Capacitive sensor integrated unit, integrated array and method for detecting conductive droplets

Abstract

The present invention discloses a capacitive sensor integrated unit, integrated array and method for detecting conductive droplets, which are applied to digital microfluidic systems, wherein the capacitive sensor integrated unit comprises: a capacitive sensor; in the capacitive sensor, a first electrode is deposited and patterned on a portion of the upper surface of a substrate; a first insulating material covers the substrate and the first electrode; a second electrode is deposited and patterned on a portion of the upper surface of the first insulating material, and the first electrode and the second electrode do not overlap in the horizontal direction; wherein the first electrode, the first insulating material and the second electrode form a detection capacitor; the detection capacitance value when there is a conductive droplet on the capacitive sensor is greater than the detection capacitance value when there is no conductive droplet on the capacitive sensor. The present invention can judge the presence of a droplet by the capacitance of the capacitive sensor, and can be applied to a digital microfluidic system with discrete electrodes in a two-dimensional plane to achieve real-time monitoring of the droplet position.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and in particular to a capacitive sensor integrated unit, an integrated array and a method for detecting conductive droplets. Background Art

[0002] A digital microfluidic system is a system based on microfluidics technology and digital control. It can independently control the movement of individual droplets for precise manipulation by programming the electrical signal output of an electrode array, automating experiments and effectively reducing time and material costs. In microfluidic applications such as drug discovery, quantitative analysis, and biochemical reactions, liquids need to be precisely controlled for precise processing. In the prior art, the position of droplets in the array can be monitored in real time with the help of an optical microscope, but this method cannot automatically and accurately feedback the position distribution of droplets. For droplet detection within the system, the prior art mainly uses a microfluidic system based on the dielectric wetting principle, such as Figure 1 As shown, the upper cover, droplets or droplet movement space without droplets, and electrodes can form a capacitor, and the size of the capacitor can characterize the presence of droplets to achieve droplet detection. However, dielectric wetting technology requires a higher voltage, an upper cover, and a high-quality dielectric layer. For digital microfluidic systems without an upper cover and only discrete electrodes on a two-dimensional plane, such as Figure 2 The microfluidic system based on the electro-dewetting technology shown in the figure currently has no suitable droplet detection device. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a capacitive sensor integrated unit, an integrated array and a method for detecting conductive droplets. By introducing a lower electrode and a dielectric, the conductive droplets are used as the capacitive sensor electrode, so that the presence of the droplets can be determined according to the capacitance of the capacitive sensor. It can be applied to a microfluidic system based on electrodewetting technology to realize droplet detection.

[0004] The present invention provides a capacitive sensor integrated unit for detecting conductive droplets, which is applied to a digital microfluidic system. The digital microfluidic system uses an electrode array to precisely manipulate the movement of a trace amount of liquid using electrical signals;

[0005] The capacitive sensor integrated unit comprises: a capacitive sensor; the capacitive sensor comprises a substrate 1, a first electrode 4, a first insulating material 5 and a second electrode 6; the second electrode 6 is an electrode of the digital microfluidic system;

[0006] In the capacitive sensor, the first electrode 4 is deposited and patterned on a portion of the upper surface of the substrate 1; the first insulating material 5 covers the substrate 1 and the first electrode 4; the second electrode 6 is deposited and patterned on a portion of the upper surface of the first insulating material 5, and the first electrode 4 and the second electrode 6 do not overlap in the horizontal direction; wherein the first electrode 4, the first insulating material 5 and the second electrode 6 form a detection capacitor; and the detection capacitance value when there is a conductive droplet 8 on the capacitive sensor is greater than the detection capacitance value when there is no conductive droplet 8 on the capacitive sensor.

[0007] As an improved solution of the above solution, the capacitive sensor integrated unit further includes: a capacitance reading circuit; the capacitance reading circuit is electrically connected to the first electrode 4 of the capacitive sensor, and the second electrode 6 is grounded, and is used to read the capacitance value of the capacitive sensor to detect the conductive droplet;

[0008] The capacitance reading circuit includes any one of a capacitance reading circuit relying on frequency modulation of an oscillator, a capacitance reading circuit utilizing impedance voltage division, a capacitance reading circuit utilizing a charge amplifier, and a capacitance reading circuit utilizing charge charging and discharging time.

