Claims:1. A device (100) to determine viscosity of a fluid, said device comprising:
afirst component (102), said first component (102) comprising a first cantilever (110) configured at a top surface of afirst supporting element (106), said first cantilever (110) adapted to, upon actuation, vibrate with first vibration attributes; and
a second component (104) comprising a second cantilever (112) configured at a top surface of a second supporting element (108), said second cantilever (112) adapted to vibrate, the second component (104) located such that the first cantilever (110) and the second cantilever (112) are separated by a gap (114),
wherein the gap (114) is adapted to receive the fluid such that the first cantilever (110) and the second cantilever (112) are fluidically coupled through the fluid,
wherein, upon actuation of the first cantilever (110), consequent vibration of the first cantilever (110) enables vibration of the second cantilever (112) with second vibration attributes, and
wherein a correlation of the first vibration attributes and the second vibration attributes is a function of physical attributes of the fluid, the physical attributes being indicative of the viscosity of the fluid.
2. The device as claimed in claim 1, wherein the first cantilever (110) comprises an actuator (152) kinematically coupled tothe first cantilever (110) to actuate said first cantilever (110).
3. The device as claimed in claim 2, wherein the actuator is a layer of piezoelectric material (152), said layer of piezoelectric material (152) adapted to be vibrated by application of an alternating electrical field across the layer of piezoelectric material (152), and wherein vibration of the piezoelectric layer (152) enables vibration of the first cantilever (110).
4. The device as claimed in claim 1, wherein the first vibration attributes are any or a combination of amplitude of vibration and frequency of vibration of the first cantilever (110).
5. The device as claimed in claim 1, wherein the second vibration attributes are any or a combination of amplitude of vibration and frequency of vibration of the second cantilever (112).
6. The device as claimed in claim 1, wherein the physical attributes of the fluid are any or a combination of dynamic viscosity of the fluid and the density of the fluid.
7. The device as claimed in claim 1, wherein the first cantilever (110) comprises:
a bottom electrode layer (156) configured on a substrate (158);
a piezoelectric layer (152) configured on the bottom electrode, said piezo electric layer (152) kinematically coupled to the first cantilever (110); and
a top electrode layer (154) configured on top of the piezoelectric layer (152),
wherein the piezoelectric layer (152) is adapted to be vibrated by application of an alternating electrical field across the piezoelectric layer (152), and
wherein vibration of the piezoelectric layer (152) enables vibration of the first cantilever (110).
8. The device as claimed in claim 1, wherein the device comprises a sensor (608) configured to sense the first vibration attributes and the second vibration attributes of vibration of the first cantilever (110) and the second cantilever (112) respectively.
9. The device as claimed in claim 8, wherein the sensor (608) is a laser Doppler vibrometer.
10. The device as claimed in claim 1, wherein the correlation of the second vibration attributes with respect to the first vibration attributes is determined by a computing device (602) operatively coupled to the device.
11. The device as claimed in claim 1, wherein the physical attributes of the fluid are determined from the function, said function defining a relationship between the correlation and the physical attributes of the fluid.
12. The device as claimed in claim 1, wherein the first cantilever (110) and the second cantilever (112) are self-sensing cantilevers.
13. A method (700) to determine viscosity of a fluid by using the device to determine viscosity of a fluid as claimed in claim 1, said method comprising:
deploying (702) the device (100) in the fluid so as to allow interaction of the fluid with the device;
actuating (704), by an actuator, a first cantilever (110) of the device (100) with first vibration attributes, said first cantilever (110) configured at a top surface of a first supporting element (106), said first cantilever (110) adapted to, upon actuation, vibrate with the first vibration attributes; and
measuring (706), by a sensor, second vibration attributes of a second cantilever (112), said second cantilever (112) configured at a top surface of a second supporting element (108), said second cantilever (112) adapted to vibrate, the second component (104) located such that the first cantilever (110) and the second cantilever (112) are separated by a gap (114),
wherein the gap (114) is adapted to receive the fluid such that the first cantilever (110 and the second cantilever (112) are fluidically coupled through the fluid,
wherein, consequent vibration of the first cantilever (110) enables vibration of the second cantilever (112) with the second vibration attributes, and
wherein a correlation of the first vibration attributes and the second vibration attributes is determined (708) as a function of physical attributes of the fluid, the function being indicative of the viscosity of the fluid (710).
