Programmable microvalve device and control method for microfluidic transport using the same

Abstract

The invention discloses a programmable microvalve device and a control method for microfluidic transport using the same. The programmable microvalve device comprises a printed circuit board. The printed circuit board is hollowed out from top to bottom to form a rectangular hole having a concave portion on one side in the width direction and an axial hole. The axial hole is adjacent to the other side in the width direction of the rectangular hole and is connected to the rectangular hole. The axial hole is directly opposite to the concave portion. A PDMS solid body matching the rectangular hole is embedded in the rectangular hole. A microchannel is provided in the PDMS solid body along the length direction. A rotating rod is vertically arranged in the axial hole. When the rotating rod is in the initial state, the microchannel is unobstructed and is in an open state at this time. After the rotating rod is rotated 90 degrees, the rotating rod squeezes the PDMS solid body, and the microchannel is deformed and becomes non-obstructed and is in a closed state at this time. The advantage is that there is no risk of leakage in the microchannel during operation, and the need for microfluidic analysis that can be integrated in the printed circuit board can be met.

Description

Technical Field

[0001] The present invention relates to a microvalve device and control technology for controlling microfluid transport in a microfluidic chip, and in particular to a programmable microvalve device and a control method for microfluid transport using the same. Background Art

[0002] The control of microfluidic flow direction is the basis for microfluidic analysis in microfluidic analysis systems. Microvalves are the basic units for realizing microfluidic flow control. Therefore, with the continuous deepening of research on the mechanism and structure of microvalves, new microvalve mechanisms and microvalve structures continue to emerge, thus continuously expanding the application scope of microfluidic analysis, making microfluidic analysis widely used in the fields of DNA analysis, cell analysis, protein analysis, environmental monitoring, and food safety.

[0003] According to whether an external power source is required, microvalves can be divided into two categories, namely active microvalves and passive microvalves. A passive microvalve is a microvalve that does not require off-chip energy supply, but only relies on changes in the microchannel structure to achieve microfluid flow control. Its advantages are no off-chip devices, small geometric dimensions, and easy integration, but its switching speed is relatively slow and the leakage pressure is small. An active microvalve is also called an active microvalve. It can overcome the shortcomings of a passive microvalve, but it requires an external power source. According to the type of power source, active microvalves mainly include pneumatic microvalves, mechanical microvalves, thermal expansion microvalves, electrostatic microvalves, electric microvalves, etc. It requires external power such as magnetic, electrical, thermal or pneumatic to drive the diaphragm inside the microvalve to deform and open or close the microvalve. For example, a typical pneumatic microvalve uses a polydimethylsiloxane film to tilt under the air pressure of the "control channel" to control the flow of microfluids in the microchannel and realize the opening or closing of the microvalve. It requires an off-chip air pump to provide air pressure as the power for the microvalve. Due to the large size of the air pump, it cannot be integrated with the microfluidic chip, and sufficient power needs to be provided for the air pump, which cannot realize on-site microfluidic analysis. Therefore, the pneumatic microvalve has great limitations. The piezoelectric microvalve that realizes microvalve operation through the piezoelectric effect requires a driving voltage of hundreds of volts to cause the piezoelectric crystal to undergo mechanical deformation, thereby causing the polyimide cavity membrane to deform and trigger the microvalve to operate. The advantage of the piezoelectric microvalve is that the microvalve has a fast response time, typically in the millisecond range, and good controllability, but its driving voltage is high, mostly requiring more than 100V, which is not conducive to on-site microfluidic analysis, and its diaphragm displacement is very small, the switch action is limited, and its application is subject to certain restrictions. Phase change microvalve realizes microvalve operation through the volume change caused by the phase change of the phase change material in the microvalve, such as paraffin, gel, ice or heat-sensitive polymer material, which is heated to achieve the flow direction control of microfluid in the microchannel. It needs to integrate an electric heating device to heat the phase change material, so an off-chip power supply is required. Although the principles of several other active microvalves are different, they can all achieve the control of microfluid flow direction. They each have their own advantages and disadvantages and are used in specific occasions.