[0009] As another improved solution of the above solution, the capacitive sensor integrated unit further includes: a capacitance reading circuit using charge and discharge time; the capacitance reading circuit is electrically connected to the first electrode 4 of the capacitive sensor, and the second electrode 6 is grounded, and is used to read the capacitance value of the capacitive sensor to detect conductive droplets;

[0010] The capacitance reading circuit includes: a first load, a first transistor T1, a second load and a second transistor T2;

[0011] Among them, the first port of the first load is electrically connected to the positive power supply wire, the second port of the first load is electrically connected to one end of the source and drain of the first transistor T1, the gate of the second transistor T2 and the first electrode of the capacitance sensor; the other end of the source and drain of the first transistor T1 is electrically connected to the negative power supply wire; the input end of the capacitance reading circuit is electrically connected to the gate of the first transistor T1; the first port of the second load is electrically connected to one end of the source and drain of the second transistor T2 and the output end of the capacitance reading circuit, and the second port of the second load is electrically connected to the negative power supply wire; the other end of the source and drain of the second transistor T2 is electrically connected to the positive power supply wire.

[0012] Further, the first load includes: a resistor, or a common diode, or a diode formed by a transistor having a gate connected to a source and a drain;

[0013] If the first load is a diode, the anode of the diode is connected to the first port of the first load, and the cathode of the diode is connected to the second port of the first load.

[0014] Further, the second load includes: a resistor, or a common diode, or a diode formed by a transistor whose gate is connected to one of a source and a drain;

[0015] If the second load is a diode, the anode of the diode is connected to the first port of the second load, and the cathode of the diode is connected to the second port of the second load.

[0016] Furthermore, on the substrate 1 of the capacitive sensor integrated unit, there are arranged from bottom to top a semiconductor material, a second insulating material 3, a first conductive material, the first insulating material 5, a second conductive material, and a third insulating material;

[0017] The semiconductor material is deposited and patterned on a portion of the upper surface of the substrate 1, a portion of which is used as the source, drain and channel 2B of the first transistor T1, and another portion of which is used as the source, drain and channel 2A of the second transistor T2;

[0018] The second insulating material 3 covers the substrate 1 and the semiconductor material, a part of which serves as the gate dielectric of the first transistor T1, and another part of which serves as the gate dielectric of the second transistor T2;

[0019] The first conductive material is deposited and patterned on a portion of the upper surface of the second insulating material 3, a portion of which serves as the gate 4B of the first transistor T1, another portion of which serves as the gate 4A of the second transistor T2, and another portion of which serves as the first electrode 4 of the capacitive sensor;

[0020] The first insulating material 5 covers the first conductive material and the second insulating material 3;

[0021] The second conductive material is deposited and patterned on a portion of the upper surface of the first insulating material 5; wherein the second conductive material is divided into five parts: the first part is electrically connected to the source and drain of the first transistor T1, and serves as the source and drain electrode 6D of the first transistor T1; the second part is a first connecting unit 6C, which is used to connect the source and drain of the first transistor T1 and the first electrode 4 of the capacitive sensor; the third part is electrically connected to the source and drain of the second transistor T2, and serves as the source and drain electrode 6A of the second transistor T2; the fourth part is a second connecting unit 6B, which is used to connect the gate 4A of the second transistor T2 and the first electrode 4 of the capacitive sensor; and the fifth part serves as the second electrode 6 of the capacitive sensor;

[0022] The third insulating material 7 is deposited and patterned to cover the first transistor T1 and the second transistor T2 .

[0023] Furthermore, the capacitive sensor integrated unit also includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode 6 and is used to control the output level of the second electrode 6, thereby controlling the flow of the conductive droplet.

[0024] The present invention also provides an integrated array for detecting conductive droplets, which is applied to a digital microfluidic system and includes a plurality of capacitive sensor integrated units as described above arranged in an array.

