FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
Title:
DEVICE TO CONTROL PARTICLE COLLECTION IN
CONTINUOUSLY FLOWING SYSTEM
AND METHOD THEREFOR
Applicant: XXX
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to sorting, extraction and collection of suspended microparticles in a continuously flowing liquid suspension. Particularly, the present invention relates to modifying the cut-off characteristics of the system to enable collection of microparticles of specific sizes suspended in a continuously flowing liquid suspension.
BACKGROUND OF THE INVENTION
When an open liquid volume is subjected to periodic vibrations, capillary waves are formed at the liquid-air interface. For instance, as seen in Figure 1, a sessile water droplet, pinned at the contact line, forms a standing capillary wave at the water-air interface. The presence of microparticles within such open volume of liquid demonstrates several interesting effects. Particles either exhibit migration towards certain locations over multiple cycles to be collected stably or they exhibit a continuous circulation in the liquid bulk. This behaviour of the movement of microparticles forms the basis of the present invention and is readily observed in particle suspensions in horizontally actuated open rectangular chambers (Figure 3).
PRIOR ART
The basic particle collection technique is based on a very recently understood mechanism, where the first publication dates back to 2010. These include the papers entitled:
1) "Collection of suspended particles in a drop using low frequency vibration", by James Whitehill, Adrian Neild, Tuck Wah Ng, and Mark Stokes and published in Applied Physics Letters 96, 053501 (2010),
2) "Nanoparticle manipulation within a microscale acoustofluidic droplet", by James David Whitehill and Ian Gralinski and Duncan Joiner and Adrian Neild and published in J Nanopart Res, 14:1223 (2012),
3) "Bioparticles assembled using low frequency vibration immune to evacuation drifts", by Fenfen Shao, James David Whitehill, Tuck Wah

Ng, published in the Rev. Sci. Instrum. 83, 085115 (2012),
4) "The mechanics of microparticle collection in an open fluid volume undergoing low frequency horizontal vibration" by Prashant Agrawal, Prasanna S. Gandhi, and Adrian Neild and published in the Journal of Applied Physics 114, 114904(2013),
5) "Quantification and comparison of low frequency microparticle collection mechanism in an open rectangular chamber" by Prashant Agrawal, Prasanna S. Gandhi, and Adrian Neild and published in the Journal of Applied Physics 115, 174505 (2014), and
6) "Microparticle Response to Two-Dimensional Streaming Flows in Rectangular Chambers Undergoing Low-Frequency Horizontal Vibrations" by Prashant Agrawal, Prasanna S. Gandhi, and Adrian Neild and published in Physical Review Applied 2, 064008 (2014).
The Paper 1) above, demonstrated the movement of micrometer sized glass particles underneath standing capillary waves in microliter volume sessile droplets. The study was later extended to collect sub-micron sized particles as discussed in Paper 2 above. Further investigation into a particle's movement in horizontally and vertically excited rectangular chambers established the governing principle and the critical factors behind the particle's migration as discussed in Papers 4 and 5 above. Also, the cut-off characteristics of the particle were identified, for a given chamber dimension and vibration amplitude, by the set of particle radius and density values above which all particles collect stably in defined locations, or, continue to swirl within the liquid bulk as discussed in Paper 6 above. However, all the above literature concerns with microparticle manipulation in a non-flowing system, wherein the liquid-particle suspensions are either in the form of sessile droplets or contained in an open 'chamber'.
There are many patents, using different techniques, related to microparticle separation for the technique employed for the separation/sorting/focusing of microparticles. Broadly, these methods can be classified as (1) Active methods, which employ external fields for manipulating particles, and (2)

Passive methods, which do not use any external fields, but rely on hydrodynamic interactions to manipulate particles. Passive methods include techniques such as: Pinched Flow fractionation, Hydrodynamic Filtration, Dynamic Lateral displacement (DLD), Hydrophoresis, Sedimentation and Fluid inertial effects, while, active manipulation methods employ Magnetic fields, Optical fields, Electric fields and Acoustic fields.
In terms of their commercial applicability, techniques such as membrane filtration, sedimentation, filtration, and centrifugation are well established for base-liquid cleaning applications. Specifically, ultrafiltration systems (use membranes) are used extensively for water purification in equipment ranging from household water-purifiers to large scale sanitation plants.
Moreover, in recent times, inertial microfluidic systems (membrane-less) have also demonstrated large scale water filtration capabilities developed by Palo Alto Research Center Incorporated, formerly Xerox (PARC).
In regards to particle separation, centrifugation is widely used across a large range of system scales, ranging from industrial process plants to bench-top laboratory units.
Further, some companies such as Biosep and Sonosep offer commercial products, using acoustic waves, which function to separate cells from the base fluid flow (or acoustic cell retention systems).
In regards to the capillary wave based particle manipulation system, the prior literature, and related knowledge is limited to non-flowing systems. The present knowledge relating to the behavior of microparticles underneath capillary waves, which is also relevant to this invention, is detailed below:
With the reduction in particle sizes, these streaming fields demonstrate a tendency to trap particles and hinder their collection in stable locations (Figure 2a and 3f exhibit particles trapped in streaming flows). A chamber which vibrates with a predefined frequency and amplitude, has a specific flow field,

which shows a distinguishing behavior towards the particle movement.
The existing literature and knowledge, relating to this mechanism, is concerned with particle collection in non-flowing systems.
Accordingly, the particles above a predefined radius and density collect in stable locations and the particles below this predefined value keep-on swirling in the streaming flows. This value of particle radius and density which distinguishes between these two behaviors is referred to as the 'cut-off value'.
Further, in Paper 6 mentioned above, different collection characteristics of silica particles (diameter 1 urn) in chambers of different dimensions at the same vibration amplitude are discussed which demonstrates the two behaviors on either side of the cut-off characteristics.
In the first case having a chamber length of 4 mm and chamber depth of 0.25 mm, the particles primarily keep-on swirling due to the streaming fields. In a second case having a chamber length of 8 mm and chamber depth of 0.1 mm at the same vibration amplitude, a complete particle collection occurs at stable locations in the chamber.
The simulated flow field and expected collection locations are depicted in Figure 4. The ability of this capillary wave based system demonstrating different particle movement behavior for particles of different sizes for a given chamber geometry and vibration amplitude can be easily utilized to achieve a continuous size based particle sorting.
Moreover, the above literature has been explored exclusively for non-flowing systems and does not talk of continuous flow of liquid-microparticles suspensions. DISADVANTAGES WITH THE PRIOR ART
The existing techniques utilized for sorting/extracting/focusing microparticles have several limitations. In general, although passive

methods are simple to operate, they offer low control over a particle's trajectory and offer low resolution during the separation process. Active methods do resolve the above issues with passive methods, but require additional complexity in terms of device setup and operation.
A brief summary of the advantages and disadvantages of active and passive methods is tabulated below.
Active Methods:

Method Functioning Separation Criterion Advantages Disadvantages
Magnetic Magnetic fields Size Magnetization Simple Limited applicability

inexpensive Relatively weak force

Throughput/specificity trade off
Optical Optical field gradients Size High spatial resolution Expensive setup and operation

Refractive index High specificity Low throughput

High forces cell damage

High response photo bleaching
Sensitive experimental setup
Electric field gradients Size High throughput Expensive

