Microfluidic Actuators

Abstract

A microfluidic actuator comprises a substrate, a cavity layer, a vibration layer, a lower electrode layer, an upper electrode layer, an orifice plate layer and a flow channel layer. The substrate is formed with an outflow hole, a plurality of first inflow holes and a second inflow hole by an etching process. The cavity layer is formed on the substrate, and a flow storage chamber is formed by an etching process. The vibration layer is formed on the cavity layer. The lower electrode layer is formed on the vibration layer. The piezoelectric actuation layer is formed on the lower electrode layer. The upper electrode layer is formed on the piezoelectric actuation layer. The orifice plate layer is formed with an outflow port and an inflow port by an etching process. The flow channel layer is formed on the orifice plate layer, and an outflow channel and an inflow channel are formed by a photolithography process, and are bonded to the substrate. A driving power supply is provided to the upper electrode layer and the lower electrode layer to drive and control the vibration layer to produce an up and down displacement to complete fluid transmission.

Description

Technical Field

[0001] This case relates to an actuator, and more particularly to a microfluidic actuator made using a micro-electromechanical semiconductor film. Background Art

[0002] At present, in various fields, whether it is medicine, computer technology, printing, energy and other industries, products are developing in the direction of refinement and miniaturization. Among them, fluid actuators contained in products such as micro pumps, sprayers, inkjet heads, industrial printing devices, etc. are their key technologies.

[0003] With the rapid development of technology, the application of fluid delivery structures is becoming more and more diversified, including industrial applications, biomedical applications, healthcare, electronic cooling, etc., and even the recently popular wearable devices can all be seen. It can be seen that traditional fluid actuators have gradually tended towards device miniaturization and flow maximization.

[0004] In the prior art, although there are microfluidic actuators made using micro-electromechanical processes, the displacement of the piezoelectric layer of the known microfluidic actuators is too small when they are actuated, resulting in insufficient flow rate. Therefore, how to break through the technical bottleneck through innovative structures is an important part of development. Summary of the invention

[0005] The main purpose of this case is to provide a microfluidic actuator that is made using a micro-electromechanical process and can transmit fluid. The microfluidic actuator of this case is made using a semiconductor film, so the depth of its fluid storage chamber can be designed to be very shallow, thereby increasing the fluid compression ratio during actuation to compensate for the disadvantage of too small displacement of the piezoelectric layer.

[0006] A general implementation of the present case is a microfluidic actuator, comprising a substrate, a cavity layer, a vibration layer, a lower electrode layer, a piezoelectric actuation layer, an upper electrode layer, an orifice plate layer and a flow channel layer. The substrate has a first surface and a second surface, and an outlet groove, an inlet groove, an outflow hole, a plurality of first inflow holes and a second inflow hole are formed by an etching process. The outlet groove is connected to the outflow hole. The inlet groove is connected to the plurality of first inflow holes and the second inflow hole. The cavity layer is formed on the first surface of the substrate by a deposition process, and a flow storage chamber is formed by an etching process. The flow storage chamber is connected to the outflow hole, the plurality of first inflow holes and the second inflow hole. The vibration layer is formed on the cavity layer by a deposition process. The lower electrode layer is formed on the vibration layer by a deposition process and an etching process. The piezoelectric actuation layer is formed on the lower electrode layer by a deposition process and an etching process. The upper electrode layer is formed on the piezoelectric actuation layer through a deposition process and an etching process. The orifice layer is formed with an outlet and an inlet through an etching process. The flow channel layer is formed on the orifice layer through a dry film material rolling process, and an outlet channel, an inlet channel and a plurality of columnar structures are formed through a photolithography process, and are bonded to the second surface of the substrate through a flip chip alignment process and a hot pressing process. The outlet of the orifice layer is connected to the outlet groove of the substrate through the outlet channel. The inlet of the orifice layer is connected to the inlet groove of the substrate through the inlet channel. A driving power supply with different phase charges is provided to the upper electrode layer and the lower electrode layer to drive and control the vibration layer to produce an up and down displacement, so that the fluid is sucked in from the inlet, flows through a plurality of first inlet holes and a second inlet hole to the storage chamber, and finally is squeezed through the outlet hole and discharged from the outlet to complete the fluid transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a cross-sectional schematic diagram of the microfluidic actuator in this case.