[0025] As an improvement of the above-mentioned capacitive sensor integrated unit, the capacitive sensor integrated unit is an active integrated unit, and the capacitive reading circuit is an addressable capacitive reading circuit; the active integrated unit also includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode, and is used to control the output level of the second electrode, thereby controlling the flow of conductive droplets; the pixel circuit is an active pixel circuit with three ports; the three ports of the active pixel circuit include a row selection terminal, a column data terminal and an output terminal, and the output terminal is electrically connected to the second electrode.

[0026] The present invention also provides another integrated array for detecting conductive droplets, which is applied to a digital microfluidic system and includes a plurality of the above active integrated units arranged in an array;

[0027] The integrated array is an active integrated array, and the active integrated array comprises: the active integrated unit, the electrode scanning selection line placed horizontally, the electrode data line placed vertically, the capacitor scanning selection line placed horizontally and the capacitor data output line placed vertically;

[0028] Among them, the electrode scanning selection line is electrically connected to the row selection end of the active pixel circuit; the electrode data line is electrically connected to the column data end of the active pixel circuit; the capacitor scanning selection line is electrically connected to the input end of the addressable capacitor reading circuit; the capacitor data output line is electrically connected to the output end of the addressable capacitor reading circuit.

[0029] An embodiment of the present invention further provides a method for detecting conductive droplets, which is applied to the above integrated array for detecting conductive droplets. The method includes:

[0030] Initialize each integrated unit of the integrated array to ground the second electrode 6;

[0031] Reading the capacitance values ​​of the integrated units one by one through a capacitance reading circuit;

[0032] Determining whether the capacitance value of the integrated unit is greater than a preset value one by one;

[0033] If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit;

[0034] If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

[0035] The embodiment of the present invention further provides another method for detecting conductive droplets, which is applied to the above-mentioned integrated array for detecting conductive droplets, wherein the integrated array is an active integrated array, and the method comprises:

[0036] The second electrode 6 of each integrated unit in the integrated array is selected row by row through the electrode scanning selection lines arranged horizontally, and each integrated unit is initialized column by column through the electrode data lines arranged vertically, so that the second electrode 6 is grounded;

[0037] Selecting the capacitance of each integrated unit in the integrated array row by row through the transversely placed capacitance scanning selection lines, and then reading the capacitance value of the integrated unit column by column through the capacitance data output lines;

[0038] Determining whether the capacitance value of the integrated unit is greater than a preset value one by one;

[0039] If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit;

[0040] If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

[0041] Furthermore, the method further comprises:

[0042] Calculating the coverage area of ​​the conductive droplet according to the position of the conductive droplet;

[0043] Obtaining a droplet contact angle of the conductive droplet;

[0044] The volume of the conductive droplet is calculated according to the droplet contact angle and the coverage area of ​​the conductive droplet.

[0045] Compared with the prior art, the beneficial effects of the capacitive sensor integrated unit, integrated array and method for detecting conductive droplets provided by the present invention are: by digging a hole in the middle of the electrode of the digital microfluidic system and introducing a conductive material and a dielectric thereunder, the conductive droplet, the electrode material, the dielectric and the electrode of the digital microfluidic system form a capacitive sensor, which can detect the presence of the conductive droplet by the size of the capacitance; by integrating the integrated unit composed of the capacitive sensor and the capacitive reading circuit with the pixel circuit of the digital microfluidic system, the presence of the droplet can be detected; by forming the above-mentioned integrated units into an array, the position of the target droplet in the digital microfluidic system can be detected and monitored. By forming the active integrated units of the capacitive sensor into an array, the signal noise interference caused by the wiring layout can be reduced, which is conducive to large-scale operation, improves portability, and can read the droplet position more quickly and accurately. The embodiments of the present invention can be applied not only to structures with upper cover plates based on the dielectric wetting principle, but also to digital microfluidic systems with discrete electrodes only on a two-dimensional plane. They are suitable for microfluidic systems based on electro-dewetting technology, which can detect the presence of droplets in real time and monitor the position of droplets in real time, which is conducive to automatic and accurate feedback of the position distribution of droplets. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the structure of a microfluidic system based on the dielectric wetting principle;

