Saccharomyces cerevisiae cell directional sorting and gathering chip based on acoustic surface wave driving and control system

Abstract

The invention discloses a yeast cell directional sorting and gathering chip based on surface acoustic wave driving and a control system.The chip comprises a piezoelectric substrate, two interdigital electrode pairs, a micro-fluidic channel and a liquid drop residing circular ring, the first interdigital electrode pair is arranged on the two sides of the micro-fluidic channel and used for exciting a symmetrical standing wave field, and the second interdigital electrode pair is arranged on the two sides of the micro-fluidic channel and used for exciting a liquid drop residing circular ring; separating yeast cells with relatively large particle sizes from small-particle impurities through acoustic radiation force; and the second interdigital electrode pair is arranged on the two sides of the liquid drop residing circular ring, has an offset arrangement structure, and excites vortex acoustic streaming with a rotation characteristic in the liquid drop so as to realize center aggregation of target cells. The chip integrates sorting and gathering functions, has the advantages of no mark, no contact, high treatment efficiency and the like, and is suitable for the fields of biological sorting, environment detection, fermentation engineering and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface acoustic wave, in particular to a yeast cell directional sorting and aggregation chip based on surface acoustic wave driving and a control system. BACKGROUND

[0002] In recent years, microfluidic systems have been widely used in biological engineering fields such as microorganism manipulation and cell screening. In particular, acoustic microfluidic technology, which combines acoustics and microfluidic technology, can realize non-destructive and non-contact sorting and manipulation of particles with different particle sizes, densities or compressibilities by exciting acoustic radiation force (ARF) and acoustic streaming (ASF) in microfluidic channels.

[0003] Yeast cells, as common eukaryotic microorganisms, are widely used in fermentation engineering, metabolic research and environmental microbial analysis. In cell culture or fermentation systems, bacterial contamination, extracellular impurities or other small particles (such as unused carbon source precipitates) often cannot be efficiently separated by traditional methods, affecting subsequent detection and processing results.

[0004] Compared with traditional magnetic bead sorting, filtration centrifugation and other methods, surface acoustic wave (SAW) technology has the advantages of no labeling, mild processing and high controllability, and is particularly suitable for continuous and non-destructive sorting of microorganisms such as yeast cells. At the same time, the acoustic microfluidic structure can also excite a stable vortex flow field in the droplet, and the target cells can be aggregated under the synergistic action of acoustic radiation force and viscous resistance, which is helpful for subsequent image recognition, quantitative analysis and recovery.

[0005] However, there is still a lack of integrated design for efficient sorting and aggregation of yeast cells, which makes it difficult to balance high-throughput processing and spatial aggregation control, limiting its application and promotion in practical scenarios such as automated fermentation control and microbial sample purification. SUMMARY

[0006] In order to solve the above problems existing in the prior art, the present application proposes a yeast cell sorting and aggregation chip based on surface acoustic wave and a control system, so as to realize the central aggregation of target cells, thereby realizing the continuous sorting and stable central aggregation of yeast under the conditions of no labeling and low temperature rise, significantly improving the unit volume concentration and purity, shortening the pretreatment time, reducing secondary mixing and sample loss, facilitating imaging quantification and subsequent fermentation / detection, and having higher universality and consistency than magnetic bead, filtration centrifugation and inertial / DLD / DEP microfluidic schemes.

[0007] In order to achieve the above application purposes, the following technical solutions are adopted in the present application: The yeast cell directional sorting and gathering chip based on surface acoustic wave driving has the characteristics that it comprises a piezoelectric substrate, two interdigital electrode pairs, a microfluidic channel and a droplet residence ring. The piezoelectric substrate is provided with the two interdigital electrode pairs. The microfluidic channel is arranged between the first interdigital electrode pair and comprises three inlets, two outlets and a main channel connecting the inlets and the outlets, wherein the middle inlet is used for injecting a sample flow containing target particles and non-target particles, and the two side inlets are used for injecting sheath flows; the two outlets are respectively a target particle outlet and an impurity / waste liquid outlet. The droplet residence ring is arranged between the second interdigital electrode pair and is in fluid communication with the target particle outlet only.