Polarizability Multiple fabrication steps
Di-
High voltage/power
electrophoresis
local heating
(DEP)
dependence on medium conductivity

electrode contact damage
Pressure gradients Size High throughput High power requirements
for high volume, causing
heating which inhibits
collection

Density Large forces

Acoustic
Compressibility versatile (for
multiple applications) Smaller particles need
smaller wavelengths,
therefore, difficult particle
handling

Easy integration with LOC

bio-compatibility

simple setup and operation
Passive Methods:

Method Functioning Separation Criterion Advantages Disadvantages
Pinched flow Laminar flow Size Simple operation Difficult submicron particle collection

fractionation
pinching
Hydrodynamic Laminar flow Size Simple operation Resolution/efficiency trade-off
Diffusion and obstacles Size Fast, simple, cheap clogging
Filtration


damage to filtrate



reduced efficiency over time
Dynamic Obstacle array Size Sub-micron particle separation Difficult fabrication
Lateral
displacement
(DLD)

Separation resolution better at higher flow rates

Hydrophoresis Presure
gradient from
slanted
obstacles Size Simple setup,
control over
particle movement Device specific, therefore less flexible
Sedimentation gravity Size, Density Simple setup Slow, low control
Inertial Lift forces Size High throughput Very low sample concentration
Microfluidics
Simple operation
As mentioned earlier, particle manipulation in capillary wave based system has been restricted to non-flowing systems which restricts its usage for batch particle manipulation. In case of a continuous flowing system, the flow rate becomes an additional factor which alters the cut-off characteristics of the system. Therefore, there is a need felt for modifying the cut-off characteristics to enable collection of microparticles of specific sizes suspended in a continuously flowing liquid suspension.
TECHNICAL SOLUTION
Active manipulation methods offer an advantage over the above in terms of particle resolution and control over its trajectory, but have certain limitations as well. For instance, magnetophoresis and electrophoresis are limited to only magnetic and charged particles, respectively; optophoresis requires an expensive setup and operation which is highly sensitive, and results in low throughput; di-electrophoresis involves multiple fabrication steps and high voltages; acoustophoretic systems are most versatile in this regard but face heating issues during continuous operation while processing bulk samples.
The present invention is conceived to explore the sorting and separation of microparticles in the presence of a transverse flow, wherein microparticles of

two different sizes are continuously inserted in the chamber. Further, the macroscale device according to the present invention can be utilized for a high volume focusing, concentration and size-based sorting of microparticles.
So, by altering the chamber dimensions and the vibration amplitude, the cut-off characteristics can be suitably modified to enable the collection of particles of a predefined size, which is exploited for particles focusing/sorting/extraction.
OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a continuous high volume concentration (or focusing) of microparticles in a sample of different sizes, densities and surface chemistries (i.e. the type of molecules attached to their surface).
Another object of the present invention is to provide a continuous high volume sorting of microparticles of different diameter or density in a sample.
Still another object of the present invention is to provide a continuous extraction of microparticles of a smaller size or density from a sample of particles of different size distributions or density distributions.
Yet another object of the present invention is to modify the cut-off characteristics, by controlling the vibration amplitude to extract microparticles of specific sizes (or densities) in continuously flowing suspensions.
A further object of the present invention is to provide a macroscale device to be utilized for a high-volume focusing, concentration, sorting and extraction of microparticles based on particle size and density.

A further object of the present invention is to provide a macroscale device to be utilized for a high-volume focusing and concentration of microparticles based on their surface chemistry.
Still further object of the present invention is to provide method for sorting and separating microparticles in a transverse flow, while continuously inserting microparticles of two different sizes/densities in the chamber.
These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a device provided with modified channel for focusing, sorting, extraction and collection of the microparticles by their size or density. In accordance with the present invention, there is also provided a method for sorting, focusing and separating the microparticles by their size or density. The device comprises:
- at least one vibrating chamber including at least one open channel
having at least one inlet disposed at one longitudinal end, or laterally at one end, or at the floor of the open channel at one end thereof and a plurality of outlets disposed at or adjacent the other longitudinal end thereof;
- at least one holder for holding the vibrating chamber;
- at least one EM (electromagnetic) vibrator or a motor, connected through a crank-shaft mechanism, for vibrating the chamber;
- at least one pump for maintaining a continuous flow of the liquid-particles suspension in the open channel;
wherein the chamber is vibrated in a direction transverse to the flow of the liquid-particle suspension continuously introduced in the open channel in

through the inlet and the large particles are extracted from at least one central outlet and the remaining based liquid and/or particles are extracted through the side outlet/s.
Typically, one outlet is provided central at the end opposite the inlet end of the OPEN channel and at least one pair of side outlets are provided adjacent the central outlet.
Typically, the central outlet is provided at any position along the length of the OPEN channel, preferably towards the longitudinal end away from the inlet end of the OPEN channel and at least one pair of side outlets is provided and wherein the central outlet and side outlets both are uniformly disposed about the same longitudinal cross-section of the OPEN channel.
Typically, at least one pair of central outlets and at least three side outlets are configured at any position along the length of the OPEN channel, preferably towards the longitudinal end away from the inlet end of the OPEN channel and the outlets being uniformly disposed about a predetermined longitudinal cross-section of the OPEN channel.
Typically, a plurality of OPEN channels are disposed in parallel along the longitudinal direction thereof and connected to a common inlet, the OPEN channels being vibrated at the same frequency and amplitude for high-volume separation of particles.
Typically, the plurality of OPEN channels is vibrated at different frequencies and/or amplitudes for high-volume separation of particles.
Typically, a plurality of OPEN channels is disposed in series and vibrated at same and/or different frequencies and/or amplitudes for sample refinement or multiple particle sorting; the first OPEN channel is connected to a main inlet and the outlet of the first OPEN channel is connected to the inlet of the second OPEN channel via a pump.

Typically, at least one central outlet is provided at the longitudinal end disposed opposite the inlet end and one side outlet each is uniformly disposed about the central outlet at the same end; the central outlet for extracting larger particles and side outlets for extracting smaller particles.
Typically, the inlet is configured in the top, side or bottom and the outlets are configured in the floor of the OPEN channel.
Typically, the inlet is configured in the top of the OPEN channel and the outlets are configured in the sides of the OPEN channel.
Typically, the OPEN channel is configured with a plurality of floor levels; the inlet end floor level disposed at a lower level than the floor/s at the other longitudinal end of the OPEN channel restricting the flow of heavier particles by means of subsequently disposed stepped floor/s; and wherein a central outlet is provided adjacent the lower floor level of the inlet end floor for extracting restricting the flow of heavier particles; and at least one outlet is configured in each subsequent higher level floor of the OPEN channel for extracting smaller particles.
Typically, the OPEN channel is configured with the following dimensions:
(a) Length in a range of 5 to 100 mm, preferably 20 to 40 mm, more preferably 30 mm;
(b) Width in a range of 1 to 20 mm, preferably 6 to 8 mm, more preferably 8 mm;
(c) Depth in a range of 0.1 to 10 mm, preferably 0.1 to 1 mm, more preferably 0.2 mm.
In accordance with the present invention, there is also provided a method for controlling particle collection in a continuously flowing multi-particle liquid-particle suspension system by means of the aforementioned device.