14. A system (600) to determine viscosity of a fluid, said system comprising a device (100) as claimed in claim 1.
, Description:TECHNICAL FIELD
[1] The present disclosure generally relates to the field of viscosity measurement of a fluid. In particular, the present disclosure relates to a device for direct and quick determination of viscosity of a fluid.

BACKGROUND
[2] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[3] The use of fluids as lubricants and coolants in different machines have helped improve the efficiency and extend the operating life of the machines. It is advisable however, to monitor the quality of the fluids in order that they are effective in performing their functions.
[4] Fluid density (?) and viscosity (µ) serve as unique metrics for determining the quality of the fluid in a machine. At a fixed temperature and pressure, the mass-density and the viscosity of the fluid have unique values, for a given fluid. Any variation of the values from the optimum can provide an insight into a current state of the fluid.
[5] For the monitoring of such fluids, a small-scale viscometer is desirable. An approach to measure viscosity of a fluid involves the utilization of effect of density and viscosity on different modes of vibration for the measurement of these fluid properties.
[6] Measurement of fluid viscosity is also an important aspect in medical application such as hemorheology and the monitoring of blood thinning.
[7] Several such devices and method are available in the art. Currently, most of the micro resonator-based viscometers known in the art take advantage of the fact that the quality factor (Q) of the resonator is dependent on the viscosity of the fluid. Different methods, such as logarithmic decrement and 3db bandwidth, are utilised to calculate the Q of the resonator. The Q factor is fitted in a model to estimate the viscosity of the fluid. For 3db bandwidth measurement, the response of the resonator to a frequency sweep is recorded and the 3-dB bandwidth is calculated. In the logarithmic decrement method, the ring-down time of the time series response of the resonator is used for Q-measurement. Both processes are time-consuming and require post-processing of the response to calculate the viscosity. Moreover, the reported error in viscosity estimation can be as large as 20% for these methods.
[8] In the market of fluid property measurement, the only commercially available MEMS-based products are flow meters and density sensors. Many ofthe viscometers in the market are based on traditional methods of measurements such as rotational, falling ball, and capillary. The MEMS viscometers are based on the Q-factor measurements and hence challenging to commercialize.
[9] There is, therefore, a requirement in the art for a means to determine the viscosity of a fluid that is quick, accurate and does not rely on indirect methods. Additionally, there is a requirement for a means to determine the viscosity of a fluid with a compact form factor.

OBJECTS OF THE DISCLOSURE
[10] A general object of the present disclosure is to provide a micro-scale device for determination of viscosity of a fluid.
[11] Another object of the present disclosure is to provide a micro-scale device for direct and quick determination of viscosity of a fluid.
[12] Another object of the present disclosure is to provide a micro-scale device for determination of viscosity of fluid at different shear rates for the fluid.
[13] Another object of the present disclosure is to provide a micro-scale device for determination of viscosity of a fluid that is economical.
[14] Another object of the present disclosure is to provide a method and system for determination of viscosity of a fluid using the micro-scale device.

SUMMARY
[15] The present disclosure generally relates to the field of viscosity measurement of a fluid. In particular, the present disclosure relates to a device for direct and quick determination of viscosity of a fluid.