[0008] Figures 2A to 2K A schematic diagram showing the manufacturing steps of the microfluidic actuator in this case.

[0009] Figure 3 Schematic diagram of a top view of the microfluidic actuator in this case.

[0010] Figure 4 Schematic diagram of the bottom view of the microfluidic actuator in this case.

[0011] FIG. 5A to FIG. 5C The schematic diagram of the etching steps of the inlet hole of the fluid actuator in this case is decomposed.

[0012] FIG. 6A to FIG. 6B Schematic diagram of the operation of the microfluidic actuator in this case.

[0013] Description of Reference Numerals

[0014] 100: Microfluidic Actuators

[0015] 1a: Substrate

[0016] 11a: First surface

[0017] 12a: Second surface

[0018] 13a: Exit groove

[0019] 14a: Inlet groove

[0020] 15a: Outflow hole

[0021] 16a: First inlet hole

[0022] 17a: Second inlet hole

[0023] 1b: Cavity layer

[0024] 11b: Reservoir chamber

[0025] 1c: Vibration layer

[0026] 1d: Lower electrode layer

[0027] 1e: Piezoelectric actuation layer

[0028] 1f: Upper electrode layer

[0029] 1g: Mask layer

[0030] 11g: First flow hole

[0031] 12g: Second flow hole

[0032] 13g: Third flow hole

[0033] 1h: Orifice layer

[0034] 11h: Outlet

[0035] 12h: Inlet

[0036] 1i: Runner layer

[0037] 11i: Outflow channel

[0038] 12i: Inlet channel

[0039] 13i: Columnar structure

[0040] e: buffer distance

[0041] t: Overetching depth

[0042] d: Perforation depth

[0043] s: perforation diameter

[0044] r: cavity depth

[0045] r': side erosion distance

[0046] L: Over-erosion distance

[0047] M: Action area DETAILED DESCRIPTION

[0048] Some typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different aspects without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially for illustrative purposes rather than for limiting the present invention.

[0049] The microfluidic actuator in this case is used to transport fluids. Figure 1 In the present embodiment, the microfluidic actuator 100 includes: a substrate 1a, a cavity layer 1b, a vibration layer 1c, a lower electrode layer 1d, a piezoelectric actuation layer 1e, an upper electrode layer 1f, an orifice layer 1h, and a flow channel layer 1i. The flow channel layer 1i, the orifice layer 1h, the substrate 1a, the cavity layer 1b, the vibration layer 1c, the lower electrode layer 1d, the piezoelectric actuation layer 1e, and the upper electrode layer 1f are stacked and combined in sequence to form a whole, and their structure is described as follows.

[0050] See also Figure 2A In the embodiment of the present case, the substrate 1a is a silicon substrate. The substrate 1a has a first surface 11a and a second surface 12a opposite to the first surface 11a. In the embodiment of the present case, the cavity layer 1b is formed on the first surface 11a of the substrate 1a by a silicon dioxide material deposition process. The deposition process can be a physical vapor deposition process (PVD), a chemical vapor deposition process (CVD) or a combination of the two, but not limited thereto. In the embodiment of the present case, the vibration layer 1c is formed on the cavity layer 1b by a silicon nitride material deposition process. In the embodiment of the present case, the lower electrode layer 1d is formed on the vibration layer 1c by a metal material deposition process. The lower electrode layer 1d is a platinum metal material or a titanium metal material, but not limited thereto. In the embodiment of the present case, the piezoelectric actuation layer 1e is formed on the lower electrode layer 1d by a piezoelectric material deposition process. In the present embodiment, the upper electrode layer 1f is formed on the piezoelectric actuation layer 1e by a metal material deposition process, and the upper electrode layer 1f is a gold metal material or an aluminum metal material, but is not limited thereto. It is worth noting that, Figure 2A The structure shown can be manufactured using existing foundry technology and therefore has the advantage of low cost.