[0047] Figure 2 It is a schematic diagram of the structure of a microfluidic system based on the principle of electrodewetting;

[0048] Figure 3 is a schematic diagram of a cross-sectional structure of a capacitive sensor provided by an embodiment of the present invention;

[0049] Figure 4 It is a schematic diagram of detecting capacitance of a capacitive sensor provided by an embodiment of the present invention when there are conductive droplets;

[0050] Figure 5 is a top view of a capacitive sensor provided by an embodiment of the present invention;

[0051] Figure 6 is a circuit diagram of a capacitance reading circuit provided by an embodiment of the present invention;

[0052] Figure 7 is a schematic cross-sectional structure diagram of a capacitive sensor integrated unit provided by an embodiment of the present invention;

[0053] Figure 8 It is a schematic diagram of detecting capacitance of a capacitive sensor integrated unit provided by an embodiment of the present invention when there are conductive droplets;

[0054] Fig. 9is a schematic structural diagram of an integrated array for detecting conductive droplets provided by an embodiment of the present invention;

[0055] Fig.10 is a schematic structural diagram of an active integrated array for detecting conductive droplets provided by an embodiment of the present invention;

[0056] Fig.11 is a circuit diagram of an active integrated array for detecting conductive droplets provided by an embodiment of the present invention;

[0057] The reference numerals are as follows:

[0058] 1. substrate; 3. third insulating material; 4. first electrode; 5. first insulating material; 6. second electrode; 8. conductive droplet; 2A. source, drain and channel of second transistor; 2B. source, drain and channel of first transistor; 4A. gate of second transistor; 4B. gate of first transistor; 6A. source and drain electrode of second transistor; 6B. first connecting unit; 6C. second connecting unit; 6D. source and drain electrode of first transistor; 7. third insulating material; 1.1A. first row capacitor scanning selection line; 1.1B. first row electrode scanning selection line; 1.2A. second row Capacitor scanning selection line; 1.2B, second row electrode scanning selection line; 3.1A, first column electrode data line; 3.1B, first column capacitor data output line; 3.2A, second column electrode data line; 3.2B, second column capacitor data output line; 5A, pixel point P(1,1) connected to the contact opening point of the capacitor scanning selection line; 5B, pixel point P(1,2) connected to the contact opening point of the capacitor scanning selection line; 5C, pixel point P(2,1) connected to the contact opening point of the capacitor scanning selection line; 5D, pixel point P(2,2) connected to the contact opening point of the capacitor scanning selection line. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The embodiment of the present invention provides a capacitive sensor integrated unit for detecting conductive droplets, which is applied to a digital microfluidic system. The digital microfluidic system uses an electrode array to precisely manipulate the movement of a trace amount of liquid using electrical signals;

[0061] The capacitive sensor integrated unit comprises: a capacitive sensor; the capacitive sensor comprises a substrate 1, a first electrode 4, a first insulating material 5 and a second electrode 6; the second electrode 6 is an electrode of the digital microfluidic system;

[0062] In the capacitive sensor, the first electrode 4 is deposited and patterned on a portion of the upper surface of the substrate 1; the first insulating material 5 covers the substrate 1 and the first electrode 4; the second electrode 6 is deposited and patterned on a portion of the upper surface of the first insulating material 5, and the first electrode 4 and the second electrode 6 do not overlap in the horizontal direction; wherein the first electrode 4, the first insulating material 5 and the second electrode 6 form a detection capacitor; and the detection capacitance value when there is a conductive droplet 8 on the capacitive sensor is greater than the detection capacitance value when there is no conductive droplet 8 on the capacitive sensor.