The method comprises the steps of:
- mounting the chamber containing OPEN channel/s on the holder thereof;
- supplying the OPEN channel/s with a multi-particle liquid-particle suspension having particles of at least 0.01 μm and up to 100 μm or more, at a flow rate of 50 to 10000μl/min, preferably 600 μl/min;
- vibrating the OPEN channel/s at a frequency of 1 to 200 Hz, preferably
12 to 15 Hz, more preferably 13 Hz and with an amplitude of 20 to 1000 μm, preferably 200 μm;
- creating a periodic first order velocity field accompanying a streaming field including steady second order vortices
- focusing the larger/heavier particles, preferably over multiple cycles
underneath a capillary wave node by means of the first order velocity field;
- sorting the particles by dragging away the smaller/lighter particles from the collection locations into the bulk of the multi-particle liquid-particle suspension by means of the streaming field; and
- extracting larger/heavier particles from the central outlet and smaller/lighter particles from the side outlets.
Typically, the open channel is made of Polydimethylsiloxane (PDMS).
Typically, the open channel is made of any of the materials including glass, metal, plastic, using additive methods such as casting or through machining processes such as milling and shaping.
Typically, the open channel is made by 3-D printing.
In accordance with the present invention, there is also provided a method for fabricating a PDMS channel, the method includes the steps of:

(i) fabricating a mold through a cut-out from scotch tape/paper;
(ii) affixing the mold to the base of a rectangular tank for subsequently pouring PDMS over the mold;
(iii) heat treating PDMS filled tank at approximately 80°C for a predetermined duration until solidification of PDMS;
(iv) removing the solidified PDMS carefully from the base to obtain the desired channel shape; and
(v) adding inlets and outlets as punched holes to serve as connections for the tubing.
Typically, the mold is fabricated through 3D printing.
Typically, the mold is fabricated through fabrication processes, such as milling and shaping.
Typically, the inlets and outlets are added by bonding separate PDMS blocks containing holes which serve as connections for the tubing.
Typically, the holes are incorporated within the mold configuration itself.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings, which include:
Figure 1 shows the formation of capillary waves at the liquid-air interface of a vibrating drop as disclosed in the above mentioned paper [1].
Figures 2a to 2d show the collection of particles in vertically vibrating drop, as discussed in the above-referred paper.
Figures 3a to 3f show the vibration of an open horizontally actuated rectangular chamber filled, with water disclosed in above mentioned paper [4].

Figures 4a and 4b show different collection characteristics of silica particles (1 μm) in the different chambers as discussed in the above mentioned paper [6].
Figure 5 shows the complete experimental setup of the device in accordance with the present invention.
Figure 5a shows the basic idea of subjecting the closed chamber to a transverse flow.
Figure 5b shows the collection of silica particles in Polydimethylsiloxane (PDMS) channel as observed experimentally in a 3D representation thereof.
Figure 5c shows the open channel device shown in Figure 5.
Figure 6a and 6b show top and bottom view of another configuration of the device in accordance with the present invention provided with modified channel for sorting/extraction of the microparticles by their size or density.
Figure 7a and 7b show another view of the device setup in accordance with the present invention provided with a modified set-up for sorting/extraction of the microparticles by their size or density.
Figure 8 shows the dimensions of the exemplary open channel device of Figure 7b.
Figure 9a depicts the movement of polystyrene (red) and silica (white) particles.
Figure 9b shows the first order periodic velocity field in the z direction (surface plot) and steady streaming field (arrow plot) in the chamber in the x-z plane
Figure 9c shows the simulated movement of the particles in the x-z plane.

Figure 10a shows the particle size distribution results of Silica particles obtained at the side outlet configured in the sorting-cum-extraction device in accordance with the present invention.
Figure 10b shows the particle size distribution results of Silica and Polystyrene particles obtained at the central outlet configured in the sorting-cum-extraction device in accordance with the present invention.
Figure 10c shows the particle size distribution results of Silica and Polystyrene particles obtained at the central outlet configured in the sorting-cum-extraction device in accordance with the present invention.
Figure 11 and 11b demonstrates results for the size based extraction device for two sets of particles at different excitation amplitudes at side outlets.
Figure 12a to 12h show a few exemplary embodiments of the open channel configurable in accordance with the present invention.
Figure 13a to 13c depict the fabrication procedure for the open channels using PDMS.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The device in accordance with the present invention for controlling microparticle collection by sorting, focusing and separating the same in an open chamber in a continuously flowing suspension is described in details in the following:
Figure 1 shows the side view of the formation of capillary waves at the liquid-air interface of a vertically vibrating drop, e.g. capillary waves are formed at the water-air interface at specific frequencies. A water drop W is vibrating in air in direction V indicated by double-headed arrow and capillary wave C is formed at the water-air interface. This causes the suspended microparticles P1 (at the center), P2 (slightly away from the center) present in the water drop to accumulate at different locations depending on their particle size and amplitude of vibrations. This is demonstrated here via an approach of vertically vibrating

droplet forming resonant shapes on the liquid-gas interface. This results in particles ranging in size from 40-120 urn collected predominantly at the solid-liquid interface due to a hydrodynamic focusing mechanism developed in multiple cycles, as shown in Figures 2a to 2d discussed below.
Figure 2a shows the top view of the particles (10μm to 30 μm) trapped in streaming flows in a vertically vibrating drop W shown in Figure 1. The microparticles are seen scattered throughout the water drop. As the capillary waves are formed, some particles collect in the form of a ring, while other smaller particles are trapped in the streaming flows which prevent their collection in stable locations as represented by the encircled groups 10 and 12 in streaming flows.
Figure 2b shows the final collected pattern of microparticles having diameter 42 μm in the form of a single substantially visible circular ring 14 in the vibrating water drop W. The larger sized particles here remain unaffected by the streaming flows and collect in stable locations.
Figure 2c shows the final collected pattern of microparticles having diameter 60 μm in the form of a single substantially visible circular ring 14 in the vibrating water drop W. The larger sized particles here remain unaffected by the streaming flows and collect in stable locations.
Figure 2d shows the final collected pattern of microparticles having diameter 116 um in the form of a single substantially visible circular ring 14 in the vibrating water drop W. The larger sized particles here remain unaffected by the streaming flows and collect in stable locations.
Figure 3 shows the vibration of an open horizontally actuated rectangular chamber 20 filled with water and collection of the different microparticles due to the presence of 2 wavelength capillary waves 22, 24 at the water-air interface. The figure shows the shape of the water-air interface (i.e., the capillary wave) formed at different time t after commencement of horizontally actuated vibrations (vibration direction V) of the chamber 20, i.e. at t = 0, t = T/4, t = T/2 and t=3 T/4 respectively.