[0051] See also Figure 2BIn the present embodiment, the lower electrode layer 1d, the piezoelectric actuation layer 1e and the upper electrode layer 1f are etched by a photolithography etching process to define an active region M. It is worth noting that in the present embodiment, the etching process can be a wet etching process, a dry etching process or a combination of the two, but is not limited thereto.

[0052] See also Figure 2C In the present embodiment, the second surface 12a of the substrate 1a is etched by a dry etching process to form an outlet groove 13a and an inlet groove 14a. The outlet groove 13a and the inlet groove 14a have the same etching depth, and the etching depth is etched between the first surface 11a and the second surface 12a and does not contact the cavity layer 1b.

[0053] See also Figure 2D and Figure 2E In the embodiment of the present case, a mask layer 1g is formed on the second surface 12a of the substrate 1a and in the outlet groove 13a and the inlet groove 14a by a silicon dioxide material deposition process. The mask layer 1g is then formed into a first flow hole 11g in the outlet groove 13a, and a plurality of second flow holes 12g and a third flow hole 13g in the inlet groove 14a by a precision perforation process. In the embodiment of the present case, the aperture of the first flow hole 11g is larger than the aperture of the third flow hole 13g, and the aperture of the third flow hole 13g is larger than the aperture of each of the plurality of second flow holes 12g, but not limited thereto. The perforation depth of the first flow hole 11g, the plurality of second flow holes 12g and the third flow hole 13g is until they contact with the substrate 1a, so that the substrate 1a is exposed. In the embodiment of the present case, the precision perforation process is an excimer laser processing process, but not limited thereto.

[0054] See also Figure 2F and Figure 3 In the embodiment of the present case, the substrate 1a is etched by a low-temperature deep etching process to form a flow outflow hole 15a, a plurality of first flow inflow holes 16a and a second flow inflow hole 17a of the substrate 1a. The flow outflow hole 15a is formed by etching along the first flow hole 11g until it contacts the cavity layer 1b, the plurality of first flow inflow holes 16a are formed by etching along the plurality of second flow holes 12g until they contact the cavity layer 1b, and the second flow inflow hole 17a is formed by etching along the third flow hole 13g until it contacts the cavity layer 1b. In the embodiment of the present case, the low-temperature deep etching process is a deep reactive ion etching process (BOSCH Process), but is not limited thereto. Please refer to Figure 2E and Figure 5AIn the embodiment of the present case, when the mask layer 1g is formed into the first flow hole 11g, the plurality of second flow holes 12g and the third flow hole 13g by the excimer laser processing process, in order to avoid the deviation of the perforation position or the perforation angle, a buffer distance e is reserved on the side walls of the outlet groove 13a and the inlet groove 14a. In addition, the deep reactive ion etching process (BOSCH Process) is used to etch only the silicon material of the substrate 1a, so the excimer laser processing process is used to leave an over-etching depth t on the substrate 1a, which is beneficial for the substrate 1a to be able to accurately and easily etch from the over-etching depth t to form the outflow hole 15a, the plurality of first inflow holes 16a and the second inflow hole 17a. In the embodiment of the present case, the minimum aperture of the outflow hole 15a, the plurality of first inflow holes 16a and the second inflow hole 17a is 5 to 50 microns (μm), and the aperture size depends on the properties of the fluid. Please refer to the following. Figure 2F and Figure 5B The outflow hole 15a, each of the first inflow holes 16a and the second inflow hole 17a have a perforation depth d and a perforation aperture s, and the aspect ratio d / s of the formed hole can reach 40. Considering the appropriate aspect ratio d / s of the hole in the implementation of this processing process can avoid the high temperature generated by the processing affecting the polarity distribution of the rear-end piezoelectric material and causing a depolarization reaction.