[0004] As the application of microfluidic analysis becomes more and more extensive, the types and structures of microvalves are also increasing. Programmable microvalves have come into being. According to the requirements of microfluidic analysis, the operator can decide whether to open or close the microvalve according to the needs of the analysis site, thereby controlling the flow direction of the microfluid in the microchannel. It can greatly reduce the requirements of active microvalves for off-chip devices, thereby greatly reducing the analysis cost and has practical significance. For example, the journal Sensors and Actuators A: Physical, Vol. 265, No. 9, 2017, pp. 224-230 published an article titled “Aversatile plug microvalve for microfluidic applications” which proposed a field programmable microvalve. A hole was drilled in a cylindrical polylactic acid rod using a 200°C hot steam gun, and the cylindrical polylactic acid rod with the hole was inserted into a polydimethylsiloxane microchannel. The hole in the inserted cylindrical polylactic acid rod was at the same level as the microchannel. When the cylindrical polylactic acid rod was manually rotated so that the hole in the cylindrical polylactic acid rod was in the same direction as the microchannel, the microfluid could pass through the microchannel and the microvalve opened. When the cylindrical polylactic acid rod was rotated 90 degrees, the hole in the cylindrical polylactic acid rod could not be connected to the microchannel, the microfluid could not be transported in the microchannel, and the microvalve closed. The programmable microvalve has a simple structure and does not require an off-chip power source device. Therefore, it has been integrated with the microfluidic unit in the microfluidic analysis system and is very suitable for on-site microfluidic analysis. However, the disadvantage of the programmable microvalve is that it needs to ensure that the hole in the cylindrical polylactic acid rod is strictly at the same height as the microchannel hole, so that when the microvalve is in the open state, the microfluid in the microchannel can pass through the hole in the cylindrical polylactic acid rod and reach the other side of the microchannel. The programmable microvalve disconnects the microchannel, and there is a risk of leakage when the microvalve is connected to the microchannel, which needs to be improved. At the same time, considering that a part of the microfluidic analysis signal needs to be obtained through an electrical signal, an electrical signal processing circuit is required during the microfluidic analysis, so the integration of the flow path and the circuit needs to be considered. For this reason, it is necessary to study a programmable microvalve integrated in a printed circuit board to meet the needs of microfluidic analysis that can be integrated in a printed circuit board. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a programmable microvalve device and a control method for microfluidic transport using the same, wherein the microchannel of the programmable microvalve device does not have the risk of leakage when in operation and can meet the needs of microfluidic analysis that can be integrated into a printed circuit board.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a programmable microvalve device, characterized in that it includes a printed circuit board, the printed circuit board is hollowed out from top to bottom and is provided with a rectangular hole with a concave part on one side in the width direction and an axial hole, the axial hole is adjacent to the other side of the rectangular hole in the width direction and is connected to the rectangular hole, the position of the axial hole is opposite to the position of the concave part, a PDMS solid body adapted to the rectangular hole is embedded in the rectangular hole, a microchannel is provided in the PDMS solid body along the length direction, a rotating rod is vertically placed in the axial hole, when the rotating rod is in the initial state, the microchannel is unobstructed, and the programmable microvalve device is in the open state; after the rotating rod is rotated 90 degrees, the rotating rod squeezes the PDMS solid body, the microchannel is deformed and becomes non-unobstructed, and the programmable microvalve device is in the closed state; after the rotating rod is rotated 90 degrees in the opposite direction, the rotating rod returns to the initial state.

[0007] The shaft hole is a semi-cylindrical hole, the plane of the semi-cylindrical hole is close to the other side of the width direction of the rectangular hole, so that the arc surface of the semi-cylindrical hole faces the rectangular hole.

[0008] The rotating rod is formed by cutting two parallel side planes on both sides of a semi-cylindrical rod that matches the semi-cylindrical hole. The side planes are perpendicular to the plane of the rotating rod along the diameter direction. The vertical distance between the two side planes is greater than the radius of the semi-cylindrical hole. When the rotating rod is in the initial state, the plane of the rotating rod along the diameter direction is in close contact with one side of the width direction of the PDMS solid body. After the rotating rod is rotated 90 degrees, the side planes squeeze the PDMS solid body. When making the rotating rod, both sides of a semi-cylindrical rod that matches the semi-cylindrical hole are flattened. The vertical distance between the two side planes formed by cutting is greater than the radius of the semi-cylindrical hole. In this way, after the rotating rod is rotated 90 degrees, an extrusion force will inevitably be generated on the PDMS solid body, causing the PDMS solid body to be squeezed toward the concave part.