Figure 3a shows a top view of the collection profile in x-y plane in an open horizontally actuated rectangular chamber filled with water and glass particles of 40 μm diameter, vibration amplitude of 40 |a.m and within collection time of 4 seconds. The particles are accumulated in two thick layers disposed substantially in the middle of the chamber length.
Figure 3b shows a top view of the collection profile in x-y plane of an open horizontally actuated rectangular chagiber filled with water and a mixture of PS (polystyrene) particles of 30 μm diameter, vibration amplitude of 24 μm particle size and within collection time of 23 seconds. The particles are accumulated in two thick layers with distinct distributions substantially around the mid-length of the chamber.
Figure 3c shows another top view of the collection profile in x-y plane of an open horizontally actuated rectangular chamber filled with water and a mixture of PS (polystyrene) particles of 20 |am diameter, vibration amplitude of 25μm and within collection time of 35 seconds. Here, the particles are accumulated in two thick layers with more distinct distributions substantially around chamber mid-length.
Figure 3d shows a further a top view of the collection profile in x-y plane of an open horizontally actuated rectangular chamber filled with water and a mixture of PS (polystyrene) particles of 6 μm diameter, vibration amplitude of 25 μm particle size and within collection time of 62 seconds. Here, the particles are accumulated in two coarser layers with hazy distributions on a side of chamber.
Figure 3e again shows a top view of the collection profile in x-y plane of an open horizontally actuated rectangular chamber filled with water and a mixture of Silica particles of 4.74μm diameter, vibration amplitude of 25 μm and within collection time of 26 seconds and some particles are accumulated in two distinct middle bands along mid-length of the chamber and the remaining particles throughout the chamber.

Figure 3f shows a later top view of the collection profile in x-y plane of an open horizontally actuated rectangular chamber filled with water and a mixture of Silica particles of 1 μm diameter, vibration amplitude of 20 μm and within collection time of 144 seconds. Here, microparticles are distributed in two coarse bands centered about the mid-length of the chamber. However, the flow field generated by these periodic or time-dependent capillary waves also exhibits a steady or time-independent rotational flow, which is called 'acoustic streaming'. Due to lower particle sizes, the streaming flow fields again demonstrate a tendency to trap particles and hinder their collection in stable locations due to particle trapping in streaming flows as already shown in Figures 2a. Therefore, any chamber vibrating with a predefined frequency and amplitude has a specific flow field, which shows a differentiating behavior towards particle movement according to their particle sizes. The particles above a specific particle size (radius) and density are collected in stable locations and the particles below this specific radius or density go on swirling in the streaming flows. This specific value of particle radius and density distinguishing between these two particle collection behaviors is termed as the cut-off value. It is possible to modify the cut-off characteristics to enable the collection of particles of a specific size in a desired location by appropriately altering the chamber dimensions and the vibration amplitude.
Figures 4a shows collection characteristics of silica particles (1 μm) in a chamber having a chamber length of 4 mm and depth of 0.25 mm.
Figures 4b shows the collection characteristics of silica particles (1 μm) in another chamber with different dimensions (chamber length: 8 mm and depth: 0.1 mm), however, having the same vibration amplitude. Simulated flow-field 30 and expected microparticle collection locations 32 are also marked on top of both the chambers. As discussed above, the capillary wave based system demonstrating different particle movement behavior for microparticles of different sizes for a given chamber geometry and vibration amplitude utilized to achieve a size based particle sorting were studied only for non-flowing systems. Therefore, the present invention proposes in the

following to carry out particle sorting in the presence of a transverse flow, where microparticles of two different sizes are continuously introduced in the channel. Further, a macroscale device is proposed in accordance with the present invention for a high-volume focusing, concentration and size-based sorting of the different sizes of microparticles present in a suspension contained therein. Moreover, as against the non-flowing systems of the prior art literature, the present invention concerns controlling the particle collection in continuously flowing systems, in which a channels is configured having a continuous inflow and outflow of particles and liquid.
Figure 5 shows the complete set-up of the basic device in accordance with the present invention. It includes an open channel 100, an electromagnetic vibrator 110, a channel holder 120 and a syringe pump 130. This device 100 enables a continuous focusing of particles, such that a high-concentration of the particles is obtained at the central outlet 104 and the side outlets 105 (not shown) carry the remaining base liquid and/or particles.
Figure 5a shows the basic idea of subjecting the closed channel 100 to a transverse flow TF, which is continuously introduced through inlet 102 of the open channel having an outlet 104 for obtaining a focused line of particles. A water based fluid containing the microparticles is present in the area 108.
Figure 5b shows the collection of silica particles in an open channel as observed experimentally in a 3D representation of the same. The particles converge to the center 106 of the open channel 100 by vibrating it in the direction of vibration V.
Figure 5c shows an enlarged view of the open channel 100 in accordance with the present invention. The open channel 100 is vibrated by electromagnetic vibrator 110 (Fig. 5), while particles are continuously fed through the inlet 102 and focused particles are taken out of the outlet 104, after particles converge at the center 106 in the water based fluid 108.

Figure 6a shows top view of another configuration 200 of the device in accordance with the present invention provided with modified channel for sorting the microparticles by their size or density.
Figure 6b shows bottom view of the device 200 shown in Figure 6a. The water based fluid 208 containing particles of different sizes and densities (e.g. white particles 212 and red particles 214) in the channel having inlet 202, central outlet 204 and side outlets 205. In addition, fixture holes 220 are also provided for fixing the device on the device holder 210 (not shown). This device 200 enables a continuous sorting of different sizes or densities of particles 212, 214, such that a high-concentration of the particles is obtained at central outlet 204 and side outlets 205 carry the remaining base liquid. In this configuration, central outlet 204 extracts large sized (or higher density) particles and side outlets 205 extract the small sized (or lower density) particles.
Figure 7a shows the complete set-up of the second configuration of the device in accordance with the present invention and provided with a modified setup for sorting the microparticles by their size or density. It includes the open channel 200, an electromagnetic vibrator 210, a channel holder 220 with an inlet 202, a central outlet 204 and side outlets 205, a syringe pump 130 and a connector block 240.
Figure 7b shows an enlarged view of the device 200 for sorting the microparticles depicted in Figure 7a. It includes inlet 202, central outlet 204, side outlets 205 as well as particles 212 (white), 214 (red) of different sizes or densities suspended in the water based fluid 208. The device 200 is mounted on a device holder 220 and vibrated by means of electromagnetic vibrator 210. Accordingly, device 100 or 200 described with reference to Figures 6 and 7 above can be used in accordance with the present invention for continuous high-volume concentration (focusing) and/or for continuous high-volume sorting according to the diameter or density of the different particles and/or for continuous extraction of the smaller size or density of particles from a sample of different sized microparticles distributions.

Figure 8 shows the dimensions of device 100, 200 in accordance with the present invention. The device has a length L1+L2 and width W1, whereas the liquid channel 108, 208 has a length L3 and Width W2. The heights of inlet chamber and depth of the outlet chambers are h1 and h2 respectively. In an exemplary embodiment, the open channel has a length of 30 mm (x-plane), width 8 mm (y-plane) and depth 0.2 mm (z-plane).
Figure 9a shows the sorting device 200, in which 1 urn polystyrene (red) particles 214 and 5 μm silica (white) particles 212 are continuously introduced in the channel. The silica particles 212 start moving towards the center 206 of the chamber (along x), while the smaller polystyrene (red) particles 214 keep swirling (in the x-z plane) due to streaming. Both the particles are simultaneously translated in the y direction, through the external flow which continuously introduces fresh particles in the channel. As both these particles 212, 214 approach the side outlets 205, the silica particles 212 (now moving in the center 206 of the channel, parallel to the flow) remain unaffected because of equal and opposite drag force from the side outlets 205, while most of the polystyrene particles 214 tend to follow the streamlines and into the side outlets 205. Further downstream, the silica particles 212 continue moving along y in the straight line S-S and are collected in central outlet 204 along with a few polystyrene particles 214.
Figure 9b shows the first order periodic velocity field in the z direction (surface plot) and steady streaming field (arrow plot) in the chamber in the x-z plane. Here, the actuation of the water 208 filled chamber generates capillary waves at the water-air interface, creating a periodic first order velocity field (depicted by the surface plot depicted. This periodic field is accompanied by steady second order vortices, termed as the streaming field depicted by the arrow plot
Figure 9c shows the simulated movement of the particles in the x-z plane. The first order field causes the accumulation of larger particles PL (over multiple cycles) underneath the capillary wave node (motion depicted by the white line S-S, whilst the smaller particles Ps are dragged away from the collection locations, into the bulk, by the streaming field F (motion depicted by red line.

