplet 116 to move along the y-axis under the combined influence of gravity, fluid inertia, and interaction with the surrounding fluid in the submerged environment. Notably, providing adjustable orientation of the first dispenser 112 enables control over trajectory of the primary droplet 116 and positioning prior to interaction with the micro-jet 136 and moreover, allows alignment of the primary droplet 116 with respect to the second dispenser 130 and facilitates consistent interaction conditions with the micro-jet 136 across different operating configurations. As a result, adjustable orientation of the first dispenser 112 improves repeatability of positioning of the primary droplet 116 and reduces variability in the pinch-off behaviour of the primary droplet 116. Such flexibility supports adaptation to different sizes of the primary droplet 116, flow conditions, and application requirements, thereby improving robustness and versatility of the device 100.
[0063] FIG. 4 illustrates a schematic representation of a sequence of images of the micro-jet dispensed from the second nozzle, in accordance with the embodiment of the present disclosure. With reference to FIG. 4, there is shown a sequence of images 400, the images being compared at a common reference time under different operating parameters corresponding to an increasing Weber number.
[0064] The sequence of images 400 shows formation and temporal evolution of the micro-jet 136 dispensed from the second nozzle 132 having an inner diameter of 1.54 millimetre (mm), corresponding to the second dispenser 130. The sequence of images 400 shows progression of the micro-jet 136 with time advancing from left to right, where a reference time point (t = 0) is defined at a common axial distance from the second nozzle 132 for all operating conditions to facilitate comparison.
[0065] Each row in the sequence of images 400 correspond to increasing Weber number conditions associated with interaction between the micro-jet 136 and a surrounding fluid. At lower Weber numbers, the micro-jet 136 remains relatively coherent and collimated, indicating dominance of the interfacial surface tension over inertial forces. As the Weber number increases, inertial forces increasingly exceed the surface tension forces, resulting in earlier onset of spreading of the micro-jet 136, interfacial disturbance, and breakup, as visually evident in the progression from top to bottom.
[0066] The divergence of the micro-jet 136 is further characterised by a cone angle (2α), defined as a maximum angular spread of the micro-jet 136 measured from the second nozzle 132. As shown, the cone angle (2α) varies from approximately 11° to 16.5° with increasing Weber number, indicating increased transverse momentum and lateral expansion of the micro-jet 136. Such variation in cone angle (2α) directly influences shear intensity and interaction behaviour when the micro-jet 136 impinges upon the primary droplet 116, relating to cross-flow interaction and Weber-number-based switching between droplet pinch-off modes.
[0067] Further, control of Weber number enables modulation of the strength of the micro-jet 136, spreading behaviour, and temporal characteristics, thereby supporting selective generation of different droplet formation regimes, including single-droplet formation, multi-droplet formation, and spray formation.
[0068] FIG. 5 illustrates a schematic illustration of a sequence of images of the formation of the micro-jet dispensed from the second nozzle, in accordance with the embodiment of the present disclosure. With reference to FIG. 5, there is shown a sequence of images 500 of the formation of the micro-jet 136 dispensed from the second nozzle 132 having an inner diameter of 0.25 mm, the images are compared at a common reference time under different operating conditions corresponding to increasing Weber number.
[0069] FIG. 5 shows variations in coherence of the micro-jet 136, spreading behaviour, and transition to turbulent flow as the Weber number increases, with the cone angle (2α), defined as the maximum angular spread of the jet measured from the nozzle outlet, varying from approximately 4.5° to 13°.
[0070] As shown in FIG. 5, at lower Weber number, the micro-jet 136 remains narrow and well-collimated, indicating dominance of surface tension forces over inertial forces. As the Weber number increases, the micro-jet 136 exhibits increased lateral spreading, earlier onset of interfacial instabilities, and progressive loss of coherence, reflecting a growing influence of inertial forces relative to surface tension. At very high Weber numbers, the micro-jet 136 transitions rapidly into a turbulent and highly dispersed flow regime, characterized by broad cone angles and enhanced mixing with the surrounding fluid. The left-to-right progression depicts temporal evolution following ejection, while the top-to-bottom comparison highlights the effect of increasing Weber number on morphology of the micro-jet 136. Such behaviour corroborates Weber-number-based control of the strength of the micro-jet 136 and interaction dynamics, enabling selective modulation of shear forces applied during droplet pinch-off and controlled switching between different droplet formation regimes.
