Circuit-like programmable microfluidic composite device with programmable interface

Abstract

A circuit-like programmable microfluidic composite device with a programmable interface comprises: a base layer, a binary valve control layer, a flow channel layer, a chamber layer, and a thin film layer, arranged sequentially from bottom to top. The binary valve control layer and the base layer, the flow channel layer and the chamber layer, and the chamber layer and the thin film layer are all plasma-surface treated and precisely bonded together. Through holes are provided between the chamber layer and the flow channel layer at positions corresponding to the cavities and flow channels. Gas is delivered to any selected flow channel through a combined array of binary valves in the binary valve control layer to achieve individual control. The present invention utilizes microfluidic integration (LSI) technology similar to large-scale electronic integrated circuits and multi-layer soft lithography processes to achieve the effect of meticulously programming interface morphology paths and gradients. This allows for real-time programming to achieve precise droplet manipulation, and has the advantages of precise droplet manipulation, strong programmable flexibility, high integration, simple operation, and fast response speed.

Description

Technical Field

[0001] The present invention relates to a technology in the field of microfluidics, in particular to a circuit-simulating programmable microfluidics composite device with a programmable interface. Background Art

[0002] The technology of droplet manipulation on solid surfaces has a wide range of applications in microfluidics, wetting interfaces, biochemistry, and materials. Traditional methods for droplet manipulation include electrowetting, magnetic response, and wetting surfaces. However, these electrowetting and magnetic response technologies rely on external energy and are subject to many restrictions. Most of the existing research in the field of droplets using wetting surfaces only involves a single droplet manipulation path, so that droplets can only be transported along an existing single path, the manipulation is cumbersome, and the liquid repellency is uncontrollable. In addition, the existing microfluidic-based droplet manipulation interface has a slow response and low integration. The droplet manipulation ability and wettability regulation of the microfluidic auxiliary structure are still very dependent on complex and cumbersome microchannel design, and the flexibility, real-time control, and high integration of the interface programmability still need to be improved. Summary of the Invention

[0003] The present invention addresses the shortcomings of the existing technology, which is aimed at the path of single droplet manipulation, so that the droplet can only be transported along the existing single path, resulting in its cumbersome manipulation, uncontrollable liquid repellency, slow response time and low integration. A circuit-like programmable microfluidic composite device with a programmable interface is proposed. It adopts microfluidic integration (LSI) technology similar to large-scale electronic integrated circuits and a multi-layer soft lithography process to solve the problem that the existing technology can control more structures with fewer control components, and can realize programmable droplet operation through the structure. The interface can achieve the effect of carefully programming the interface morphology path and gradient, and can be programmed in real time to achieve precise droplet manipulation. It has the advantages of precise droplet manipulation, strong programmable flexibility, high integration, simple operation, and fast response speed.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to a circuit-like programmable microfluidic composite device with a programmable interface, comprising: a base layer, a binary valve control layer, a flow channel layer, a chamber layer and a thin film layer, which are arranged in sequence from bottom to top, wherein: the binary valve control layer and the base layer, the flow channel layer and the chamber layer, and the chamber layer and the thin film layer are all plasma-surface treated and precisely bonded together, through holes are provided between the chamber layer and the flow channel layer at positions corresponding to cavities and flow channels, and gas is delivered into any selected flow channel through a combined array of binary valves in the binary valve control layer, thereby realizing independent control of each unit.

[0006] The precise bonding specifically includes: bonding the thin film layer to the chamber layer to form a closed chamber with a flexible head, a rigid bottom, and rigid side walls; using plasma precise vertical bonding between the flow channel layer and the binary valve control layer to form a valve where the wide part of the binary valve contacts the flow channel; using plasma bonding between the binary valve control layer and the base layer, and the base layer is used to seal the channel of the binary valve control layer.