[0008] The yeast cell directional sorting and gathering chip based on surface acoustic wave driving has the characteristics that it comprises a piezoelectric substrate, two interdigital electrode pairs, a microfluidic channel and a droplet residence ring. The first interdigital electrode pair and the second interdigital electrode pair are both composed of two groups of oppositely arranged interdigital electrodes; each group of interdigital electrodes comprises 25-40 pairs of interlaced electrode fingers; the width of the electrode fingers is w, the gap between adjacent two electrode fingers is g, and w and g are respectively set in the range of 3-150 μm.

[0009] Further, the width w and the gap g satisfy w = g = λ / 4, wherein λ is the wavelength of the surface acoustic wave propagating on the piezoelectric substrate; the driving frequency f of the interdigital electrode and the phase velocity v of the surface acoustic wave satisfy f·λ = v.

[0010] Further, the center line of the main channel of the microfluidic channel passes through the acoustic field action area between the two groups of interdigital electrodes in the first interdigital electrode pair; Taking the center of the droplet residence ring as the origin O, a straight line passing through O and perpendicular to the center line of the main channel of the microfluidic channel as the y-axis, and a straight line passing through O and parallel to the center line of the main channel of the microfluidic channel as the x-axis, a rectangular coordinate system O-xy is established; The two groups of interdigital electrodes in the second interdigital electrode pair are located in the second and fourth quadrants or the first and third quadrants of the rectangular coordinate system O-xy, and the geometric center line L2 of the second interdigital electrode pair passes through the origin O. The edges of the electrode fingers on the side close to the y-axis in the two groups of interdigital electrodes of the second interdigital electrode pair coincide with the y-axis, and the extension direction of the electrode fingers of each group of interdigital electrodes is parallel to the x-axis.

[0011] Further, the materials of the microfluidic channel and the droplet residence ring are both polydimethylsiloxane (PDMS); The thickness of the microfluidic channel is 2-7 mm; The thickness of the droplet residence annulus is 0.1-1mm. The material of the piezoelectric substrate is 128° Y-cut lithium niobate.

[0012] Further, the metal material of the first interdigital electrode pair and the second interdigital electrode pair is selected from one or more of aluminum (Al), gold (Au), chromium (Cr), and titanium (Ti), and preferably, chromium (Cr) or titanium (Ti) is used as an adhesion layer, and aluminum (Al) or gold (Au) is used as a conductive layer; the total thickness of the metal layer is 200-300 nm.

[0013] Further, the microfluidic channel and the droplet residence annulus are bonded to the piezoelectric substrate by oxygen plasma surface activation, and the bonded chip is subjected to post-curing treatment at 65-90 °C for 30-120 minutes to reinforce the bonding of the chip.

[0014] The application also provides a control system for driving the yeast cell directional sorting and aggregation chip driven by the surface acoustic wave, which comprises a radio frequency signal source, a power amplifier, a direct current power supply, a switching unit, a first micro-injection pump, a second micro-injection pump, a sheath flow injector, and a sample injector. The direct current power supply supplies power to the power amplifier. The adjustable radio frequency signal output by the radio frequency signal source is amplified by the power amplifier, and then input to the first interdigital electrode pair by the switching unit in the sorting stage, so as to establish a standing wave acoustic field in the action zone of the microfluidic channel, or input to the second interdigital electrode pair in the aggregation stage, so as to form a unidirectional rotating acoustic flow in the droplet residence annulus. The sheath flow injector is driven by the first micro-injection pump to push the sheath flow to the two side inlets of the microfluidic channel. The sample injector is driven by the second micro-injection pump to push the sample flow to the middle inlet of the microfluidic channel. Under the action of the standing wave acoustic field, the sheath flow laterally constrains the sample flow, so that the sample flow forms a stable narrow band in the middle part of the main channel, so as to sort the particles in the sample flow in the main channel, and the target particles after sorting are output from the target particle outlet of the microfluidic channel and flow into the droplet residence annulus; the non-target particles after sorting flow out from the impurity / waste liquid outlet of the microfluidic channel. The target particles in the droplet residence annulus are centrally aggregated under the action of the unidirectional rotating acoustic flow.