[16] In an aspect, the present disclosure provides a device to determine viscosity of a fluid. The device includes: a first component, the first component including a first cantilever configured at a top surface of a first supporting element, the first cantilever adapted to, upon actuation, vibrate with first vibration attributes; and a second component including a second cantilever configured at a top surface of a second supporting element, the second cantilever adapted to vibrate. The second component is located such that the first cantilever and the second cantilever are separated by a gap, where the gap is adapted to receive the fluid such that the first cantilever and the second cantilever are fluidically coupled through the fluid. Upon actuation of the first cantilever, consequent vibration of the first cantilever enables vibration of the second cantilever with second vibration attributes. A correlation of the first vibration attributes and the second vibration attributes is a function of physical attributes of the fluid, the physical attributes being indicative of the viscosity of the fluid.
[17] In an embodiment, the first cantilever can include an actuator kinematically coupled to the first cantilever to actuate the first cantilever. In another embodiment, the actuator can be a layer of piezoelectric material, the layer of piezoelectric material adapted to be vibrated by application of an alternating electrical field across the layer of piezoelectric material, and wherein vibration of the piezoelectric layer enables vibration of the first cantilever.
[18] In another embodiment, the first vibration attributes can be any or a combination of amplitude of vibration and frequency of vibration of the first cantilever.
[19] In another embodiment, the second vibration attributes can be any or a combination of amplitude of vibration and frequency of vibration of the second cantilever.
[20] In another embodiment, the physical attributes of the fluid can be any or a combination of dynamic viscosity of the fluid and the density of the fluid.
[21] In another embodiment, the first cantilever can include: a bottom electrode layer configured on a substrate; a piezoelectric layer configured on the bottom electrode, the piezo electric layer kinematically coupled to the first cantilever; and a top electrode layer configured on top of the piezoelectric layer. The piezoelectric layer can be adapted to be vibrated by application of an alternating electrical field across the piezoelectric layer, and vibration of the piezoelectric layer can enable vibration of the first cantilever.
[22] In another embodiment, the device can include a sensor configured to sense the first vibration attributes and the second vibration attributes of vibration of the first cantilever and the second cantilever, respectively. In an exemplary embodiment, the sensor can be a laser Doppler vibrometer.
[23] In another embodiment, the correlation of the second vibration attributes with respect to the first vibration attributes can be determined by a computing device operatively coupled to the device.
[24] In another embodiment, the physical attributes of the fluid can be determined from the function, the function defining a relationship between the correlation and the physical attributes of the fluid.
[25] In another embodiment, the first cantilever and the second cantilever can be self-sensing cantilevers.
[26] In an aspect, the present disclosure provides a method to determine viscosity of a fluid by using the device to determine viscosity of a fluid. The method includes: deploying the device in the fluid so as to allow interaction of the fluid with the device; actuating, by an actuator, a first cantilever of the device with first vibration attributes, the first cantilever configured at a top surface of a first supporting element, the first cantilever adapted to, upon actuation, vibrate with the first vibration attributes; and measuring, by a sensor, second vibration attributes of a second cantilever, the second cantilever configured at a top surface of a second supporting element, the second cantilever adapted to vibrate, the second component located such that the first cantilever and the second cantilever are separated by a gap. The gap is adapted to receive the fluid such that the first cantilever and the second cantilever are fluidically coupled through the fluid. Consequent vibration of the first cantilever enables vibration of the second cantilever with the second vibration attributes. A correlation of the first vibration attributes and the second vibration attributes is determined as a function of physical attributes of the fluid, the function being indicative of the viscosity of the fluid.
[27] In another aspect, the present disclosure provides a system to determine viscosity of a fluid. The system includes the device to determine viscosity of a fluid.
[28] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[29] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.
[30] FIG. 1A illustrates an exemplary representation of a micro-scale viscometer to determine viscosity of a fluid, in accordance with an embodiment of the present disclosure.
[31] FIG. 1B illustrates an exemplary cross-section of a cantilever of the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure.
[32] FIG. 1C illustrates an exemplary representation of the micro-scale viscometer for measurement of viscosity of a fluid, in accordance with an embodiment of the present disclosure.