Figure 10a shows the particle size distribution results after sorting of Silica (white) particles 212 (density = 2000 kg/m3, particle diameter 5 μm) and Polystyrene (red) particles 214 (density = 1050 kg/m3, particle diameter 1 μm) carried out at a tested flow-rate of 600 μl/min. The relative concentrations obtained at the side outlet 205 in the sorting-cum-extraction device in accordance with the present invention are depicted by bar-chart. The side outlets 205 yield a pure sample containing smaller polystyrene particles 214. The relative particle distribution remains same for a flow rate of 100μl/min also.
Figure 10b shows the particle size distribution results after sorting of Silica (white) particles 212 (density = 2000 kg/m3, particle diameter 5 μm) and Polystyrene (red) particles 214 (density = 1050 kg/m3, particle diameter 1μm) carried out at a tested flow-rate of 600 μl/min. The relative concentrations obtained at the central outlet 204 in the sorting-cum-extraction device 200 in accordance with the present invention are depicted by bar-chart. The central outlet 204 yields both smaller polystyrene particles 214 and larger silica particles 212. The central outlet 204 contains about 15% of silica particles.
Figure 10c shows the particle size distribution results after sorting of Silica (white) particles 212 (density = 2000 kg/m3, particle diameter 5 μm) and Polystyrene (red) particles 214 (density = 1050 kg/m3, particle diameter 1 urn) carried out at a tested flow-rate of 100 μl/min. The relative concentrations obtained at the central outlet 204 in the sorting-cum-extraction device 200 in accordance with the present invention are depicted by bar-chart. The central outlet 204 yields both smaller polystyrene particles 214 and larger silica particles 212. The central outlet contains about 85% of silica particles.
The above graphical data shows that at a flow rate of 600 nl/min, the device works primarily as a small-size-particle extraction unit, where a pure sample of polystyrene particles is extracted from the side outlets. Although the sample at the central outlet contains both sets of particles, it can be further refined by multiple passes through the same device. The channel material is not restricted to PDMS only. It can also be configured from glass, metal, plastic, can even be 3D,printed.

Further, as the flow rate decreases, the sorting efficiency of the device increases and results in an 85% sorting efficiency at 100 μl/min. Again, a pure polystyrene particle sample is obtained at the side outlets.
Moreover, it is to be noted that the flow rates at both the central and side outlets is adjusted to be equal at 300 μl/min and 50 μl/min, respectively. The inlet need not necessarily be aligned longitudinally. It can also be placed laterally, or, even the particles can be inserted directly into the channel from a hole at the base.
It is also important to mention that the above flow rates and the corresponding results are applicable to this set of particles only. For different particle sets, the flow rates and corresponding device sorting efficiencies will be different.
Figure 11 demonstrates the particle size distribution results for the size based extraction device for two sets of particles at different excitation amplitudes at side outlets. The particle distribution range in the source samples for both the particles is from 1 nm to 10 μm. Is shows the control of particle distribution from the side outlets of the device while functioning as a particle extraction unit. The particle distribution is controlled by altering the actuation amplitude. As the actuation amplitude is lowered the cut-off values are lowered, hence, particles with lower sizes can be collected. Therefore, in a given particle distribution, it is expected that as the actuation amplitude is decreased, the particles extracted from the side outlets will comprise of smaller particles. It is re-iterated here that the side outlets extract particles which continue to swirl in the streaming flows.
Figure 11a demonstrates the particle distribution of gelatin coated copper particles extracted from the side outlets at different actuation amplitudes (values in the legend). The shift in the distribution peak towards the smaller particle sizes as the amplitude is lowered is clearly visible.
Figure 11b demonstrates the particle distribution of CTAB coated copper particles extracted from the side outlets at different actuation amplitudes (values in the legend). The shift in the distribution peak towards the smaller particle sizes as the amplitude is lowered is clearly visible.

In all the figures of these embodiments Figure 12a to 12h discussed below, the blank rectangular box represents a central outlet for large particles;
cross-hatched box represents a side outlet for smaller particles (for
sorting/extraction device) or pure liquid (for focusing device); and arrow indicates the inlet to the open channel.
Figure 12a shows a second exemplary embodiment 200 of the open channel configurable in accordance with the present invention (already discussed earlier).
Figure 12b shows a third exemplary embodiment 300 of the open channel configurable in accordance with the present invention, wherein the central outlet 204 (the one extracting the larger particles 212) can be at any position along the channel length; however this affects the sorting efficiency. Here, a capillary wave CW1 of one wavelength is formed at the water-air interface. In this case, only one line is formed in the channel.
Figure 12c shows a fourth exemplary embodiment 400 of the open channel configurable in accordance with the present invention, wherein multiple waves are formed at the liquid-air interface, e.g. at higher frequencies, so the number of lines formed in the channel equals the number of waves at the interface (underneath the alternate displacement node positions of the wave). Accordingly, this embodiment demonstrates the presence of two capillary waves CW2 at the interface. It is to be mentioned here that the condition that the particles collect underneath the alternated nodes only is valid for large particles. As the particle sizes decrease, particle collection is observed underneath all the capillary wave nodes. The design of the outlets is modified accordingly, i.e., the central outlet blocks will then be placed underneath all the nodes, with the ide outlet blocks placed in between them.
Figure 12d shows a fifth exemplary embodiment 500 of the open channel configurable in accordance with the present invention. Here, the connection of multiple channels 510, 520, 530 disposed in parallel are vibrated at the same (or different) frequencies and amplitudes for high volume separation. It

is to be mentioned here that operating at different frequencies may imply that the chambers may have different dimensions.
Figure 12e shows a sixth exemplary embodiment 600 of the open channel configurable in accordance with the present invention. Multiple channels, e.g. two channels 610, 620 here, are connected in series and vibrated at different (or same) frequencies and amplitudes for sample refinement or for multiple particle sorting. Each such channel is used to sort at least two particles at a time. So, at least two particles are sorted ant outputted through the central outlet 614 and side outlet 615 respectively of the first channel 610. The output of the central outlet 614 of the first channel 610 is inputted by means of a pump P to the input 622 of the second channel 620 for further sorting of the remaining particles and at least two more particles are sorted through central outlet 624 and side outlets 625 respectively of second channel 620. It is to be mentioned here that operating at different frequencies may also imply that the chambers have different dimensions.
Figure 12f shows a seventh exemplary embodiment 700 of the open channel configurable in accordance with the present invention, wherein the outlets 704, 705 are modified by configuring the central outlet 704 for larger particles and side outlets 705 for smaller particles. The inlet 702 remains the same, as described in earlier cases.
Figure 12g shows an eighth exemplary embodiment 800 of the open channel configurable in accordance with the present invention, wherein the outlets 804, 805 are further modified. Accordingly, particles are extracted from the sides LS and BS of the chambers rather than the chamber floor as in earlier embodiments. This configuration produces high concentration particle separation/concentration/sorting with higher efficiency.
Figure 12h shows a ninth exemplary embodiment 900 of the open channel configurable in accordance with the present invention. The chamber base 907 at the downstream end of the channel 900 is slightly elevated than the chamber base 903 near the inlet 903, forming a small barrier for the particles