[0015] Further, the driving frequency f1 of the radio frequency signal source in the sorting stage is between 5-340 MHz, and the output power is between 20-33 dBm; the flow ratio between the sample flow and the sheath flow is (0.5-1):(2-10). The driving frequency f2 of the radio frequency signal source in the aggregation stage is f1 or satisfies 0.9*f1<=f2<=1.1*f1.

[0016] Compared with the prior art, the application has the beneficial effects that: 1. The application integrates the microfluidic channel with three inlets and double outlets and the droplet residence ring on the piezoelectric substrate, and only the target particle outlet is in fluid communication with the ring, so that the closed loop of "sorting, introduction and aggregation" is completed in the same chip, and the problems of multiple transfers, secondary mixing and large sample loss in offline processes such as magnetic beads, filtration and centrifugation are overcome; in combination with the time sequence of "sorting stage, aggregation stage and shutdown recovery" in the control method, the pre-treatment link is shortened, the error source is reduced, and the consistency is improved.

[0017] 2. The application uses a surface acoustic wave (SAW) standing wave field to realize non-marking and non-contact sorting in the sorting section: the first interdigital electrode pair is designed to be driven at w=g=λ / 4, and after three-inlet sheath flow focusing, differential acoustic radiation force is applied to particles of different particle sizes / acoustic properties, so as to separate at the double-outlet, overcoming the problems of magnetic beads relying on marking, DEP being sensitive to medium, and high shear and activity damage in centrifugation / filtration; thereby achieving the effects of improving purity and recovery rate, and better maintaining cell activity and phenotype.

[0018] 3. In the aggregation section, the second interdigital electrode pair is geometrically aligned with the ring: taking the center O and the y-axis as the reference, the electrode pair is in the diagonal quadrant and the geometric center line L2 passes through O, and the edge of the electrode finger on the side close to the y-axis is coincided with the y-axis, and the extension direction of the electrode finger is parallel to the x-axis; under the layout and driving, a stable vortex acoustic flow is formed in the ring, overcoming the problems of position drift in aggregation and difficulty in fixing the sampling site in microscale in traditional methods and most sorting structures, so as to realize the effects of reproducible central aggregation, convenient imaging counting and small volume recovery.

[0019] 4. The application adopts a three-inlet design of intermediate sampling and two-side sheath flow, and independently discharges non-target / waste liquid without communicating with the ring, solving the problems of wall pollution, pore blockage, impurity backflow and the like in traditional filtration and microstructure dense schemes; in actual operation, the sorting boundary can be stably controlled through flow ratio, and small fluctuations in purity and aggregation indicators and channel cleanliness can still be maintained under long-term continuous operation, thereby reducing maintenance cost and improving long-term stability.

[0020] 5. In terms of materials and processes, this invention adopts a metallization stack of PDMS microfluidic layer + 128° Y-cut lithium niobate substrate and Cr / Ti adhesion layer + Al / Au conductive layer, and completes the sealing by oxygen plasma activation followed by bonding and curing. This solves the comprehensive trade-off between device sealing reliability, corrosion resistance and energy conversion efficiency. This results in low temperature rise, low power consumption and improved repeated service life, and ensures stable performance in different media such as PBS or diluted fermentation broth, and is easy to scale up. Attached Figure Description

[0021] Figure 1 This is a top view schematic diagram of the chip of the present invention; Figure 2 This is a schematic diagram of the microfluidic channel structure of the present invention; Figure 3 This is a schematic diagram of a single interdigital electrode structure of the present invention; Figure 4 This is a schematic diagram of the sorting mechanism and sheath flow of the present invention; Figure 5 This is a schematic diagram of the droplet-residing ring and its corresponding interdigitated electrode distribution structure of the present invention; Figure 6 This is a schematic diagram of the aggregation mechanism of the present invention; Figure 7 This is a flowchart illustrating the overall operation of the control method and system of the present invention. Figure 8 This is a schematic diagram of the cross-section of the structure of the present invention; Figure 9 This is a flowchart of the manufacturing process of the present invention; Figure 10 This is a diagram showing the sorting experiment results of the present invention; Figure 11 This is a diagram showing the aggregation experiment results of this invention.