[0009] The plane of the rotating rod along the diameter direction and the side plane have an arc transition. The connection between the plane of the rotating rod along the diameter direction and the side plane is rounded so that the PDMS solidified body will not be damaged when the rotating rod is rotated.

[0010] A glass slide is connected to the bottom surface of the printed circuit board, and the bottom end surface of the rotating rod abuts against the upper surface of the glass slide. In actual processing, the glass slide can be adhered to the bottom surface of the printed circuit board using double-sided tape, so that the glass slide is located directly below the semi-cylindrical hole, providing a support point for the rotating rod.

[0011] The width of the rectangular hole is 6 to 7 mm, the concave width of the concave part is 1 to 2 mm, and the aperture of the semi-cylindrical hole is 5 to 6 mm. Here, the width of the rectangular hole, the concave width of the concave part and the aperture of the semi-cylindrical hole are a set of reasonable data determined by experiments.

[0012] A control method for microfluidic transport using the programmable microvalve device is characterized by comprising the following steps:

[0013] Microfluid is injected through the inlet of the microchannel, and the microfluid flows toward the outlet of the microchannel; if the operator decides to close the programmable microvalve device, the operator rotates the rotating rod clockwise or counterclockwise to make it rotate 90 degrees, at which time the side plane of the rotating rod contacts one side of the PDMS solid body in the width direction, the rotating rod squeezes the PDMS solid body, the microchannel deforms and becomes non-smooth, and the closing control is achieved, and the microfluid cannot be transported to the outlet of the microchannel through the microchannel; if the operator decides to open the programmable microvalve device, the operator rotates the rotating rod in the opposite direction to make it rotate in the opposite direction by 90 degrees, at which time the PDMS solid body returns to its original state, the plane of the rotating rod along the diameter direction is close to one side of the PDMS solid body in the width direction, the microchannel returns to being unobstructed, and the opening control is achieved, and the microfluid is transported to the outlet of the microchannel through the microchannel.

[0014] Compared with the prior art, the advantages of the present invention are:

[0015] 1) A rotating rod is placed vertically in the shaft hole, and the microchannel in the PDMS solid body is squeezed by rotating the rotating rod. Under the premise of satisfying the operation of the on-site programmable microvalve, the existing programmable microvalve avoids the connection between the microvalve outlet and inlet and the microchannel outlet and inlet, fundamentally solving the leakage problem that may occur in the microchannel when the microvalve is in operation.

[0016] 2) Integrated into the printed circuit board, facilitating the organic integration of flow path and signal processing circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the programmable microvalve device of the present invention;

[0018] Figure 2 It is a schematic diagram of the arrangement of the PDMS solid body, the rotating rod and the glass slide in the programmable microvalve device of the present invention;

[0019] Figure 3 It is a top view of the programmable microvalve device of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings.

[0021] Embodiment 1:

[0022] A programmable microvalve device proposed in this embodiment, as shown in the figure, includes a printed circuit board 1, and a rectangular hole 11 with a concave portion 111 on one side in the width direction and an axial hole 12 are provided through the upper and lower hollows of the printed circuit board 1, the axial hole 12 is adjacent to the other side of the rectangular hole 11 in the width direction and is connected to the rectangular hole 11, and the position of the axial hole 12 is opposite to the position of the concave portion 111, and a PDMS solid body 2 adapted to the rectangular hole 11 is embedded in the rectangular hole 11, a microchannel 3 is provided in the PDMS solid body 2 along the length direction, and a rotating rod 4 is vertically placed in the axial hole 12, and when the rotating rod 4 is in the initial state, the microchannel 3 is unobstructed, and the programmable microvalve device is in the open state; after the rotating rod 4 rotates 90 degrees, the rotating rod 4 squeezes the PDMS solid body 2, and the microchannel 3 is deformed and becomes non-unobstructed, and the programmable microvalve device is in the closed state; after the rotating rod 4 rotates 90 degrees in the opposite direction, the rotating rod 4 returns to the initial state.