[33] FIG. 1D illustrates an exemplary representation of a self-sensing cantilever system.
[34] FIG. 2 illustrates an exemplary plot of response of the secondcantilever to actuated vibration of the first cantilever, and the response of the first cantilever, in accordance with an embodiment of the present disclosure.
[35] FIG. 3A illustrates an exemplary plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever, in accordance with an embodiment of the present disclosure.
[36] FIGs. 3B and 3C illustrate an exemplary plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever for different fluid mixtures, in accordance with an embodiment of the present disclosure.
[37] FIG. 4A illustrates an exemplary plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever as a function of kinematic viscosity of the fluid, in accordance with an embodiment of the present disclosure.
[38] FIG. 4B illustrates an exemplary plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever as a function of kinematic viscosity of the fluid, at different frequencies of vibration, in accordance with an embodiment of the present disclosure.
[39] FIG. 5A illustrates an exemplary log-log plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever as a function of kinematic viscosity of the fluid, in accordance with an embodiment of the present disclosure.
[40] FIG. 5B illustrates an exemplary log-log plot of ratio of amplitudes of vibration of the secondcantilever to that of the firstcantilever as a function of kinematic viscosity of the fluid, at different frequencies of vibration, in accordance with an embodiment of the present disclosure.
[41] FIG. 6 illustrates an exemplary module diagram of a system to determine viscosity of a fluid using the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure.
[42] FIG. 7 illustrates an exemplary flow diagram for a method to determine viscosity of a fluid using the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[43] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[44] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[45] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[46] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications, and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[47] The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non – claimed element essential to the practice of the invention.
[48] The present disclosure generally relates to the field of viscosity measurement of a fluid. In particular, the present disclosure relates to a device for direct and quick determination of viscosity of a fluid.
[49] In an aspect, the present disclosure provides a device to determine viscosity of a fluid. The device includes: a first component, the first component including a first cantilever configured at a top surface of a first supporting element, the first cantilever adapted to, upon actuation, vibrate with first vibration attributes; and a second component including a second cantilever configured at a top surface of a second supporting element, the second cantilever adapted to vibrate. The second component is located such that the first cantilever and the second cantilever are separated by a gap, where the gap is adapted to receive the fluid such that the first cantilever and the second cantilever are fluidically coupled through the fluid. Upon actuation of the first cantilever, consequent vibration of the first cantilever enables vibration of the second cantilever with second vibration attributes. A correlation of the first vibration attributes and the second vibration attributes is a function of physical attributes of the fluid, the physical attributes being indicative of the viscosity of the fluid.
[50] In an embodiment, the first cantilever can include an actuator kinematically coupled to the first cantilever to actuate the first cantilever. In another embodiment, the actuator can be a layer of piezoelectric material, the layer of piezoelectric material adapted to be vibrated by application of an alternating electrical field across the layer of piezoelectric material, and wherein vibration of the piezoelectric layer enables vibration of the first cantilever.
[51] In another embodiment, the first vibration attributes can be any or a combination of amplitude of vibration and frequency of vibration of the first cantilever.
[52] In another embodiment, the second vibration attributes can be any or a combination of amplitude of vibration and frequency of vibration of the second cantilever.
[53] In another embodiment, the physical attributes of the fluid can be any or a combination of dynamic viscosity of the fluid and the density of the fluid.
[54] In another embodiment, the first cantilever can include: a bottom electrode layer configured on a substrate; a piezoelectric layer configured on the bottom electrode, the piezo electric layer kinematically coupled to the first cantilever; and a top electrode layer configured on top of the piezoelectric layer. The piezoelectric layer can be adapted to be vibrated by application of an alternating electrical field across the piezoelectric layer, and vibration of the piezoelectric layer can enable vibration of the first cantilever.
[55] In another embodiment, the device can include a sensor configured to sense the first vibration attributes and the second vibration attributes of vibration of the first cantilever and the second cantilever, respectively. In an exemplary embodiment, the sensor can be a laser Doppler vibrometer.