[0055] See also Figure 2G In the embodiment of the present case, the cavity layer 1b is further etched into a reservoir chamber 11b by a wet etching process. That is, the etching liquid flows in from the first flow hole 11g, the multiple second flow holes 12g and the third flow hole 13g, flows to the cavity layer 1b through the outflow hole 15a, the multiple first inflow holes 16a and the second inflow hole 17a, and then etches and releases the removed part of the cavity layer 1b, thereby defining a reservoir chamber 11b. In this way, the reservoir chamber 11b is connected to the outflow hole 15a, the multiple first inflow holes 16a and the second inflow hole 17a. In the embodiment of the present case, the wet etching process uses hydrofluoric acid (HF) etching liquid to etch the cavity layer 1b, but it is not limited to this. In the embodiment of the present case, the thickness of the cavity layer 1b is 1 to 5 micrometers (μm), but it is not limited to this. It is worth noting that when the reservoir chamber 11b is formed by the wet etching process, the mask layer 1g will also be removed. After the reservoir chamber 11b is formed and the mask layer 1g is removed, the outlet groove 13a of the substrate 1a is connected to the outlet hole 15a, and the inlet groove 14a is connected to the first inlet holes 16a and the second inlet holes 17a. Figure 2G and Figure 5CIn the present embodiment, the wet etching process is usually isotropic etching. In the present embodiment, when etching the liquid storage chamber 11b, the liquid storage chamber 11b has a cavity depth r, which is equal to the thickness of the cavity layer 1b, and the side etching distance generated by the wet etching is r', so the cavity depth r is equal to the side etching distance r', that is, an isotropic etching. In addition, since the apertures of the outflow hole 15a, each of the first inflow hole 16a and the second inflow hole 17a are only between 5 and 50 microns (μm), and the cavity depth r is only between 1 and 5 microns (μm), an over-etching is required when etching the liquid storage chamber 11b to extend the etching time in order to remove the unetched residual material. In the present embodiment, when the wet etching process is performed to form the liquid storage chamber 11b, an overetching distance L is generated, and the overetching distance L is greater than the side etching distance r', so that the silicon dioxide material within the liquid storage chamber 11b can be completely removed.

[0056] See also Figure 2H and Fig.2I In the embodiment of the present case, an orifice plate layer 1h is provided, and an outlet 11h and an inlet 12h are etched out of the orifice plate layer 1h through an etching process. In the embodiment of the present case, the etching process of the orifice plate layer 1h can be a wet etching process, a dry etching process, or a combination of the two, but not limited thereto. In the embodiment of the present case, the orifice plate layer 1h is a stainless steel material or a glass material, but not limited thereto.

[0057] See also Figure 2J , Figure 2K and Figure 4 In the present embodiment, the flow channel layer 1i is formed on the orifice plate layer 1h by a dry film material rolling process, and an outflow channel 11i, an inflow channel 12i and a plurality of columnar structures 13i are formed on the flow channel layer 1i by a photolithography process, and the outflow channel 11i is connected to the outflow port 11h of the orifice plate layer 1h, and the inflow channel 12i is connected to the inflow port 12h of the orifice plate layer 1h. In the present embodiment, a plurality of columnar structures 13i are formed in an alternating arrangement in the inflow channel 12i (such as Figure 4 ) is used to filter impurities in the fluid. In the present embodiment, the dry film material is a photosensitive polymer dry film, but is not limited thereto.

[0058] Please go back Figure 1 Finally, the flow channel layer 1i is bonded to the second surface 12a of the substrate 1a through a flip chip alignment process and a hot pressing process to form the microfluidic actuator 100 of the present invention. Thus, the outlet 11h of the orifice layer 1h is connected to the outlet groove 13a of the substrate 1a through the outlet channel 11i of the flow channel layer 1i; and the inlet 12h of the orifice layer 1h is connected to the inlet groove 14a of the substrate 1a through the inlet channel 12i of the flow channel layer 1i.