[0063] Specifically, the capacitive sensor integrated unit is applied to the digital microfluidic system, which can precisely manipulate the movement of trace amounts of liquid by utilizing the electrical signals of an electrode array composed of capacitive sensors, wherein the capacitive sensor integrated unit can detect conductive droplets by the capacitance of the capacitive sensor. Figure 3 , Figure 3 : is a schematic diagram of the cross-sectional structure of a capacitive sensor provided by an embodiment of the present invention. An implementation scheme of the capacitive sensor is: deposit a layer of conductive material on the surface of the substrate material, and this layer of conductive material is patterned as the bottom electrode of the detection capacitor, that is, the first electrode 4; then deposit a layer of first insulating material 5, covering the substrate 1 and the first electrode 4, as a part of the detection capacitor dielectric; finally, deposit another layer of conductive material as the electrode of the digital microfluidic system, that is, the second electrode 6, and the second electrode 6 does not overlap with the first electrode 4 in the horizontal direction. Please refer to Figure 3 and Figure 4 , Figure 4 It is a schematic diagram of detecting capacitance of a capacitive sensor provided by an embodiment of the present invention when there are conductive droplets. Figure 3 As shown, when there is no droplet, there is edge capacitance between the first electrode 4 and the surrounding second electrode 6, and the capacitance of the capacitive sensor can be ignored at this time; Figure 4 As shown, when there is a droplet, the conductive droplet 8 contacts the second electrode 6, so that the conductive droplet 8 serves as a capacitor plate, the first insulating material 5 serves as a dielectric of the capacitor, and the first electrode 4 serves as another capacitor plate. At this time, the second electrode 6 forms a non-negligible capacitance through the conductive droplet 8, the first insulating material 5 and the first electrode 4. Therefore, when there is a droplet, the capacitance between the second electrode 6 and the first electrode 4 is large; when there is no droplet, the capacitance between the second electrode 6 and the first electrode 4 is small. The embodiment of the present invention can detect whether there is a conductive droplet by reading the capacitance value of the capacitive sensor.

[0064] Furthermore, in the capacitive sensor, there are three possible distributions of the first electrode 4 and the second electrode 6, see Figure 5 , Figure 5 1 is a top view of a capacitive sensor provided by an embodiment of the present invention, wherein FIG. (a) shows a case where the first electrode 4 is distributed at the corner of the second electrode 6, FIG. (b) shows a case where the first electrode 4 is distributed at the edge of the second electrode 6, and FIG. (c) shows a case where the first electrode 4 is distributed in the middle of the second electrode 6. Figure 3 The structural diagram shown is Figure 5 The dotted line portion corresponds to the cross-sectional view.

[0065] The embodiment of the present invention introduces an insulating layer under the electrode of the digital microfluidic system, digs a hole at a certain position on the electrode to expose the insulating layer, and places a conductive material smaller than the hole size under the insulating layer at the hollowed-out position as the first electrode, so that when there are droplets, the electrode forms a large capacitor through the conductive droplets, and when there are no droplets, the capacitance of the capacitive sensor can be ignored. Therefore, when the capacitive sensor is applied to a microfluidic system based on electrodewetting technology, droplet detection of the microfluidic system can be realized.

[0066] As one of the optional embodiments, the capacitive sensor integrated unit further includes: a capacitance reading circuit; the capacitance reading circuit is electrically connected to the first electrode 4 of the capacitive sensor, and the second electrode 6 is grounded, and is used to read the capacitance value of the capacitive sensor to detect the conductive droplet;

[0067] The capacitance reading circuit includes any one of a capacitance reading circuit relying on frequency modulation of an oscillator, a capacitance reading circuit utilizing impedance voltage division, a capacitance reading circuit utilizing a charge amplifier, and a capacitance reading circuit utilizing charge charging and discharging time.

[0068] Specifically, the capacitance sensor integrated unit is composed of a capacitance sensor and a capacitance reading circuit for detecting the capacitance of the capacitance sensor, wherein the first electrode of the capacitance sensor is connected to the capacitance reading circuit, and the second electrode is grounded. The capacitance reading circuit includes but is not limited to frequency modulation of an oscillator, impedance voltage divider, charge amplifier, etc.