[56] In another embodiment, the correlation of the second vibration attributes with respect to the first vibration attributes can be determined by a computing device operatively coupled to the device.
[57] In another embodiment, the physical attributes of the fluid can be determined from the function, the function defining a relationship between the correlation and the physical attributes of the fluid.
[58] In another embodiment, the first cantilever and the second cantilever can be self-sensing cantilevers.
[59] In an aspect, the present disclosure provides a method to determine viscosity of a fluid by using the device to determine viscosity of a fluid. The method includes: deploying the device in the fluid so as to allow interaction of the fluid with the device; actuating, by an actuator, a first cantilever of the device with first vibration attributes, the first cantilever configured at a top surface of a first supporting element, the first cantilever adapted to, upon actuation, vibrate with the first vibration attributes; and measuring, by a sensor, second vibration attributes of a second cantilever, the second cantilever configured at a top surface of a second supporting element, the second cantilever adapted to vibrate, the second component located such that the first cantilever and the second cantilever are separated by a gap. The gap is adapted to receive the fluid such that the first cantilever and the second cantilever are fluidically coupled through the fluid. Consequent vibration of the first cantilever enables vibration of the second cantilever with the second vibration attributes. A correlation of the first vibration attributes and the second vibration attributes is determined as a function of physical attributes of the fluid, the function being indicative of the viscosity of the fluid.
[60] In another aspect, the present disclosure provides a system to determine viscosity of a fluid. The system includes the device to determine viscosity of a fluid.
[61] In an aspect, the present disclosure provides a device and method which mimics conventional rheometers, where the fluid is subjected to a shear between a moving and a fixed plate of the rheometer. The torque required for maintaining a constant speed (shear rate) is measured, and the shear rate dependent viscosity is calculated. The present device utilizes a system of two cantilevers – one active, one passive. The active cantilever is forced to vibrate while the passive cantilever remains free to respond to the fluid movement around it. The relative amplitude of the passive cantilever provides a measure of the kinematic viscosity of the fluid in which the two cantilevers are immersed. Depending on the frequency of oscillation of the active cantilever, this system can measure the shear rate dependent viscosity by choosing a suitable frequency of oscillation of the active cantilever
[62] FIG. 1A illustrates an exemplary representation of a micro-scale viscometer to determineviscosity of a fluid, in accordance with an embodiment of the present disclosure. The viscometer 100 (herein, also referred to as “device”) can include afirst component 102 and a second component 104. Each of the first component 102 and the second component 104 can include a supporting element (106, 108 respectively) and a cantilever (110, 112 respectively) coupled to the supporting element(106, 108 respectively).
[63] In another embodiment, the first component 102 and the second component 104 are placed such that the free ends of the firstcantilever 110 (herein, also referred to as “active cantilever”) and the secondcantilever 112 (herein, also referred to as “passive cantilever”)are in a vicinity of each other. A gap 114 is provided between the active cantilever 110 and the passive cantilever 112, wherea fluid whose viscosity is to be measured cn be introduced such that the active cantilever 110 and the passive cantilever 112 are fluidically coupled through the fluid.
[64] In an exemplary embodiment, the device 100 can be immersed in the fluid, where the fluid is allowed to also fill the gap 114 between the active cantilever 110 and the passive cantilever 112.
[65] In another exemplary embodiment, the fluid can be introduced to the device such as to fluidically couple the first cantilever 110 and the second cantilever 112 through micro-fluidic channels.
[66] In another exemplary embodiment, the active cantilever 110 and the passive cantilever 112 are provided such that they face one another and are aligned, at a same level.
[67] In another exemplary embodiment, the active cantilever 110 and the passive cantilever 112 are provided adjacent to one another.