[0007] The binary valve control layer is composed of several microfluidic microvalves arranged in a binary pattern. A thin film chip with a binary valve structure is made of the silicone elastomer polydimethylsiloxane (PDMS). A hole is punched at one end of each group of binary valves and connected to a microfluidic multi-channel pressure pump. The binary valve control layer is controlled by the multi-channel microfluidic pressure pump, and the microfluidic positive pressure pump and the microfluidic negative pressure pump are used to respectively control the air intake and exhaust of the programmable interface structure.

[0008] The thin film layer is a thin film made by PDMS spin coating.

[0009] The chamber layer is a hollow structure with holes punched at the bottom of the cavity.

[0010] The flow channel layer includes: an input flow channel and a plurality of branch flow channel points connected in parallel.

[0011] The base layer is preferably made of high-temperature resistant soda-lime glass or polydimethylsiloxane.

[0012] The unit comprises: a branch flow channel point of a flow channel layer and a part of the chamber layer and a part of the film layer sequentially located thereon.

[0013] Technical Effects

[0014] Based on the theory of microfluidic integration (LSI) technology and multi-layer soft lithography, the present invention changes the structural morphology of the interface through the regulation of fluid pressure using microfluidic technology. Through a programmable interface that simulates an integrated circuit using a five-layer soft lithography process and the careful arrangement and combination of binary valves, n×n flexible structures can be controlled using only 2log2n control components. Under the action of a microfluidic multi-channel pressure pump, the gas pressure of each structure can be independently controlled, thereby controlling the reversible deformation of the structure. These structures can be deformed into a specified convex curvature to trigger rigid liquid repellency. For droplet manipulation, it is demonstrated that the surface can be freely programmed through computer control to create carefully designed morphological paths and gradients. Droplets are driven by deforming structures for directional droplet rebound, directional rolling, stopping, and other behaviors. The structure is also specially spliced ​​and adjusted dynamically to extend the transmission distance. It is also widely used in the field of droplet impact anti-icing and has excellent anti-icing and deicing capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 and Figure 2 Schematic diagram of the overall structure of the device of the present invention

[0016] In the figure: 1 film layer, 2 chamber layer, 3 flow channel layer, 4 binary valve control layer, 5 base layer, 6 input flow channel;

[0017] Figure 3 Schematic diagram of the flow channel layer;

[0018] Figure 4 Schematic diagram of the binary valve control layer;

[0019] Figure 5 A single structural principle diagram of the present invention;

[0020] Figure 6 The liquid repellency and anti-icing performance of the present invention are shown in FIG.

[0021] Figure 7 This is a diagram of the deicing performance of the present invention. DETAILED DESCRIPTION

[0022] like Figure 1 and Figure 2 As shown, this embodiment relates to a circuit-like programmable microfluidic composite device with a programmable interface, which is manufactured using a multi-layer soft lithography process and includes: a binary valve control layer 4, a flow channel layer 3 and a chamber layer 2 sequentially arranged on a substrate layer 5, and a thin film layer 1 bonded to the chamber layer 2. Through holes are provided between the chamber layer 2 and the flow channel layer 3 at positions corresponding to the cavities and flow channels. Gas is delivered to any selected flow channel through a combined array of binary valves in the binary valve control layer 4 to achieve independent control of each unit.

[0023] like Figure 3 As shown, the flow channel layer 3 comprises an input flow channel at the top and 64 parallel branching flow channel points, each of which is 200μm wide and 40μm deep. The fabrication process involves first using positive photoresist to spin-coat, expose, develop, and reflow a blank silicon wafer to create a 40μm-high, 200μm-wide arched-cross-section flow channel mold. PDMS is then cast onto the mold and peeled off, forming a PDMS-made flow channel layer with an arched cross-section that transports gas to the 64 flow channel points.

[0024] like Figure 4 As shown, the binary valve control layer includes 6 sets of binary microfluidic valves, where each set of valves is 350μm wide and 30μm narrow. When the pressure of 13kPa is used to pump air into the binary valve control layer, the control layer begins to bulge. When the pressure reaches 32kPa, the binary valve control layer is completely bulged and can be completely closed. Figure 3 The flow channel layer plays the role of controlling the switch of the flow channel layer.