[0069] As one of the optional embodiments, the capacitive sensor integrated unit further includes: a capacitance reading circuit using charge and discharge time; the capacitance reading circuit is electrically connected to the first electrode 4 of the capacitive sensor, and the second electrode 6 is grounded, and is used to read the capacitance value of the capacitive sensor to detect conductive droplets;

[0070] The capacitance reading circuit includes: a first load, a first transistor T1, a second load and a second transistor T2;

[0071] The first port of the first load is connected to the positive power supply wire L DDThe second port of the first load is electrically connected to the source and drain of the first transistor T1, the gate of the second transistor T2 and the first electrode of the capacitive sensor; the other source and drain of the first transistor T1 is electrically connected to the negative power supply wire L SS Electrical connection; the input terminal L of the capacitance reading circuit in The first port of the second load is electrically connected to the gate of the first transistor T1; the first port of the second load is electrically connected to the source and drain of the second transistor T2 and the output terminal L of the capacitance reading circuit out The second port of the second load is electrically connected to the negative power supply wire L SS The other end of the source and drain of the second transistor T2 is electrically connected to the positive power supply wire L DD Electrical connection.

[0072] See also Figure 6 , Figure 6 is a circuit diagram of a capacitance reading circuit provided by an embodiment of the present invention. in is the input voltage, V Out is the output voltage, V C is the voltage of the first electrode of the capacitive sensor C, V DD Represents the positive power supply voltage, V SS The first transistor T1 is a transistor for controlling the charging and discharging of the circuit. The capacitance reading circuit detects the voltage V of the first electrode of the capacitance sensor C within a certain discharge time. C To determine the capacitance, the droplets are detected based on the capacitance.

[0073] Furthermore, in the droplet detection process, for the capacitance reading circuit, in the initial state, the first transistor T1 is turned off, and the voltage V C Connect the positive power supply V through the first load DD , charge the capacitive sensor C to V DD At this time, the resistance of the second transistor T2 is the minimum value in the working state of the test circuit, the voltage division of the second transistor T2 is the minimum value in the working state, and the output voltage V Out is the maximum value in the working state; in the test state, the first transistor T1 is turned on, and the voltage V on the capacitive sensor C C The voltage V of the capacitive sensor C is discharged through the first transistor T1. C From V DD After the first transistor T1 is turned on, after a sufficiently long discharge time, the voltage V on the capacitive sensor C C It can be discharged to the series voltage divided V1 of the resistance of the first transistor T1 when it is turned on and the resistance of the first load; when the turn-on time t of the first transistor T1 is less than the discharge time constant τ, at time t, the voltage V C The output is Since the capacitance value of the capacitive sensor C is larger when there is a droplet than when there is no droplet, at time t, the voltage V C When there is a droplet, the resistance of the second transistor T2 is smaller than when there is no droplet. The partial pressure of the second transistor T2 is smaller when there is a droplet than when there is no droplet. The output voltage V Out When there is a droplet, it is larger than when there is no droplet; therefore, the voltage V can be read according to the capacitance reading circuit Out The voltage at time t (t<τ) is used to determine the presence of a droplet.

[0074] As one of the optional embodiments, the first load includes: a resistor, or a common diode, or a diode formed by a transistor whose gate is connected to a source and a drain;

[0075] If the first load is a diode, the anode of the diode is connected to the first port of the first load, and the cathode of the diode is connected to the second port of the first load.

[0076] As one of the optional embodiments, the second load includes: a resistor, or a common diode, or a diode formed by a transistor whose gate is connected to a source and a drain;

[0077] If the second load is a diode, the anode of the diode is connected to the first port of the second load, and the cathode of the diode is connected to the second port of the second load.

[0078] Furthermore, in the capacitance sensor integrated unit of the embodiment of the present invention, the capacitance sensor, the first transistor T1 and the second transistor T2 are integrated.

[0079] As one of the optional embodiments, on the substrate 1 of the capacitive sensor integrated unit, semiconductor material, second insulating material 3, first conductive material, first insulating material 5, second conductive material, and third insulating material are arranged from bottom to top;

[0080] The semiconductor material is deposited and patterned on a portion of the upper surface of the substrate 1, a portion of which is used as the source, drain and channel 2B of the first transistor T1, and another portion of which is used as the source, drain and channel 2A of the second transistor T2;

[0081] The second insulating material 3 covers the substrate 1 and the semiconductor material, a part of which serves as the gate dielectric of the first transistor T1, and another part of which serves as the gate dielectric of the second transistor T2;