[0071] FIG. 6 illustrates a schematic representation of a sequence of images illustrating interaction between the micro-jet dispensed from the second nozzle and the primary droplet of different initial droplet diameter at a low Weber number, in accordance with the embodiment of the present disclosure. With reference to FIG. 6, there is shown the sequence of images 600 illustrating the breakup and pinch off behaviour of the primary droplet 116 having four different initial droplet diameters (D(d) ≈ 1 mm, 2.3 mm, 2.7 mm, and 5.1 mm) when interacting with the micro-jet 136 under operating conditions corresponding to a relatively low Weber number. The sequence of images 600 capture the temporal evolution of the interaction between the micro-jet 136 and the primary droplet 116.
[0072] As shown, the primary droplet 116 positioned closer to the second nozzle 132 initially interact with a starting vortex formed at the onset of the micro-jet 136. Such vortex-induced interaction generates localized shear and momentum transfer sufficient to dislodge the primary droplet 116 from equilibrium position while maintaining a coherent droplet structure. Owing to low Weber number, surface tension effects dominate over inertial forces, resulting in controlled deformation of the primary droplet 116 and detachment with minimal formation of secondary droplets.
[0073] FIG. 6 demonstrates that, across a range of initial droplet diameters, the configuration enables predictable droplet pinch off and breakup behaviour governed by the balance between jet-induced inertial forces and interfacial surface tension. Such behaviour supports controlled single-droplet manipulation and highlights the effectiveness of operating in low Weber number for applications requiring minimal fragmentation and high repeatability of droplet handling.
[0074] FIG. 7 illustrates a schematic representation of a sequence of images illustrating breakup of the primary droplets having different initial droplet diameters during interaction with the micro-jet dispensed from the second nozzle at a high Weber number, in accordance with an embodiment of the present disclosure. With reference to FIG. 7, there is shown a sequence of images 700 illustrating interactions between the primary droplet 116 and the micro jet 136 corresponding to high Weber number conditions, in which inertial forces of the micro-jet 136 significantly exceed interfacial surface tension forces of the primary droplet 116. For the four different initial droplet diameters (Dₙ ≈ 1 mm, 2.3 mm, 2.7 mm, and 5.1 mm), the high Weber number results in strong deformation of the primary droplet 116 upon impact with the micro-jet 136, leading to unstable interfacial dynamics. As shown, the primary droplets 116 undergo violent breakup characterized by formation of bag-like structures, elongated ligaments, and subsequent disintegration into clusters of fine secondary droplets.
[0075] The observed transition from coherent droplet deformation to extensive fragmentation is indicative of operation in high Weber number exceeding the threshold for multi-droplet breakup, where surface tension is insufficient to maintain droplet integrity against the imposed inertial stresses. Increasing droplet diameter further amplifies the effective Weber number for a given micro-jet momentum, thereby intensifying breakup severity and promoting formation of a cluster of droplets and sprays.
[0076] FIGs. 8A and 8B illustrate a flowchart depicting various steps of a method for a shear force-based droplet generation in a submerged fluid environment, in accordance with an embodiment of the present disclosure. With reference to FIG. 5, there is shown the method comprising steps 802 to 816.
[0077] At step 802, a first dispenser is arranged on a base extending along an x-axis, a y-axis, and a z-axis.
[0078] At step 804, a first nozzle of the first dispenser arranged along the y-axis, is adapted for dispensing a primary droplet of a first fluid in a dispersed phase via a syringe pump fluidically connected to the first dispenser, such that the primary droplet dispenses off from the first nozzle along the y-axis in the submerged fluid environment.
[0079] At step 806, a second fluid is stored in a pressurised fluid source.
[0080] At step 808, a pressure of the second fluid is increased in the pressurised fluid source, via a pressuring device operatively connected to the pressurised fluid source.