[0022] Labels in the figure: 1. Piezoelectric substrate; 21. First interdigital electrode pair; 22. Second interdigital electrode pair; 3. Microfluidic channel; 4. Droplet-residing ring; 501. Radio frequency signal source; 502. Power amplifier; 503. DC power supply; 506. First micro-injection pump; 507. Second micro-injection pump; 508. Sheath flow injector; 509. Sample injector. Detailed Implementation

[0023] In this embodiment, a yeast cell directional sorting and aggregation chip driven by surface acoustic waves is described, such as... Figure 1 As shown, it includes a piezoelectric substrate 1, a first interdigital electrode pair 21, a second interdigital electrode pair 22, a microfluidic channel 3, and a droplet-residing ring 4.

[0024] A microfluidic channel 3 is arranged between the first interdigital electrode pair 21, which consists of three inlets, two outlets and a main channel connecting the inlets and the outlets, wherein the middle inlet is used for injecting a sample flow containing target particles and non-target particles, the two side inlets are used for injecting sheath flows, and the two outlets are respectively a target particle outlet and an impurity / waste liquid outlet; A droplet residence ring 4 is arranged between the second interdigital electrode pair 22, and only the target particle outlet is in fluid communication with the droplet residence ring 4, so that the "sorting → introduction → aggregation" is realized in a closed loop in the same chip. Figure 2 The three-inlet / two-outlet and the main channel direction and naming are shown, Figure 5 The communication relationship of the target particle outlet to the droplet residence ring 4 is shown.

[0025] The first interdigital electrode pair 21 and the second interdigital electrode pair 22 are both composed of two groups of interdigital electrodes arranged oppositely, as shown in Figure 3 Each group of interdigital electrodes includes 25-40 pairs of interlaced electrode fingers; the finger width of the electrode fingers is w, and the finger gap between the adjacent two electrode fingers is g, which are respectively set in the range of 3-150 μm. Preferably, w=g=λ / 4, wherein λ is the wavelength of the surface acoustic wave propagating on the piezoelectric substrate; the driving frequency f of the interdigital electrode and the phase velocity v of the surface acoustic wave satisfy f·λ=v.

[0026] As shown in Figure 4 The center line of the main channel of the microfluidic channel 3 passes through the acoustic field action area between the two groups of interdigital electrodes of the first interdigital electrode pair 21, so as to ensure the effective coupling of the acoustic field and the fluid field in the sorting section.

[0027] In the aggregation section, the center of the droplet residence ring 4 is taken as the origin O, a straight line passing through O and perpendicular to the main channel of the microfluidic channel 3 is taken as the y-axis, and a straight line passing through O and parallel to the main channel is taken as the x-axis, so as to establish a rectangular coordinate system x-y with O as the origin; as shown in Figure 5 The second interdigital electrode pair 22 is located in the second quadrant and the fourth quadrant or the first quadrant and the third quadrant of the rectangular coordinate system, and the geometric center line L2 thereof passes through the origin O; the edges of the electrode fingers on the side close to the y-axis in the two groups of interdigital electrodes coincide with the y-axis, and the extension direction of the electrode fingers is parallel to the x-axis.

[0028] As shown in Figure 6 In the position and direction relationship shown in Figure 5 Under the position and direction relationship shown in

[0029] As shown in Figure 8The structural cross-section and material layers shown are as follows: the microfluidic channel 3 and the droplet-retaining ring 4 are made of polydimethylsiloxane (PDMS), the thickness of the microfluidic channel 3 is 2–7 mm, and the thickness of the droplet-retaining ring 4 is 0.1–1 mm; the piezoelectric substrate 1 is made of 128° Y-cut lithium niobate.

[0030] The metal materials of the first interdigital electrode pair 21 and the second interdigital electrode pair 22 are selected from one or more of aluminum (Al), gold (Au), chromium (Cr), and titanium (Ti). Preferably, chromium (Cr) or titanium (Ti) is used as the adhesion layer and aluminum (Al) or gold (Au) is used as the conductive layer. The total thickness of the metal layer is 200-300 nm.