[0059] See also Fig. 6A and Figure 6B In the present embodiment, the specific operation method of the microfluidic actuator 100 is to provide a driving power source with opposite phase charges to the upper electrode layer 1f and the lower electrode layer 1d to drive and control the vibration layer 1c to generate an upward and downward displacement. Fig. 6A As shown, when a positive voltage is applied to the upper electrode layer 1f and a negative voltage is applied to the lower electrode layer 1d, the piezoelectric actuation layer 1e drives the vibration layer 1c to move in a direction away from the substrate 1a, thereby the external fluid is sucked into the microfluidic actuator 100 through the inlet 12h of the orifice layer 1h, and the fluid entering the microfluidic actuator 100 then passes through the inlet channel 12i of the flow channel layer 1i, the inlet groove 14a of the substrate 1a, and the multiple first inlet holes 16a and / or second inlet holes 17a of the substrate 1a in sequence, and finally gathers in the storage chamber 11b of the cavity layer 1b. Figure 6B As shown, the electrical properties of the upper electrode layer 1f and the lower electrode layer 1d are then converted, and a negative voltage is applied to the upper electrode layer 1f and a positive voltage is applied to the lower electrode layer 1d. In this way, the vibration layer 1c is displaced toward the direction close to the substrate 1a, so that the volume inside the flow storage chamber 11b is compressed by the vibration layer 1c, so that the fluid collected in the flow storage chamber 11b is able to pass through the outflow hole 15a of the substrate 1a, the outlet groove 13a of the substrate 1a and the outflow channel 11i of the flow channel layer 1i in sequence, and then be discharged from the outlet 11h of the orifice layer 1h to the outside of the microfluidic actuator 100, thereby completing the fluid transmission.

[0060] It is worth noting that when the microfluidic actuator 100 inhales external fluid, part of the external fluid will be inhaled into the microfluidic actuator 100 through the outlet 11h of the orifice layer 1h. However, since the position of the outflow hole 15a of the substrate 1a corresponding to the vibration layer 1c is not the area with the largest displacement, the amount of external fluid inhaled from the outlet 11h is relatively small. When the microfluidic actuator 100 discharges fluid, the multiple columnar structures 13i of the flow channel layer 1i will have a damping effect on the reflowing fluid. In addition, the second inlet hole 17a of the substrate 1a corresponds to the edge position of the vibration layer 1c with the smallest displacement. Therefore, the amount of fluid discharged from the inlet 12h is relatively small.

[0061] Furthermore, it is worth noting that the problem of excessive flow resistance of the plurality of first inlet holes 16 a of the substrate 1 a can be improved by adjusting the voltage waveform and lengthening the actuation time of the microfluidic actuator 100 to absorb the external fluid.

[0062] In summary, this case provides a microfluidic actuator, which is mainly completed by micro-electromechanical semiconductor process, and by applying driving power with different phase charges to the upper electrode layer and the lower electrode layer, the vibration layer is displaced up and down, thereby achieving fluid transmission. In this way, the microfluidic actuator can increase the fluid compression ratio during actuation to compensate for the shortcoming of too small displacement of the piezoelectric layer, achieve the feasibility of transmitting fluid and generate great transmission efficiency in an extremely miniaturized structure, which is of great industrial utilization value, and therefore an application is filed in accordance with the law.

[0063] This case can be modified in various ways by those familiar with this technology, but all of them will not deviate from the scope of protection sought by the attached patent application.

Claims

1. A microfluidic actuator, characterized in that: Include: A substrate having a first surface and a second surface, wherein an outlet groove, an inlet groove, an outlet hole, a plurality of first inlet holes and a second inlet hole are formed by an etching process, wherein the outlet groove is connected to the outlet hole, and the inlet groove is connected to the plurality of first inlet holes and the second inlet hole; A cavity layer is formed on the first surface of the substrate by a deposition process, and a flow storage chamber is formed by an etching process, wherein the flow storage chamber is connected to the outflow hole, the plurality of first inflow holes, and the second inflow hole; a vibration layer formed on the cavity layer by a deposition process; A lower electrode layer is formed on the vibration layer through a deposition process and an etching process; A piezoelectric actuation layer is formed on the lower electrode layer through a deposition process and an etching process; An upper electrode layer is formed on the piezoelectric actuation layer by a deposition process and an etching process; An orifice plate layer, formed with an outlet and an inlet through an etching process; and A flow channel layer is formed on the orifice plate layer by a dry film material rolling process, an outflow channel, an inflow channel and a plurality of columnar structures are formed by a photolithography process, and is bonded to the second surface of the substrate by a flip chip alignment process and a hot pressing process, the outflow port of the orifice plate layer is connected to the outlet groove of the substrate through the outflow channel, and the inflow port of the orifice plate layer is connected to the inlet groove of the substrate through the inflow channel; A driving power source with different phase charges is provided to the upper electrode layer and the lower electrode layer to drive and control the vibration layer to produce up and down displacement, so that the fluid is sucked in from the inlet, flows through the multiple first inlet holes and the second inlet holes to the fluid storage chamber, and is finally squeezed through the outlet hole and discharged from the outlet to complete the fluid transmission.