[68] FIG. 1B illustrates an exemplary cross-section of a cantilever of the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure.In an embodiment, the active cantilever 110 can be supported on the first supporting element 106. In another embodiment, the active cantilever 110can include a piezoelectric layer 152 sandwiched between a bottom electrode 156 and a top electrode 154. In another embodiment, the piezoelectric layer 152 is kinematically coupled to the active cantilever 110 such that vibration of the piezoelectric layer 152 results in the vibration of the active cantilever 110.
[69] In another embodiment, the electrode assembly including the top electrode 154, the bottom electrode 156 and the sandwiched piezoelectric layer 152 can be configured atop a substrate 158 such as silicon (Si) andsilicon dioxide (SiO2).
[70] In an exemplary embodiment, the material of the piezoelectric layer 152 can include, without limitations, lead zirconatetitanate (PZT), lead magnesium niobate-lead zirconatetitanate (PMN-PZT), lead zirconateniobate-lead zirconatetitanate (PZN-PZT), aluminium nitride (AlN), lithium niobite (LiNbO3), zinc oxide (ZnO), other suitable materials and combinations thereof. The thickness of the piezoelectric layer 152 can depend on the piezoelectric material and the specific requirement of a particular application.
[71] In another exemplary embodiment, the bottom electrode 156 and the top electrode 154 can be a thin layer of conducting materials such as, without limitations, gold, silver, platinum, palladium, copper, aluminium, an alloy comprising one or more of such metals and non-metallic conductors such as graphite, graphene and carbon nanotubes.
[72] In an exemplary embodiment, the cross-section of the passive cantilever 112 (not shown) can have a similar configuration as that of the active cantilever 110 described above.
[73] In another exemplary embodiment the piezoelectric layers of the cantilevers (110, 112) can be patterned such that the piezoelectric layer of the active cantilever 110 can simultaneously actuate and the sense the active cantilever 110, and the piezoelectric layer of the passive cantilever 112 can act as a sensor to sense the passive cantilever 112.
[74] In an exemplary embodiment, each of the cantilevers (110, 112) can be initially deposited on a block, the block. An area under the cantilevers (110, 112) can be etched away using suitable techniques to realise the cantilevers (110, 112). A part of the block remains to act as the supporting elements (106, 108) under the cantilevers (110, 112 respectively).
[75] Referring to FIGs. 1A and 1B, the device 100 is implemented by introducing the fluid at the gap 114 between the active cantilever 110 and the passive cantilever 112 such that the active cantilever 110 and the passive cantilever 112 are fluidically coupled.
[76] In an embodiment, the active cantilever 110 is actively actuated to vibrate or oscillate with first vibration attributes by actuating the piezoelectric layer 152 (herein, also referred to as “actuator”). An alternating electric field applied across the piezoelectric layer 152 causes the piezoelectric layer 152 to vibrate at the frequency of the applied electric field, which then causes the active cantilever 110 to vibrate with the first vibration attributes. The vibration or motion of the active cantilever 110 causes a corresponding motion in the surrounding fluid, which results in a time-varying vibration force being transmitted to the passive cantilever 112 through the fluid medium which is facilitating fluidic coupling of the active cantilever 110 and the passive cantilever 112, thereby causing the passive cantilever 112 to vibrate or oscillate with second vibration attributes. The vibratory force experienced by the passive cantilever 112 thus, is a function of physical attributes of the fluid medium that allows for transmission of motion through the fluid medium.
[77] In an exemplary implementation of the present disclosure, the physical attribute of interest is the kinematic viscosity of the fluid medium, defined as a ratio of dynamic viscosity of the fluid to its density (µ/?).
[78] In another exemplary embodiment, the first vibration attributes and the second vibration attributes can be the amplitude and the frequency of vibration of the active cantilever 110 and the passive cantilever 112, respectively.
[79] In another embodiment, the relative amplitude of the passive cantilever 112 can provide a measure of the kinematic viscosity of the fluid, whereupon the dynamic viscosity of the fluid can be calculated given that the density of the fluid is known.