[0031] The microfluidic channel 3 and the droplet-residing ring 4 are bonded to the piezoelectric substrate 1 after oxygen plasma surface activation. Following bonding, the entire chip is post-cured at 65–90°C for 30–120 minutes to achieve stable sealing and acoustic coupling performance. Figure 9 As shown, the complete chip manufacturing process includes metallization, PDMS mold replication, surface activation, bonding, and post-curing.

[0032] The control system for driving the above-mentioned chip includes an RF signal source 501, a power amplifier 502, a DC power supply 503, a first micro-injection pump 506, a second micro-injection pump 507, a sheath flow injector 508, and a sample injector 509.

[0033] like Figure 7 As shown, DC power supply 503 supplies power to power amplifier 502; After the adjustable radio frequency signal output by the radio frequency signal source 501 is amplified, the amplified adjustable radio frequency signal is input to the first interdigital electrode pair 21 through the switching unit 504 during the sorting stage, thereby establishing a standing wave sound field in the action area of ​​the microfluidic channel 3, or inputting the amplified adjustable radio frequency signal to the second interdigital electrode pair 22 during the aggregation stage, thereby forming a unidirectional rotating acoustic flow in the droplet residence ring 4. The first micro-injection pump 506 drives the sheath flow injector 508 to push the sheath flow to both inlets of the microfluidic channel 3; The second micro-injection pump 507 drives the sample injector 509 to push the sample flow into the middle inlet of the microfluidic channel 3 to form a preset flow ratio between the sample flow and the sheath flow. Under the action of the standing wave acoustic field, the sheath flow laterally confines the sample flow, so that the sample flow forms a stable narrow band in the middle of the main channel, so as to realize the sorting of particles in the sample flow in the main channel, and the target particles after sorting are output by the target particle outlet of the microfluidic channel 3 and flow into the droplet residence ring 4; the target particles in the droplet residence ring 4 are centrally gathered under the action of the unidirectional rotating acoustic flow. The non-target particles after sorting are discharged by the impurity / waste liquid outlet of the microfluidic channel 3; the impurity / waste liquid outlet is independently discharged and does not communicate with the droplet residence ring 4.

[0034] In a specific implementation, in the sorting stage, the driving frequency f1 is set to be 5-340 MHz, the output power is set to be 20-33 dBm, and the flow ratio of the sample flow to the sheath flow is set to be 0.5-1:2-10, so as to complete the sheath flow limiting and standing wave splitting; In the gathering stage, the driving frequency f2=f1 is set, or 0.9 f1≤f2≤1.1 f2 is satisfied, and the output power can be adjusted independently of the sorting stage, so as to establish a unidirectional ring acoustic flow in the droplet residence ring 4 and realize central gathering.

[0035] Embodiment one: see Figure 1 、 Figure 2 、 Figure 3 、 Figure 5 、 Figure 7 The chip adopts a 128° Y-cut lithium niobate substrate 1, the width w and the gap g of the adjacent electrode fingers of the two pairs of interdigital electrodes 21 and 22 are 50 μm, the working frequency point f is selected to be f≈19.2 MHz according to f·λ=v; in the sorting stage, the phase difference Δφ of the two transducers is 0° / 180°. In order to obtain a stable lateral acoustic pressure gradient, the effective width of the sorting channel is designed to be W≈λ / 2 (tolerance ±10%) according to the engineering matching principle; the geometric relationship between the ring 4 and the second interdigital electrode pair 22 is arranged (L2 coincides with the y axis through O, the inner edge of the array), which is used to fix the gathering site at the center of the circle. Figure 5

[0036] After power-on, f1≈19.2 MHz is locked in a sweep frequency manner, and the maximum outlet separation distance is used as the criterion; the signal generator 501 is set to have an amplitude of 50 mVrms (power amplifier input), and the power amplifier 502 is powered by a direct current power supply 503 at 21 V; the three inlets are operated according to the flow ratio of sheath flow:sample=3:1 (equivalent linear velocity ratio 3:1, and the volume flow rate can be set equivalently in μL / min). The target outlet only communicates with the ring, and the impurity / waste liquid outlet is independently discharged. In the gathering stage, f2=f1 is maintained (or fine-tuned within 0.9-1.1 f1). The window can repeatedly obtain the sorting and central gathering phenomenon on different batches of devices.