collected in lines. The smaller particles keep circulating due to the streaming fields and are dragged downstream to the outlet 905 at the channel end. The particles that are restricted by the barrier either drop down into the central outlet 904 or a low flow velocity extracts these particles.
Figure 12i shows a tenth exemplary embodiment 1000 of the open channel configurable in accordance with the present invention, wherein the channel near the outlets is enclosed. The part of the channel where the particles are focused is open while the rest of the channel downstream is enclosed. After focusing, the laminar flow causes the particles to continue in their path and to get collected / separated at the respective outlets. This design reduces the amount of evaporation from the channel. The same enclosed configuration can be used for other outlet configurations discussed above.
Figure 13a to 13c show, as an example, the steps involved in fabrication of a PDMS channel using molding.
Figure 13a shows the mold which can be made from a cut-out from scotch tape/paper or 3D printed or machined using traditional processes such as milling, shaping. This serves as the negative for creating the open channel.
Figure 13b shows the mold stuck to the base of a tank. After this, PDMS is poured in the tank and, subsequently, is heat treated at 80°C for a couple of hours until solidification
Figure 13c shows the resulting, solidified, PDMS channel after removal from the tank. The figure also depicts, as an example, the addition of two separate PDMS blocks which serve as the flow inlet and outlet to the channel; these additional blocks are bonded to the PDMS channel. In other variants, the inlet and outlets can be fabricated with the channel mold itself, or holes can be punched, at the desired locations, where tubings can be connected.
A few additional points to be noted regarding the channel designs:

1. The number of side outlets are not restricted to two. There can be multiple outlets on either side of the center of the channel. The only condition is that the placement of the side outlets should be symmetric.
2. The inlet need not necessarily be placed at the center of the channel. The particles can enter the channel from the sides, and also from the floor of the channel as well.
3. In the embodiments a-f, the tubing from the outlets can be placed either on top of the device (as shown in Figure 5 (c)), or at the floor of the channel as shown in Figure 8 (a). A similar configuration can be arranged for the inlet also.
DESCRIPTION OF THE PRESENT INVENTION
Basically, the device in accordance with the present invention consists of (a) particle focusing unit and (b) particle sorting-cum-small size particle extraction unit. As discussed earlier, the device 100, 200 is mounted on a device holder and vibrated by means of an electromagnetic vibrator or shaker 110, 210 using an input signal through an AC signal generator (not shown).
As an example of the device operation, the following discussion pertains to a specific case, where the PDMS channel has a length of 30 mm (x-plane), width 8 mm (y-plane) and depth 0.2 mm (z-plane). In all the following examples, the channel is vibrated at a frequency of 13 Hz to actuate a resonance capillary wave on one wavelength at the water-air interface. The device dimensions and actuation frequency can be varied after necessary considerations.
(a) Particle focusing unit: The focusing mechanism is based on the principle that the vibrating capillary wave at the water-air interface creates a periodic first order velocity field, which causes the accumulation of particles underneath the capillary wave node that corresponds to the center of the channel 108, 208. As an example,

silica particles having 5 urn diameter and density of 2000 kg/m3 have been used in base liquid water.
• The amplitude here is maintained at approximately 200 urn, but it can be altered, where the maximum amplitude is determined by the limit, so that the particles do not swirl in the streaming flows.
• The lowest amplitude is determined by whether the particles are getting focused before reaching the outlet 104, 204, 205.
• The maximum flow rate obtained in this device was approximately 1800 ul/min, which is determined by whether the particles are getting focused before reaching the outlet 104, 204, 205. The width of the focused sample is about 5-10% of the channel width. This value of the focused width depends on the vibration amplitude.
The main parameters governing the particle focusing operation are as under:
1. Particle size,
2. Particle density,
3. Flow rate,
4. Vibration amplitude,
5. Particle concentration, and
6. Channel dimensions.
However, it should be noted that the effect of the above-listed parameters on the focusing efficiency of the device is not mutually exclusive. For instance, at critical limits, an increase in the flow rate will require a longer channel length or higher vibration amplitude to ensure an efficient focusing of the particles.
(b) Particle sorting-cum-small size particle extraction device:The dimensions of the complete PDMS block are shown in Figure 8. The main channel in the device, where fluid is inserted and particle collection occurs has the following dimensions: Length (L3) = 30 mm (y-plane), Width (W2) = 8 mm (x-pjane) and depth (h) = 0.2 mm (z-plane).

As already mentioned the device is mounted on a holder and vibrated, in the x direction through an electromagnetic vibrator or shaker 210, as shown in Figure 7a. The vibrator 210 is given an input signal through an AC signal generator.
(i) The device is vibrated at a frequency of 13 Hz to actuate a capillary wave of one wavelength at the water- air interface; the resulting 2D displacement wave-field is depicted in Figure 9b.
(ii) The particles considered for sorting are 1 urn polystyrene (density= 1500 kg/m3) and 5 urn silica particles (density= 2000 kg/m3).
(iii) The amplitude is altered depending on the particle sizes to be sorted, as determined by their cut-off characteristics. For the present case, the voltage supplied to the vibrator is approximately 0.5 V (amplitude approximately 200 urn). For proper device functioning, the smaller/lighter polystyrene particles remain swirling in the liquid bulk and therefore should be obtained at the side outlets 205, while the larger/heavier silica particles collect at the center of the channel and are obtained at the outlet 204.
(iv) Apart from the vibration amplitude, the sorting efficiency can be altered depending on the flow rate. For instance, at a flow rate of 600 ul/min about 15% of silica particles are obtained at the outlet 204 (Figure 10b), while at 100 ul/min flow rate, about 85% of silica particle are obtained at the outlet 204 (Figure 10c). In both cases, only polystyrene particles are obtained at the side outlets 205 (Figure 10a). The flow rates at the side and central outlets are same. The difference between these flow rates also determines the sorting efficiency.
(v)The particle extraction device also works on the same principle of modifying the cut-off characteristics of the system to extract a particle sample of the desired size. Here, the cut-off characteristics are altered by changing the vibration amplitude, for given chamber dimensions and particle size/density. As an example, copper particles (with surfactant molecules attached to its surface) of a broad size distribution, 1 nm to 1

|jm are inserted in the channel at the inlet 202. By altering the vibration amplitude, particles of a narrower size distribution can be extracted from the outlet 205. As the vibration amplitude is increased, more number of larger particles are dragged into the streaming flows and are therefore extracted from the outlet 205, as seen in Figure 11a and Figure 11b for copper particles coated with gelatin and CTAB, respectively.
The parameters governing the sorting efficiency are as under:
1. Relative particle-sizes,
2. Relative particle-density,
3. Flow rate,
4. Vibration amplitude,
5. Particle concentration,
6. Channel dimensions, and
7. Relative flow rates at the outlet.
It is to be mentioned here that the effect of the above listed parameters on the device's sorting efficiency is not mutually exclusive. For instance, an increase in the particle concentrations reduces the sorting efficiency for the same flow rate and vibration amplitude.
WORKING OF THE INVENTION
Process control is achieved by means of the parameters which control the respective desired function. A necessary condition for the particles which can be manipulated using the idea underlying this invention is that the particles should sediment weakly for the particle collection to occur. For instance, highly stable colloidal suspensions will be immune to this particle collection and will keep swirling. The process disclosed according to the present invention involves the following process steps:
(A) Particle focusing: The following process control parameters are identified based on a given particle size and density which needs to be focused.