[80] In another embodiment, since the resonant peaks of the cantilevers depend on density of the fluid, the density of the fluid can be calculated using the shift observed in the resonant peaks of the active cantilever 110 and the passive cantilever 112.
[81] In another embodiment, the device 100 can be provided with sensors (not shown in figure) which can be coupled with the active cantilever 110 and the passive cantilever 112 to measure the first vibration attributes and the second vibration attributes of the active cantilever 110 and the passive cantilever 112 respectively. The responses of the active cantilever 110 and the passive cantilever 112 can be measured at their corresponding tips using a laser Doppler vibrometer (LDV).
[82] In another embodiment, the device 100 can be operatively coupled with a computing device (reference ofFIG. 6). The computing device can include a processor and a memory operatively coupled with the processor. The memory can include a set of instructions executable by the processor to determine the viscosity of the fluid. The computing device can actuate the active cantilever to vibrate with first vibration attributes, and the computing device can receive the second vibration attributes of the passive cantilever 112. Based on the first vibration attributes and the second vibration attributes, the computing device is configured to determine a correlation between the first vibration attributes and the second vibration attributes. The computing device is further configured to determine the kinematic viscosity of the fluid from a function defining a relationship between the correlation and the kinematic viscosity of the fluid.
[83] In another embodiment, the device 100 of the present disclosure is tested using a sample fluid such as a mixture of glycerol and water. The concentration of the sample mixture is varied to obtain multiple test datasets.
[84] FIG. 1C illustrates an exemplary representation of the micro-scale viscometer for measurement of viscosity of a fluid, in accordance with an embodiment of the present disclosure.
[85] The use of LDV requires the use of bulky and expensive equipment, which can be a limitation to effective commercialisation.
[86] In an exemplary embodiment, the device 100 of the present disclosure can use self-sensing cantilever systems to enable all-electrical measurements of vibration.
[87] FIG. 1D illustrates an exemplary representation of a self-sensing cantilever system.
[88] FIG. 2 illustrates an exemplary plot of response of the second cantilever to actuated vibration of the first cantilever, and the response of the first cantilever, in accordance with an embodiment of the present disclosure. The plot represents the frequency of vibration of the actuated active cantilever (202) and the frequency of vibration of the passive cantilever (204) in response, when the device is immersed in a 10% solution of glycerol in water.
[89] FIG. 3A illustrates an exemplary plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever, in accordance with an embodiment of the present disclosure. The plot represents the amplitude ratio when the device is immersed in a 10% solution of glycerol in water.
[90] FIGs. 3B and 3C illustrate an exemplary plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever for different fluid mixtures, in accordance with an embodiment of the present disclosure. In an embodiment, the fluid mixture is varied from a 10% solution of glycerol in water to a 70% solution of glycerol in water. It can be observed that the amplitude ratio has a peak at the same frequency as the resonant frequency of the passive cantilever (ref. FIG. 2). Since resonant frequency of the cantilever depends on the density of the fluid, the peak of the amplitude ratio curve can provide information pertaining to the density of the fluid.
[91] The relative amplitude of the passive cantilever is a measure of the amount of force acting upon it, which has a direct correlation with the kinematic viscosity of the fluid. Increasing the concentration of glycerol in water increases the density and viscosity of the fluid. The corresponding increase in kinematic viscosity of the fluid can be measured by the amplitude ratio curves away from the corresponding peaks, as observed from FIG. 3C. The described process to measure the kinematic viscosity of the fluid does not require frequency sweeps and peak fitting for Q – measurement, thereby enabling quicker measurement of kinematic viscosity.
[92] FIG. 4A illustrates an exemplary plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever as a function of kinematic viscosity of the fluid, in accordance with an embodiment of the present disclosure. The kinematic viscosity of the fluid is obtained from literature, and it can be observed that the curve (402) follows a power law (axb). the corresponding fitting of the measured amplitude ratio is also shown (404).