[0037] Embodiment two: see​Figure 4 、 Figure 7 、 Figure 10 . The sample is 9 μm and 2 μm mixed particles (PS microspheres), and the parameters are as in Example 1: f1≈19.2 MHz, Δφ=0° / 180°, 50 mVrms (power amplifier input), sheath flow: sample = 3:1. Figure 10 The microscopic contrast diagram of the outlet region is as follows: Figure 10 The undriven part shown in part (a) of FIG. 6 shows that the two types of particles co-flow in the main channel without an obvious separation interface at the bifurcation; Figure 10 The driven part shown in part (b) of FIG. 6 shows that, under the combined action of the SSAW standing wave and the sheath flow limitation, the 9 μm and 2 μm particles are clearly separated at the double-outlet.

[0038] The representative statistics counted according to the outlet two-branch ROIs show that the sorting efficiency can reach about 99% (representative results of a single device can reach more than 99%) ; if the frequency is excessively reduced, the separation boundary will become poor, and the separation phenomenon can be reproduced after the matching is restored. This example proves that, under the condition of 19.2 MHz corresponding to a 50 μm line width (w=g), online and label-free sorting of 9 μm / 2 μm particle diameter combinations can be achieved.

[0039] Example Three: see Figure 5 、 Figure 6 、 Figure 11 After the sorting in Example Two is completed, only the target particle outlet is connected to the circular ring 4 to form a standing droplet; the switching unit 504 connects the radio frequency drive to the second interdigital electrode pair 22, and f2=f1≈19.2 MHz (other parameters are the same as in Example One). Figure 11 The microscopic contrast diagram of the circular ring is as follows: Figure 11 The undriven part shown in part (a) of FIG. 8 shows that the 9 μm particles are uniformly dispersed in the droplet; Figure 11 The driven part shown in part (b) of FIG. 8 shows that a unidirectional circular acoustic flow + radial convergence is formed in the circular ring, and the 9 μm particles form a stable high-density aggregation spot at the center O of the circle, and reach a steady state within tens of seconds.

[0040] This example shows that geometric alignment (L2 passes through O, and the inner edge of the array coincides with the y-axis) can pin the aggregation site at the center of the circle, facilitating microscopic counting and small-volume recovery; if the alignment is deviated or the power is excessively reduced, the aggregation time will be prolonged or eccentric, and the phenomenon can be reproduced after the alignment is restored and the appropriate power is restored.

Claims

1. A yeast cell directional sorting and aggregation chip based on surface acoustic wave driving, characterized in that, include: The piezoelectric substrate (1), two interdigitated electrode pairs, microfluidic channels (3) and droplet-residing rings (4) are included. Two interdigitated electrode pairs are disposed on the piezoelectric substrate (1); The microfluidic channel (3) is provided between the first interdigital electrode pairs (21); the microfluidic channel (3) consists of three inlets, two outlets and a main channel connecting the inlets and outlets, wherein the middle inlet is used to inject a sample flow containing target particles and non-target particles, and the two side inlets are used to inject sheath flow; the two outlets are the target particle outlet and the impurity / waste liquid outlet, respectively. The droplet-retention ring (4) is provided between the second interdigital electrode pair (22); and the droplet-retention ring (4) is only in fluid communication with the outlet of the target particle.

2. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 1, characterized in that: The first interdigital electrode pair (21) and the second interdigital electrode pair (22) are both composed of two sets of interdigital electrodes arranged opposite to each other; each set of interdigital electrodes includes 25 to 40 pairs of interlaced electrode fingers; and the finger width of the electrode fingers is w, the finger gap between two adjacent electrode fingers is g, and w and g are respectively set in the range of 3 to 150 μm.

3. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 2, characterized in that: The finger width w and the finger gap g satisfy w=g=λ / 4, where λ is the wavelength of the surface acoustic wave propagating on the piezoelectric substrate; the driving frequency f of the interdigitated electrode and the phase velocity v of the surface acoustic wave satisfy: f·λ=v.

4. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 1, characterized in that: The center line of the main channel of the microfluidic channel (3) passes through the acoustic field interaction area between the two sets of interdigital electrodes in the first interdigital electrode pair (21); Take the center of the droplet-residing ring (4) as the origin O, take the straight line passing through O and perpendicular to the center line of the main channel in the microfluidic channel (3) as the y-axis, and take the straight line passing through O and parallel to the center line of the main channel in the microfluidic channel (3) as the x-axis, thereby establishing a rectangular coordinate system O–xy; The two sets of interdigitated electrodes in the second interdigitated electrode pair (22) are located in the second and fourth quadrants or the first and third quadrants of the rectangular coordinate system O–xy, respectively, and the geometric center line L2 of the second interdigitated electrode pair (22) passes through the origin O; In the second interdigital electrode pair (22), the edge of the electrode finger on the side closest to the y-axis coincides with the y-axis, and the extension direction of the electrode finger of each interdigital electrode is parallel to the x-axis.

5. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 1, characterized in that: The microfluidic channel (3) and the droplet-retaining ring (4) are both made of polydimethylsiloxane (PDMS). The thickness of the microfluidic channel (3) is 2-7 mm; The thickness of the droplet-retaining ring (4) is 0.1–1 mm; The piezoelectric substrate (1) is made of 128° Y-cut lithium niobate.

6. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 1, characterized in that: The metal materials of the first interdigital electrode pair (21) and the second interdigital electrode pair (22) are selected from one or more of aluminum (Al), gold (Au), chromium (Cr), and titanium (Ti), preferably using chromium (Cr) or titanium (Ti) as the adhesion layer and aluminum (Al) or gold (Au) as the conductive layer; the total thickness of the metal layer is 200-300 nm.

7. The surface acoustic wave driven yeast cell directional sorting and aggregation chip according to claim 1, characterized in that: The microfluidic channel (3) and the droplet-residing ring (4) are bonded to the piezoelectric substrate (1) by oxygen plasma surface activation, and the bonded chip is subjected to post-curing treatment at 65°C to 90°C for 30 to 120 minutes to strengthen the bonding of the chip.

8. A control system for driving a surface acoustic wave driven yeast cell directional sorting and aggregation chip as described in any one of claims 1 to 7, characterized in that, include: Radio frequency signal source (501), power amplifier (502), DC power supply (503), switching unit (504), first micro-injection pump (506), second micro-injection pump (507), sheath flow injector (508), sample injector (509); The DC power supply (503) supplies power to the power amplifier (502); The adjustable radio frequency signal output by the radio frequency signal source (501) is amplified by the power amplifier (502), and then the switching unit (504) inputs the amplified adjustable radio frequency signal to the first interdigital electrode pair (21) during the sorting stage, thereby establishing a standing wave sound field in the action area of ​​the microfluidic channel (3), or inputting the amplified adjustable radio frequency signal to the second interdigital electrode pair (22) during the aggregation stage, thereby forming a unidirectional rotating acoustic flow in the droplet residence ring (4); The sheath flow injector (508) driven by the first micro-injection pump (506) pushes sheath flow into the two inlets of the microfluidic channel (3); The sample syringe (509) is driven by the second micro-injection pump (507) to push the sample flow into the middle inlet of the microfluidic channel (3); Under the action of the standing wave acoustic field, the sheath flow laterally constrains the sample flow, so that the sample flow forms a stable narrow band in the middle of the main channel, so as to achieve the sorting of particles in the sample flow in the main channel. The sorted target particles are output from the target particle outlet of the microfluidic channel (3) and flow into the droplet retention ring (4); the sorted non-target particle fluid is discharged from the impurity / waste liquid outlet of the microfluidic channel (3). The target particles within the droplet-residing ring (4) are centrally aggregated under the action of the unidirectional rotating acoustic flow.

9. The control system according to claim 8, characterized in that: During the sorting stage, the driving frequency f1 of the radio frequency signal source (501) is between 5 and 340 MHz, and the output power is between 20 and 33 dBm; the flow rate ratio between the sample flow and the sheath flow is (0.5~1):(2~10); During the aggregation phase, the driving frequency of the radio frequency signal source (501) is f2=f1 or satisfies 0.9×f1≤f2≤1.1×f1.

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