a) Particle properties: Particles with higher size (or density) collect faster as
compared to smaller sized particles. Therefore, under the conditions that
the particles are unaffected by the streaming fields, the focusing of smaller
particle sizes (or densities) individually requires:
(i) higher vibration amplitudes,
(ii) lower flow rates,
(iii) larger channel lengths,
(iv) higher operating frequencies (or smaller channel widths).
It should be noted here that the above parameters are interdependent. Therefore, the abovementioned dependencies for higher particle size are subject to the condition that the remaining parameters remain unchanged. It should be noted further that even though an increase in the operating frequency and vibration amplitude leads to higher particle collection forces, the particles become more prone to be affected by the streaming fields and therefore, might not collect at the center of the channel.
b) Channel dimensions:
(I) Channel width (in x direction) is determined by the particle size/ density that is to be focused. The channel width should be such that the particles do not get trapped in the streaming flows, which would hinder the focusing of particles. A smaller particle size (or density) will require a wider channel. It should be noted that larger channel widths are desirable for handling higher flow rates. Moreover, it enables focusing in a single device, a large range of particle sizes.
Fixing, the channel width and depth also automatically fixes the operating frequency, for a wave of one wavelength.
Theoretically, frequency is given as:


ω = frequency
λ = wavelength,
p = density of the liquid,
γ = surface tension,
g - acceleration due to gravity, and
h = channel depth.
The experimental frequencies alter slightly from this expression.
(II) Channel depth (in z direction) has no restriction in terms of the minimum channel depth. The maximum channel depth should be less than the capillary wavelength.
(III) Provided that other parameters are fixed, a larger channel length (in y direction) is required for:

• smaller channel width, and
• higher flow rates.
• lower vibration amplitudes.
c) Vibration amplitude:
Provided that other parameters are fixed, higher vibration amplitude is
required for:
(i) higher flow rates
(ii) smaller channel lengths
Again, the vibration amplitudes affect the cut-off characteristics; therefore, an increase in the actuation amplitude should not cause the particles to swirl in the liquid bulk.
d) Flow rate:
Provided that other parameters are fixed, a higher flow rate necessitates: (i) higher vibration amplitudes (ii) larger channel lengths.
There is no limit to the minimum flow rate.

It is to be mentioned here that the maximum concentration of the particles should not exceed approximately 10% (experimental observations). Higher concentrations cause incomplete focusing, thereby, hampering the focusing efficiency; this implies that some particles enter the side outlets 205.
(B) Particle sorting + small size particle extraction: The following process control parameters are identified based on the given particle sizes and densities which needs to be sorted OR the given size distribution from which the smaller/lighter particles need to be extracted.
(a) Channel dimensions: As with the previous case (A), the particle sizes determine the channel width and depth. The channel length is determined by the larger/heavier particles focusing ability. Therefore, the same rules apply here again as for the above mentioned case (A). So in this case also, the larger particles should be focused before reaching the side outlets.
(b) Vibration amplitude: The vibration amplitude is fixed and is determined by the consideration that the smaller/lighter particles should swirl while the larger/heavier particles should focus. In case of the particle extraction, changes in the vibration amplitude will change with particle distribution of the extracted sample: higher amplitudes will cause a larger/heavier particle size range to be extracted from the original sample.
(c) Flow rate: The flow rate considerations are same as in the previous case (A), which assures that the larger particles are focused at the channel center before they reach the side outlets.
(d) Particle concentration: Higher particle concentrations compromise the efficiency of the sorting device, as more number of smaller sized particles will be obtained at the central outlet. However, the side outlets can remain devoid of the larger particles. As a result of this, the particle extraction device operation is immune to concentration effects.

It is to be mentioned here that the maximum total concentrations of the particles should not exceed approximately 10% (experimental observations). Higher concentrations cause incomplete focusing, thereby, hamper the sorting/extraction efficiency.
(e) Relative flow rates at the outlet: Higher flow rate at the side outlets will ensure a larger number of smaller particles getting extracted, thereby increasing the sorting/extraction efficiency.
The sorting device here can sort two different particles at a time. However, by connecting multiple such devices in series, multiple particle types can be sorted (Figure 11e).
C) Focusing device:
(i) The device has been validated for metal/polymer particle sizes from
100 nm to 100 urn, (ii) Channel widths (from 1 mm to 10 mm) and lengths (from 5 mm to 100
mm) have been validated, and (iii) Flow rates up to 2000 ul/min have been tested.
COMMERCIAL APPLICATIONS OF THE TECHNOLOGY/INVENTION
(a) Particle focusing through this device offers a method for high throughput extraction of a clear base liquid from a given particle suspension, e.g., cleaning water from sediment particulate matter. In other words, separation of particles from the base liquid.
(b) Microparticle synthesis processes produce particle sizes in a wide size range. A reduction in the particle size distribution of the sample involves further processing which adds to the manufacturing cost. Such samples are required for applications in coatings, drug delivery etc. The present invention provides a low cost, high throughput alternative to extract particles in a smaller size range from a sample. Further, the amplitude dependency of this process provides an easy control over the particle size distribution and therefore, a highly tunable operation. The device can be used for polymeric and metal micro- and nano- particles.

(c) The density dependency of the particles allows for a simpler handling of metal nanoparticles (in the 100 nm range). Such particles are often required in producing high surface finish coatings and in bio- particle applications as target materials for differentiation.
(d) The method can also be used to separate bio-particles from the synthetic particles.
(e) Microparticles are also utilized as beads which can be functionalized to attach bio-particles, which can be further used to separate such bio-particles from a solution. Further, different bio-particles can also be sorted/separated by attaching to differently sized bio-functionalized beads.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The device to control particle focusing, sorting, extraction and collection in a continuously flowing system and method therefor in accordance with the present invention have the following advantages over existing active particle sorting/focusing techniques (optical, acoustic, magnetic, inertial, di-electrophoretic):
1. High throughput: Tested flow rates for the above mentioned device (and particles) reach up to 600 ul/min of sample inflow. The setups can achieve flow rates up to 10000 ul/min.
2. Sample concentration: The current setup was tested at a sample concentration of 10% by volume for both the particles, which is comparable to other flow based techniques.
3. Particle range: The above device can handle particles ranging from 10nm to over 1000pm (without altering the dimensions). However, it is to be mentioned here that the above three parameters are not mutually exclusive in determining the sorting/focusing efficiency.
4. Simple experimental setup and ease of operation: The actuation mechanism requires an electromagnetic vibrator/shaker vihratinq at low