[0082] The first conductive material is deposited and patterned on a portion of the upper surface of the second insulating material 3, a portion of which serves as the gate 4B of the first transistor T1, another portion of which serves as the gate 4A of the second transistor T2, and another portion of which serves as the first electrode 4 of the capacitive sensor;

[0083] The first insulating material 5 covers the first conductive material and the second insulating material 3;

[0084] The second conductive material is deposited and patterned on a portion of the upper surface of the first insulating material 5; wherein the second conductive material is divided into five parts: the first part is electrically connected to the source and drain of the first transistor T1, and serves as the source and drain electrode 6D of the first transistor T1; the second part is a first connecting unit 6C, which is used to connect the source and drain of the first transistor T1 and the first electrode 4 of the capacitive sensor; the third part is electrically connected to the source and drain of the second transistor T2, and serves as the source and drain electrode 6A of the second transistor T2; the fourth part is a second connecting unit 6B, which is used to connect the gate 4A of the second transistor T2 and the first electrode 4 of the capacitive sensor; and the fifth part serves as the second electrode 6 of the capacitive sensor;

[0085] The third insulating material 7 is deposited and patterned to cover the first transistor T1 and the second transistor T2 .

[0086] For details, please refer to Figure 7 , Figure 7 1 is a schematic diagram of a cross-sectional structure of a capacitive sensor integrated unit provided by an embodiment of the present invention. The implementation method of the capacitive sensor integrated unit is as follows:

[0087] First, a layer of semiconductor material is deposited on the substrate 1, wherein the semiconductor material is divided into two parts, one part of the semiconductor material serves as the source, drain and channel 2A of the second transistor, and the other part of the semiconductor material serves as the source, drain and channel 2B of the first transistor; wherein the corresponding semiconductor material portion below the transistor gate (i.e., the gate 4A of the second transistor, the gate 4B of the first transistor) is the channel, and the portion not covered by the gate is treated by doping or the like to reduce the resistivity of the portion, serving as the source and drain of the transistor, and the portion is connected to metal (i.e., conductive material) and powered through the metal.

[0088] Then, a layer of insulating material, namely, the third insulating material 3, is deposited on the substrate 1 and the semiconductor material as the gate dielectric of the two transistors to isolate the electrode material and the active layer. Then, a layer of conductive material, namely, the first conductive material, is deposited and patterned on the third insulating material 3. The first conductive material is divided into three parts, one of which is used as the first electrode 4 of the capacitive sensor; another part is located directly above the source, drain and channel 2A of the second transistor and serves as the top gate 4A of the second transistor; and another part is located directly above the source, drain and channel 2B of the first transistor and serves as the top gate 4B of the first transistor.

[0089] Then, a layer of insulating material, i.e., the first insulating material 5, is covered to form a new insulating layer. Then, holes are opened above the semiconductor material and the first conductive material, respectively, and a layer of new conductive material, i.e., the second conductive material, is deposited and patterned after the holes are opened. The second conductive material is divided into five parts. In the second conductive material, the first part is connected to the source and drain of the first transistor and one end of the source and drain in the channel 2B through the contact hole, serving as the source and drain electrode 6D of the first transistor. The second part is the first connecting unit 6C, which is connected to the first electrode 4, the source and drain of the first transistor and the other end of the source and drain in the channel 2B through the contact hole, so that the source and drain of the first transistor are electrically connected to the first electrode 4 of the capacitive sensor. The third part is connected to the source and drain of the second transistor and one end of the source and drain in the channel 2A through the contact hole, serving as the source and drain electrode 6A of the second transistor. The fourth part is the second connecting unit 6B, which is connected to the top gate 4A of the second transistor and the first electrode 4 of the capacitive sensor through the contact hole, so that the gate 4A of the second transistor is electrically connected to the first electrode 4 of the capacitive sensor. The fifth part serves as the second electrode 6 of the capacitive sensor.

[0090] Finally, a layer of insulating material, i.e., a third insulating material 7, is deposited and patterned on the second conductive material. The third insulating material 7 is divided into two parts, one part covers the source-drain electrode 6A of the second transistor and the second connecting unit 6B, and the other part covers the first connecting unit 6C and the source-drain electrode 6D of the first transistor, and exposes the second electrode 6, thereby realizing the integration of the capacitive sensor, the first transistor T1, and the second transistor T2.