[93] FIG. 4B illustrates an exemplary plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever as a function of kinematic viscosity of the fluid, at different frequencies of vibration, in accordance with an embodiment of the present disclosure.
[94] The power law dependence of the plot of amplitude ratio allows for linearization of the curve when the curve is plotted on a log-log scale. The linearization facilitates easier calibration of the device in a practical setting.
[95] FIG. 5A illustrates an exemplary log-log plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever as a function of kinematic viscosity of the fluid, in accordance with an embodiment of the present disclosure.
[96] FIG. 5B illustrates an exemplary log-log plot of ratio of amplitudes of vibration of the second cantilever to that of the first cantilever as a function of kinematic viscosity of the fluid, at different frequencies of vibration, in accordance with an embodiment of the present disclosure.
[97] FIG. 6 illustrates an exemplary module diagram of a system for to determine viscosity of a fluid using the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure. The system 600 includes the device 100 and a computing device 602 operatively coupled to the device 100. The computing device 602 can include a processor 604 and a memory 606 operatively coupled with the processor 604. The memory 606 can include a set of instructions executable by the processor 604 to determine the viscosity of the fluid.
[98] In an embodiment, the computing device 602 is configured to actuate the active cantilever to vibrate with first vibration attributes, and the computing device 602 is configured to receive the second vibration attributes of the passive cantilever 112 upon vibration of the second cantilever.
[99] In another embodiment, the first vibration attributes and the second vibration attributes can be measured using a sensor 608 coupled with the device 100.
[100] In another embodiment, based on the first vibration attributes and the second vibration attributes, the computing device 602 is configured to determine a correlation between the first vibration attributes and the second vibration attributes.
[101] In another embodiment, the computing device 602 is further configured to determine the kinematic viscosity of the fluid from a function defining a relationship between the correlation and the kinematic viscosity of the fluid.
[102] FIG. 7 illustrates an exemplary flow diagram for a method to determine viscosity of a fluid using the proposed micro-scale viscometer, in accordance with an embodiment of the present disclosure. The method 700 comprises,
• 702 – deploying the device in the fluid so as to allow interaction of the fluid with the device;
• 704 – actuating, by an actuator, the firstcantilever to vibrate with the first vibration attributes, wherein, upon actuation of the firstcantilever, consequent vibration of the firstcantilever enables vibration of the secondcantilever with second vibration attributes;
• 706 – measuring, by a sensor, second vibration attributes of the second cantilever;
• 708 – determining a correlation of the first vibration attributes and the second vibration attributes; and
• 710 – determining the kinematic viscosity of the fluid from a function defining a relationship between the correlation and the kinematic viscosity of the fluid.
[103] Thus, the present disclosure provides a device and a method for direct and quick determination of viscosity of a fluid in which the device can be immersed. The device includes afirst component and a second component, each provided with an active cantilever and a passive cantilever, respectively. The active cantilever and the passive cantilever are placed facing one another. The active cantilever is actuated to vibrate. The vibration causes motion of the surrounding fluid and eventually the vibration motion is transmitted to the passive cantilever to vibrate the second cantilever. The relative amplitude and frequency of vibration of the passive cantilever with respect to the active cantilever is a function of eh kinematic viscosity of the fluid.
[104] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive patent matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “includes” and “including” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practised with modification within the spirit and scope of the appended claims.
[105] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE DISCLOSURE
[106] The present disclosure provides a micro-scale device for determination of viscosity of a fluid.
[107] The present disclosure provides a micro-scale device for direct and quick determination of viscosity of a fluid.
[108] The present disclosure provides a micro-scale device for determination of viscosity of fluid at different shear rates for the fluid.
[109] The present disclosure provides a micro-scale device for determination of viscosity of a fluid that is economical.
[110] The present disclosure provides a method and system for determination of viscosity of a fluid using the micro-scale device.