frequencies (within 100 Hz) actuated by a signal generator. The peak to peak operating voltages are within 2 V. The corresponding displacement amplitude is within 1000 urn, depending on the particle size and density. The simple device fabrication and the ease of mounting the device further ease the device operation.
5. Simple device fabrication: The open channel devices can be 3D printed, manufactured from metals/polymers using conventional fabrication techniques or made from polymers such as PDMS using simple molds (scotch tape was used as a mould in the present devices).
6. Low energy requirements: Due to low operating voltages, the amount of energy required is low.
7. No heating: Samples do not demonstrate any heat build-up for long operation times.
8. Scale up: System scale up is feasible, by mounting multiple channels in parallel (or series) on a single (or multiple) shaker.
9. Low cost: The simple experimental setup and low power requirements drastically reduce the fabrication and operation cost compared to methods like optical, electric and acoustic.
10. Particle damage: Particle damage during operation is very low due to low
shear forces acting on the particle in this flow field.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.
Although, only the preferred embodiments have been described herein, the skilled person in the art would readily recognize to apply these embodiments with any modification possible within the spirit and scope of the present invention as described in this specification.
Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.
The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. A device for controlling particle collection in a continuously flowing multi-
particle water-based liquid-particle suspension system, the device
comprises:
- at least one vibrating chamber including at least one open channel
having at least one inlet disposed at one longitudinal end, or laterally at one end, or at the floor of the open channel at one end thereof and a plurality of outlets disposed at or adjacent the other longitudinal end thereof;
- at least one holder for holding the vibrating chamber;
- at least one EM (electromagnetic) vibrator or a crank-shaft connected motor, for vibrating the chamber;
- at least one pump for maintaining a continuous flow of the liquid-particles suspension in the open channel;
wherein the chamber is vibrated in a direction transverse to the flow of the liquid-particle suspension continuously introduced in the open channel in through the inlet and the large particles are extracted from at least one central outlet and the remaining based liquid and/or particles are extracted through the side outlet/s.
2. Device as claimed in claim 1, wherein one outlet is provided central at the end opposite the inlet end of the open channel and at least one pair of side outlets are provided adjacent the central outlet.
3. Device as claimed in claim 1, wherein the central outlet is provided at any position along the length of the open channel, preferably towards the longitudinal end away from the inlet end of the open channel and at least one pair of side outlets is provided and wherein the central outlet and side outlets both are uniformly disposed about the same longitudinal cross-section of the open channel.

4. Device as claimed in claim 1, wherein at least one pair of central outlets and at least three side outlets are configured at any position along the length of the open channel, preferably towards the longitudinal end away from the inlet end of the open channel and the outlets being uniformly disposed about a predetermined longitudinal cross-section of the open channel.
5. Device as claimed in claims 1 and 4, wherein a plurality of open channels are disposed in parallel along the longitudinal direction thereof and connected to a common inlet, the open channels being vibrated at the same frequency and amplitude for high-volume separation of particles.
6. Device as claimed in claim 5, wherein the plurality of open channels is vibrated at different frequencies and/or amplitudes for high-volume separation of particles.
7. Device as claimed in claims 1 and 2, wherein a plurality of open channels is disposed in series and vibrated at same and/or different frequencies and/or amplitudes for sample refinement or multiple particle sorting; the first open channel is connected to a main inlet and the outlet of the first open channel is connected to the inlet of the second open channel via a pump.
8. Device as claimed in claim 1, wherein at least one central outlet is provided at the longitudinal end disposed opposite the inlet end and one side outlet each is uniformly disposed about the central outlet at the same end; the central outlet for extracting larger particles and side outlets for extracting smaller particles.
9. Device as claimed in claim 1, wherein the inlet is configured in the top, side or bottom and the outlets are configured in the floor of the open channel.
10. Device as claimed in claim 1, wherein the inlet is configured in the top of the open channel and the outlets are configured in the sides of the open channel.

11. Device as claimed in claim 10, wherein the open channel is configured with a plurality of floor levels; the inlet end floor level disposed at a lower level than the floor/s at the other longitudinal end of the open channel restricting the flow of heavier particles by means of subsequently disposed stepped floor/s; and wherein a central outlet is provided adjacent the lower floor level of the inlet end floor for extracting restricting the flow of heavier particles; and at least one outlet is configured in each subsequent higher level floor of the open channel for extracting smaller particles.
12. Device as claimed in anyone of the claims 1 to 11, wherein the open channel is configured with the following dimensions:

(a) Length in a range of 5 to 100 mm, preferably 20 to 40 mm, more preferably 30 mm;
(b) Width in a range of 1 to 20 mm, preferably 6 to 8 mm, more preferably 8 mm;
(c) Depth in a range of 0.1 to 10 mm, preferably 0.1 to 1 mm, more preferably 0.2 mm.
13. A method for controlling particle collection in a continuously flowing multi-
particle liquid-particle suspension system by means of the device as
claimed in anyone of the claims 1 to 12, the method comprises the steps of:
- mounting the chamber containing open channel/s on the holder thereof;
- supplying the open channel/s with a multi-particle liquid-particle suspension having particles of at least 0.01 μm and upto 100 urn or more at a flow rate of 50 to 10000 )μl/min, preferably 600 μl/min;
- vibrating the open channel/s at a frequency of 1 to 200 Hz, preferably 12 to 15 Hz, more preferably 13 Hz and with an amplitude of 20 to 1000 μm, preferably 200μm;
- creating a periodic first order velocity field accompanying a streaming field including steady second order vortices

- focusing the larger/heavier particles, preferably over multiple cycles
underneath a capillary wave node by means of the first order velocity field;
- sorting the particles by dragging away the smaller/lighter particles from the collection locations into the bulk of the multi-particle liquid-particle suspension by means of the streaming field; and
- extracting larger/heavier particles from the central outlet and smaller/lighter particles from the side outlets.
- concentrating, focusing particles with different surface chemistries

14. Device as claimed in claim 1 to 12, wherein the open channel is made of Polydimethylsiloxane (PDMS).
15. Device as claimed in claim 1 to 12, wherein the open channel is made of any of the materials including glass, metal, plastic.
16. Device as claimed in claim 1 to 12, 14, 15, wherein the open channel is made by 3-D printing.
17. Method of fabricating a PDMS channel as claimed in claim 4, wherein the method includes the steps of:
(i) fabricating a mold through a cut-out from scotch tape/paper;
(ii) affixing the mold to the base of a rectangular tank for subsequently
pouring PDMS over the mold; (iii) heat treating PDMS filled tank at approximately 80°C for a
predetermined duration until solidification of PDMS; (iv) removing the solidified PDMS carefully from the base to obtain the
desired channel shape; and (v) adding inlets and outlets as punched holes to serve as connections
for the tubing.

18. Method as claimed in claim 17, wherein the mold is fabricated through 3D printing.
19. Method as claimed in claim 17, wherein the mold is fabricated through fabrication processes, such as milling and shaping.
20. Method as claimed in anyone of the claims 17 to 19, wherein inlets and outlets are added by bonding separate PDMS blocks containing holes which serve as connections for the tubing.
21. Method as claimed in anyone of the claims 17 to 19, wherein the holes are incorporated within the mold configuration itself.