[0081] At step 810, a second dispenser fluidically connected to the pressurised fluid source is arranged on the base at a predefined distance from the first dispenser along the x-axis.
[0082] At step 812, a second nozzle in the second dispenser, oriented at a predefined angle relative to the first nozzle in a cross-flow configuration, is adapted for dispensing a micro-jet of the high pressure second fluid towards the primary droplet of the first fluid, wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween.
[0083] At step 814, a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser is controlled using a regulating valve arranged between the pressurised fluid source and the second dispenser.
[0084] At step 816, the regulating valve is operated for dispensing the micro-jet of the high pressure second fluid upon a surface region of the primary droplet, via a processor operatively connected to the regulating valve, when a radius of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet for pinching off the primary droplet from the first dispenser.
[0085] In some embodiments, the method 800 further comprises controlling at least one parameter associated with an interaction between the micro-jet of the high pressure second fluid and the primary droplet to maintain Weber number for switching between modes of pinching off the primary droplet, wherein the modes of pinching off comprises: a first mode for pinching off the primary droplet into a single-droplet formation, when the weber number is less than 11; a second mode for pinching off the primary droplet into a multi-droplet formation, when the weber number is between 11 and 350; and a third mode for pinching off the primary droplet into a spray formation, when the weber number is more than 350.
[0086] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.
, Claims:CLAIMS
We claim:
1. A shear force-based droplet generation device (100) operable in a submerged fluid environment, comprising:
a base (110) extending along an x-axis, a y-axis, and a z-axis;
a first dispenser (112) arranged on the base, the first dispenser comprising a first nozzle (114) oriented along the y-axis and adapted to dispense a primary droplet (116) of a first fluid (118) in a dispersed phase via a syringe pump (120) fluidically connected to the first dispenser, wherein the primary droplet dispenses off from the first nozzle along the y-axis in the submerged environment;
a pressurised fluid source (122) configured to store a second fluid (124);
a pressuring device (126) operatively connected to the pressurised fluid source to increase the pressure of the second fluid;
a second dispenser (130) fluidically connected to the pressurised fluid source and arranged on the base at a predefined distance (112D) from the first dispenser along the x-axis, the second dispenser comprising a second nozzle (132) oriented at a predefined angle (134) relative to the first nozzle in a cross-flow configuration, wherein the second nozzle is adapted to dispense a micro-jet (136) of the high pressure second fluid towards the primary droplet of the first fluid, and wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween;
a regulating valve (138) arranged between the second dispenser and the pressurised fluid source, the regulating valve adapted to control a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser; and
a processor (140) operatively connected to the pressuring device and the regulating valve, and configured to operate the regulating valve to dispense the micro-jet of the high pressure second fluid upon a surface region (142) of the primary droplet, when a radius (116R) of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet to pinch off the primary droplet from the first dispenser.
2. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the processor (140) is configured to control at least one operating parameter associated with an interaction between the micro-jet (136) of the high pressure second fluid (124) and the primary droplet to maintain a Weber number for switching between modes of pinching off the primary droplet (116), wherein the modes of pinching off comprises:
a first mode to pinch off the primary droplet into a single-droplet formation, when the weber number is less than 11;
a second mode to pinch off the primary droplet into a multi-droplet formation, when the weber number is between 11 and 350; and
a third mode to pinch off the primary droplet into a spray formation, when the weber number is more than 350.
3. The shear force-based droplet generation device (100) as claimed in claim 1, further comprising a first holder (302) having a first axis (304) and configured to receive the first dispenser (112) therein, a second holder (306) having a second axis (308) and configured to receive the second dispenser (130) therein, wherein the first holder and the second holder are arranged on the base (110), and a relative positioning of the first dispenser and the second dispenser is adjustable along at least one of the x-axis and the y-axis on the base.
4. The shear force-based droplet generation device (100) as claimed in claim 3, wherein the adjustable relative positioning comprises adjustment of at least one of: a first offset (310) between the first axis (304) and the second axis (308) along the x-axis and a second offset (312) between the first axis (304) and the second axis (308) along the y-axis, wherein adjustment of the first offset (310) shifts a location at which the micro-jet (136) interacts with the primary droplet (116) along the y-axis, and wherein adjustment of the second offset shifts the location of interaction along the x-axis.