2. The microfluidic actuator according to claim 1, characterized in that: After the fluid is sucked in from the inlet port, it flows into the fluid storage chamber through the inlet channel, the inlet groove, the plurality of first inlet holes and the second inlet holes in sequence.

3. The microfluidic actuator according to claim 1, characterized in that: The fluid in the flow storage chamber is squeezed and sequentially passes through the outflow hole, the outlet groove and the outflow channel and then is discharged from the outflow port.

4. The microfluidic actuator according to claim 1, wherein: The plurality of columnar structures are formed in the inlet channel.

5. The microfluidic actuator according to claim 1, characterized in that: The substrate is a silicon substrate.

6. The microfluidic actuator according to claim 1, wherein: The cavity layer is made of silicon dioxide material.

7. The microfluidic actuator according to claim 1, characterized in that: The lower electrode layer is made of platinum metal material.

8. The microfluidic actuator according to claim 1, characterized in that: The lower electrode layer is made of titanium metal material.

9. The microfluidic actuator according to claim 1, characterized in that: The upper electrode layer is a gold metal material.

10. The microfluidic actuator according to claim 1, characterized in that: The upper electrode layer is made of aluminum metal material.

11. The microfluidic actuator according to claim 1, wherein: The substrate is formed with the outflow hole, the plurality of first inflow holes and the second inflow hole through a deep reactive ion etching process.

12. The microfluidic actuator according to claim 1, wherein: The cavity layer is formed into the current storage cavity through a hydrofluoric acid wet etching process.

13. The microfluidic actuator according to claim 1, wherein: The orifice plate layer is made of stainless steel.

14. The microfluidic actuator according to claim 1, wherein: The hole plate layer is made of glass material.

15. The microfluidic actuator according to claim 1, wherein: The dry film material of the flow channel layer is a photosensitive polymer dry film.

16. The microfluidic actuator according to claim 1, wherein: A positive voltage is applied to the upper electrode layer and a negative voltage is applied to the lower electrode layer, so that the piezoelectric actuation layer drives the vibration layer to move in a direction away from the substrate.

17. The microfluidic actuator according to claim 1, wherein: A negative voltage is applied to the upper electrode layer and a positive voltage is applied to the lower electrode layer, so that the piezoelectric actuation layer drives the vibration layer to move toward a direction close to the substrate.

18. The microfluidic actuator according to claim 1, wherein: Applying a positive voltage to the upper electrode layer and a negative voltage to the lower electrode layer, so that the piezoelectric actuation layer drives the vibration layer to move in a direction away from the substrate, so that the external fluid is sucked into the microfluidic actuator through the inlet port, and the fluid entering the microfluidic actuator flows through the inlet channel, the inlet groove, and the plurality of first inlet holes and the second inlet holes in sequence, and then gathers in the fluid storage chamber; as well as The electrical properties of the upper electrode layer and the lower electrode layer are converted, a negative voltage is applied to the upper electrode layer and a positive voltage is applied to the lower electrode layer, and the vibration layer is displaced toward the direction close to the substrate, so that the volume inside the flow storage chamber is compressed by the vibration layer, so that the fluid collected in the flow storage chamber can pass through the outflow hole, the outlet groove and the outflow channel in sequence and then be discharged from the outlet to the outside of the microfluidic actuator, thereby completing the fluid transmission.

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