[0025] like Figure 5 Figure 1 shows a cross-sectional view of the unit, with light gray representing gas and white representing no gas. When gas is introduced into the third channel layer and the fourth control layer is closed, the channel is open, allowing gas to enter the chamber layer, causing the topmost film layer to bulge. Conversely, when gas is introduced into the third channel layer and the fourth control layer, the control layer arches upward, closing the channel. This blocks the gas in the channel and prevents it from entering the chamber layer, preventing the top film from bulging.

[0026] This embodiment relates to a method for preparing the above-mentioned circuit-simulating programmable microfluidic composite device, comprising:

[0027] Step 1: Fabrication of a silicon wafer mold: The silicon wafer for the thin film layer was blank. The other three silicon wafers were heated on a hotplate at 200°C for 10 minutes. 2 mL of SU-8 photoresist (MicroChem, Germany) was poured onto each wafer and spun at 3000 rpm for 30 seconds. The wafers were heated at 65°C for 5 minutes and 95°C for 10 minutes. After cooling, the wafers were exposed to an intensity of 5.6 mW cm–2 for 43 seconds and developed with SU-8 developer (MicroChem). The wafers with the chamber and flow layers using positive photoresist were heated at 180°C for 3 hours, while the wafer with the negative resist binary valve control layer was cooled at 150°C for 30 minutes. The wafers were air-cooled to repair the SU8 structures and enhance adhesion between the SU8 and the wafer.

[0028] Step 2: Fabrication of a five-layer circuit-like programmable microfluidic composite device: Sylgard-184 PDMS was mixed in a 10:1 weight ratio and degassed in a vacuum desiccator for 20 minutes. The degassed PDMS was poured onto the wafers for the film layer and control layer and spun at 500 rpm for 5 seconds and 2000 rpm for 30 seconds. After being left on a horizontal surface for 2 hours to ensure smooth film formation, the film layer and binary valve control layer were heated at 120°C for 5 minutes. The degassed PDMS was also poured onto the wafers for the chamber layer and flow layer, allowed to stand for 20 minutes, and then heated at 120°C for 10 minutes.

[0029] Step 3: The thick PDMS layers on the wafers for the chamber layer and the flow layer are peeled off and plasma treated together for 1 minute. After the two layers are bonded to each other, they are punched at the entrance of the chamber layer. The two-layer combination and the wafer for the binary valve control layer are plasma treated for 40 seconds and heated at 120°C for 10 minutes. The bonded three-layer combination is peeled off and holes are punched at the entrance of the binary valve control layer. The three-layer combination and the soda-lime glass substrate are plasma treated for 40 seconds and heated at 120°C for 2 hours. The bonded four-layer combination and the wafer for the thin film layer are plasma treated for 40 seconds and then heated at 150°C for 6 hours. The bonded five-layer combination is peeled off and coated with commercial low surface energy particles Ultra-Ever Dry (Ultra-TechInternational Inc) to complete the fabrication of the above-mentioned circuit-like programmable microfluidic composite device.

[0030] like Figure 6 As shown in the results, in a cryogenic chamber with an ambient temperature of -40°C and a humidity of 10%, and with a surface temperature of -40°C, two supercooled droplets with a diameter of 2 mm at 0°C were used to impact an ordinary surface and a programmable surface at the same speed under the same Weber number (We~31). It was found that when the droplets impacted the ordinary surface, they froze and became solid before they bounced off the surface. Conversely, when the supercooled droplets at 0°C impacted the programmable surface, due to the special arched structure of the programmable surface, the droplets still bounced off the surface in a liquid state after impact. Using a high-speed camera with a frame rate of 5000 fps, calculations showed that the programmable surface can effectively reduce the solid-liquid contact time by more than 30% in low-temperature environments.