5. The shear force-based droplet generation device (100) as claimed in claim 1, wherein a diameter of the primary droplet (116) pinched off from the first dispenser (112) is in a range of 500 micrometres (μm) to 5 millimetres.
6. The shear force-based droplet generation device (100) as claimed in claim 1, wherein an orientation of the first dispenser (112) is adjustable to control a direction of movement of the primary droplet (116) along the y-axis.
7. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the first fluid (118) is a non-Newtonian or a complex fluid.
8. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the predefined angle (134) is between a range of 11 to 100 degrees.
9. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a storage tank externally pressurized using a compressed fluid, and wherein the regulating valve (138) comprises a solenoid valve, such that a pressure within the storage tank and an opening duration of the solenoid valve are controllable to modulate a strength of the micro-jet (136).
10. The shear force-based droplet generation device (100) as claimed in claim 9, wherein the processor (140) is operatively connected to the pressurised fluid source (122) and the regulating valve (138) to control pressurisation of the second fluid (124) and actuation of the regulating valve for modulating the strength of the micro-jet (136).
11. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a pump disposed downstream of the pressurised fluid source, and wherein the regulating valve (138) comprises a flow control valve disposed downstream of the pump, such that operation of the pump according to predefined timings and adjustment of the flow control valve to control a flow rate of the fluid and thereby modulate a strength of the micro-jet (136).
12. The shear force-based droplet generation device (100) as claimed in claim 1, wherein the pressurised fluid source (122) comprises a piston-cylinder arrangement configured as a positive displacement pump, the piston being operable using a motorised arrangement or manually, such that a flow rate of the second fluid and thereby a strength of the micro-jet (136) are adjustable by varying a piston velocity and a stroke length.
13. A method for a shear force-based droplet generation in a submerged fluid environment, comprising:
arranging a first dispenser (112) on a base (110) extending along an x-axis, a y-axis, and a z-axis;
adapting a first nozzle (114) of the first dispenser arranged along the y-axis for dispensing a primary droplet (116) of a first fluid (118) in a dispersed phase via a syringe pump (120) fluidically connected to the first dispenser, such that the primary droplet dispenses off from the first nozzle along the y-axis in the submerged fluid environment;
storing a second fluid (124) in a pressurised fluid source (122);
increasing a pressure of the second fluid in the pressurised fluid source, via a pressuring device (126) operatively connected to the pressurised fluid source;
arranging a second dispenser (130) fluidically connected to the pressurised fluid source, on the base at a predefined distance from the first dispenser along the x-axis;
adapting a second nozzle (132) in the second dispenser, oriented at a predefined angle (134) relative to the first nozzle in a cross-flow configuration, for dispensing a micro-jet (136) of the high pressure second fluid towards the primary droplet of the first fluid, wherein the first fluid and the second fluid are immiscible and have an interfacial surface tension therebetween;
controlling, using a regulating valve (138) arranged between the pressurised fluid source and the second dispenser, a flow of the micro-jet of the high pressure second fluid dispensed from the second dispenser; and
operating the regulating valve, via a processor (140) operatively connected to the regulating valve, for dispensing the micro-jet of the high pressure second fluid upon a surface region (142) of the primary droplet, when a radius (116R) of the primary droplet is less than or equal to a predefined threshold, such that the micro-jet of the high pressure second fluid applies the shear force on the primary droplet for pinching off the primary droplet from the first dispenser.
14. The method as claimed in claim 13, further comprising controlling at least one parameter associated with an interaction between the micro-jet (136) of the high pressure second fluid (124) and the primary droplet (116) to maintain Weber number for switching between modes of pinching off the primary droplet, wherein the modes of pinching off comprises:
a first mode for pinching off the primary droplet into a single-droplet formation, when the weber number is less than 11;
a second mode for pinching off the primary droplet into a multi-droplet formation, when the weber number is between 11 and 350; and
a third mode for pinching off the primary droplet into a spray formation, when the weber number is more than 350.