[0023] In this embodiment, the axial hole 12 is a semi-cylindrical hole, and the plane of the semi-cylindrical hole is adjacent to the other side of the rectangular hole 11 in the width direction, so that the arc surface of the semi-cylindrical hole faces the rectangular hole 11; the rotating rod 4 is formed by cutting the two sides of a semi-cylindrical rod that is compatible with the semi-cylindrical hole into two parallel side planes 41, and the side plane 41 is perpendicular to the plane 42 of the rotating rod 4 along the diameter direction, and the vertical distance between the two side planes 41 is greater than the radius of the semi-cylindrical hole. When the rotating rod 4 is in the initial state, the plane 42 of the rotating rod 4 along the diameter direction is close to one side of the PDMS solidified body 2 in the width direction, and the side plane 41 squeezes the PDMS solidified body 2 after the rotating rod 4 is rotated 90 degrees. When making the rotating rod 4, both sides of a semi-cylindrical rod that matches the semi-cylindrical hole are flattened, and the vertical distance between the two side planes 41 formed by cutting is larger than the radius of the semi-cylindrical hole. In this way, after the rotating rod 4 rotates 90 degrees, it will inevitably generate an extrusion force on the PDMS solidified body 2, causing the PDMS solidified body 2 to be squeezed toward the concave part 111.

[0024] In this embodiment, the plane 42 along the diameter direction of the rotating rod 4 and the side plane 41 are in an arc transition. The connection between the plane 42 along the diameter direction of the rotating rod 4 and the side plane 41 is rounded so that the PDMS solidified body 2 will not be damaged when the rotating rod 4 is rotated.

[0025] In this embodiment, a glass slide 5 is connected to the bottom surface of the printed circuit board 1, and the bottom end surface of the rotating rod 4 abuts against the upper surface of the glass slide 5. In actual processing, the glass slide 5 can be adhered to the bottom surface of the printed circuit board 1 using double-sided tape, so that the glass slide 5 is located directly below the semi-cylindrical hole, providing a support point for the rotating rod 4.

[0026] In this embodiment, the width W1 of the rectangular hole 11 is 6 to 7 mm, such as 6 mm; the concave width W2 of the concave portion 111 is 1 to 2 mm, such as 1.5 mm; the aperture D of the semi-cylindrical hole is 5 to 6 mm, such as 5 mm. Here, the defined width W1 of the rectangular hole 11, the concave width W2 of the concave portion 111, and the aperture D of the semi-cylindrical hole are a set of reasonable data determined by experiments.

[0027] In this embodiment, the printed circuit board 1 is a blank printed circuit board without electronic components; the shape of the PDMS solidified body 2 is the same as the shape of the rectangular hole 11, the PDMS solidified body 2 can just be embedded in the rectangular hole 11, and the height of the PDMS solidified body 2 is consistent with the height of the rectangular hole 11; when embedding the PDMS solidified body 2 containing the microchannel 3, firstly, uncured gel-state PDMS is coated on the four walls of the PDMS solidified body 2 containing the microchannel 3, and the gel-state PDMS will not flow freely after coating, and then the PDMS solidified body 2 containing the microchannel 3 can be firmly embedded in the rectangular hole 11 by curing in a constant temperature box at 200 degrees Celsius for about 2 hours; the rotating rod 4 is a plastic rotating rod.

[0028] Embodiment 2:

[0029] This embodiment proposes a control method for microfluidic transport using the programmable microvalve device of the first embodiment, which includes the following steps:

[0030] The microfluid is injected through the inlet 31 of the microchannel 3, and the microfluid flows toward the outlet 32 ​​of the microchannel 3; if the operator decides to close the programmable microvalve device, the operator rotates the rotating rod 4 clockwise or counterclockwise to rotate it 90 degrees, at which time the side plane 41 of the rotating rod 4 contacts one side of the width direction of the PDMS solid body 2, the rotating rod 4 squeezes the PDMS solid body 2, and the concave portion 111 faces the semi-cylindrical hole, that is, the side plane 41 of the rotating rod 4 faces the protruding portion on the printed circuit board 1 corresponding to the concave portion 111, and when the rotating rod 4 and the printed circuit board are in contact, the PDMS solid body 2 is pressed against the concave portion 111. 1, the microchannel 3 is deformed and becomes non-smooth, and the closing control is realized. The microfluid cannot be transported to the outlet 32 ​​of the microchannel 3 through the microchannel 3; if the operator decides to open the programmable microvalve device, the operator rotates the rotating rod 4 in the opposite direction to make it rotate 90 degrees in the opposite direction. At this time, the PDMS solid body 2 returns to its original state, and the plane 42 of the rotating rod 4 along the diameter direction is close to one side of the PDMS solid body 2 in the width direction. The microchannel 3 is restored to be unobstructed, and the opening control is realized. The microfluid is transported to the outlet 32 ​​of the microchannel 3 through the microchannel 3.

Claims

1. A programmable microvalve device, characterized in that The invention comprises a printed circuit board, wherein the printed circuit board is provided with a rectangular hole having a concave portion on one side in the width direction and an axial hole through the upper and lower hollows, the axial hole is adjacent to the other side in the width direction of the rectangular hole and is connected with the rectangular hole, the position of the axial hole is directly opposite to the position of the concave portion, a PDMS solid body matching the rectangular hole is embedded in the rectangular hole, a microchannel is provided in the PDMS solid body along the length direction, a rotating rod is vertically placed in the axial hole, when the rotating rod is in the initial state, the microchannel is unobstructed, and the programmable microvalve device is in the open state; after the rotating rod is rotated 90 degrees, the rotating rod squeezes the PDMS solid body, the microchannel is deformed and becomes non-unobstructed, and the programmable microvalve device is in the closed state; after the rotating rod is rotated 90 degrees in the opposite direction, the rotating rod returns to the initial state; The shaft hole is a semi-cylindrical hole, the plane of the semi-cylindrical hole is close to the other side of the width direction of the rectangular hole, so that the arc surface of the semi-cylindrical hole faces the rectangular hole; The rotating rod is formed by cutting two sides of a semi-cylindrical rod adapted to the semi-cylindrical hole into two parallel side planes, the side planes are perpendicular to the plane of the rotating rod along the diameter direction, the vertical distance between the two side planes is greater than the radius of the semi-cylindrical hole, and when the rotating rod is in the initial state, the plane of the rotating rod along the diameter direction is closely attached to one side of the PDMS solidified body in the width direction, and after the rotating rod is rotated 90 degrees, the side plane squeezes the PDMS solidified body; A circular arc transition between the plane of the rotating rod along the diameter direction and the side plane; The width of the rectangular hole is 6 to 7 mm, the concave width of the concave part is 1 to 2 mm, and the aperture of the semi-cylindrical hole is 5 to 6 mm.

2. The programmable microvalve device according to claim 1, characterized in that A glass slide is connected to the bottom surface of the printed circuit board, and the bottom end surface of the rotating rod abuts against the upper surface of the glass slide.

3. A method for controlling microfluidic transport using the programmable microvalve device according to claim 1, characterized in that The following steps are involved: Microfluid is injected through the inlet of the microchannel, and the microfluid flows toward the outlet of the microchannel; if the operator decides to close the programmable microvalve device, the operator rotates the rotating rod clockwise or counterclockwise to make it rotate 90 degrees, at which time the side plane of the rotating rod contacts one side of the PDMS solid body in the width direction, the rotating rod squeezes the PDMS solid body, the microchannel deforms and becomes non-smooth, and the closing control is achieved, and the microfluid cannot be transported to the outlet of the microchannel through the microchannel; if the operator decides to open the programmable microvalve device, the operator rotates the rotating rod in the opposite direction to make it rotate in the opposite direction by 90 degrees, at which time the PDMS solid body returns to its original state, the plane of the rotating rod along the diameter direction is close to one side of the PDMS solid body in the width direction, the microchannel returns to being unobstructed, and the opening control is achieved, and the microfluid is transported to the outlet of the microchannel through the microchannel.

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