[0031] like Figure 7 As shown in the figure, in a cryogenic chamber at -40°C and 10% humidity, a 4-5mm thick layer of ice was applied to the programmable surface. When air was pumped into a single row of structures at a pressure of 40kPa, the ice broke in 312ms. When air was pumped into all structures at 40kPa, the entire ice layer broke through in approximately 500ms. The entire process was recorded using a high-speed camera at a frame rate of 5000fps.

[0032] This embodiment achieves independent control of 8×8 structures through six control components. Following a nature-inspired hybrid rigid-flexible strategy (i.e., symmetry breaking and two-oscillator dynamics), it improves liquid repellency and reduces solid-liquid contact time by over 30%. Furthermore, the surface's anti-icing and de-icing capabilities at low temperatures have been demonstrated, reducing solid-liquid contact time by over 30% in low-temperature environments and breaking a 4mm thick layer of ice in approximately 500ms.

[0033] Furthermore, by creating fine morphological patterns for directional droplet rebound and rolling, specifically using gradient patterns to achieve infinitely variable control, and using dynamic splicing to achieve infinite transmission distance, droplets can be rolled across the interface. As long as the circuit-like programmable microfluidic composite device is large enough, infinite distance transmission can be achieved.

[0034] Compared with the existing technology, this device integrates the advantages of microfluidic large-scale integration technology and multi-layer soft lithography process to develop a five-layer stacked circuit-like programmable microfluidic composite device. It adopts a highly integrated flow channel structure, corresponding to the surface thin film layer connecting the rigid-flexible composite. The entire circuit-like programmable microfluidic composite device adopts pneumatic control, using a microfluidic positive pressure pump to control the air intake of the input flow channel and a microfluidic negative pressure pump to control the air outlet of the device.

[0035] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A circuit-like programmable microfluidic composite device with a programmable interface, characterized in that: include: From bottom to top, the base layer, binary valve control layer, flow channel layer, chamber layer, and film layer are sequentially arranged. The binary valve control layer and base layer, the flow channel layer and chamber layer, and the chamber layer and film layer are all plasma-treated and precisely bonded together. Through holes are provided between the chamber layer and the flow channel layer at positions corresponding to the cavities and flow channels. Gas is delivered to any selected flow channel through the combined array of binary valves in the binary valve control layer, achieving independent control of each unit. The precise bonding specifically includes: bonding the film layer to the chamber layer to form a closed chamber with a flexible head, a rigid bottom, and rigid sidewalls; using plasma precise vertical bonding between the flow channel layer and the binary valve control layer to form a valve where the wide part of the binary valve contacts the flow channel; using plasma bonding between the binary valve control layer and the base layer, the base layer is used to seal the channel of the binary valve control layer; The binary valve control layer comprises a plurality of microfluidic microvalves arranged in a binary pattern. A thin film chip of the binary valve structure is made of polydimethylsiloxane, an organic silicone elastomer. A hole is punched at one end of each set of binary valves, and multiple microfluidic positive and negative pressure pumps are connected to control the binary valve control layer. Specifically, the microfluidic positive pressure pump and the microfluidic negative pressure pump are used to control the air intake and exhaust of the programmable interface structure respectively. The flow channel layer includes: an input flow channel and a plurality of branch flow channel points connected in parallel; The unit comprises: a branch flow channel point of a flow channel layer and a part of the chamber layer and a part of the film layer sequentially located thereon.

2. The circuit-like programmable microfluidic composite device with a programmable interface according to claim 1, wherein: The thin film layer is a thin film made by PDMS spin coating.

3. The circuit-like programmable microfluidic composite device with a programmable interface according to claim 1, wherein: The chamber layer is a hollow structure with holes punched at the bottom of the cavity.

4. The circuit-like programmable microfluidic composite device with a programmable interface according to claim 1, wherein: The base layer is made of high-temperature resistant soda-lime glass or polydimethylsiloxane.

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