[0091] For further information, see Figure 8 , Figure 8 Schematic diagram of detection capacitance of a capacitive sensor integrated unit provided by an embodiment of the present invention when there is a conductive droplet. When there is a conductive droplet 8 on the capacitive sensor integrated unit, the conductive droplet 8, the first electrode 4, the second electrode 6 and the first insulating material 5 form a detection capacitor, the capacitance of which cannot be ignored, so the presence of the conductive droplet can be determined by reading the size of the detection capacitor.

[0092] As one of the optional embodiments, the capacitive sensor integrated unit further includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode 6, and is used to control the output level of the second electrode 6, thereby controlling the flow of the conductive droplet.

[0093] Specifically, the capacitive sensor integrated unit is composed of a capacitive sensor, a capacitive reading circuit for detecting the capacitance of the capacitive sensor, and a pixel circuit of a digital microfluidic system.

[0094] Accordingly, an embodiment of the present invention provides an integrated array for detecting conductive droplets, which is applied to a digital microfluidic system, and includes a plurality of capacitive sensor integrated units arranged in an array as described in any one of the above. The specific structure, implementation method, working principle and technical effect of the capacitive sensor integrated unit are the same as those of the capacitive sensor integrated unit for detecting conductive droplets in the above embodiment, and will not be described in detail here.

[0095] Specifically, in order to realize the movement of droplets in a two-dimensional plane, the electrically driven digital microfluidic system requires a substrate composed of a large number of discrete electrodes to control the flow of droplets. The embodiment of the present invention is described by taking a 2×2 array as an example.

[0096] See also Fig. 9 , is a schematic diagram of the structure of an integrated array for detecting conductive droplets provided by an embodiment of the present invention, wherein the capacitive sensor integrated unit is Figure 5 (a) is integrated in a 2×2 array. It should be noted that the integrated array in the embodiment of the present invention may be an m×n (m≥2, n≥2) array. Specifically, Fig. 9 The integrated array shown includes 4 capacitive sensor integrated units, each of which includes a capacitive sensor, a capacitive reading circuit, and a pixel circuit of a digital microfluidic system. Among them, the first pixel circuit controls the second electrode of the first row and the first column to be grounded, the first capacitive reading circuit reads the capacitance of the capacitive sensor of the first row and the first column, and judges whether the droplet is in the first row and the first column according to the capacitance. Correspondingly, the second pixel circuit controls the second electrode of the first row and the second column to be grounded, and the second capacitive reading circuit reads the capacitance of the capacitive sensor of the first row and the second column; the third pixel circuit controls the second electrode of the second row and the first column to be grounded, and the third capacitive reading circuit reads the capacitance of the capacitive sensor of the second row and the first column; the fourth pixel circuit controls the second electrode of the second row and the second column to be grounded, and the fourth capacitive reading circuit reads the capacitance of the capacitive sensor of the second row and the second column. Similarly, according to the capacitance value read, the position of the droplet can be judged.

[0097] Accordingly, an embodiment of the present invention provides a method for detecting conductive droplets, which is applied to the above-mentioned integrated array for detecting conductive droplets, and the method includes:

[0098] Initialize each integrated unit of the integrated array to ground the second electrode 6;

[0099] Reading the capacitance values ​​of the integrated units one by one through a capacitance reading circuit;

[0100] Determining whether the capacitance value of the integrated unit is greater than a preset value one by one;

[0101] If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit;

[0102] If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

[0103] The specific structure, implementation method, working principle and technical effect of the integrated array are the same as those of the integrated array for detecting conductive droplets in the above embodiment, and will not be described in detail here. The embodiment of the present invention can monitor the position of the target droplet by detecting the capacitance of each integrated unit in the integrated array and judging the position of the droplet by the capacitance, which is conducive to automatic and accurate feedback of the position distribution of the droplet.

[0104] As an optional embodiment of the above-mentioned capacitive sensor integrated unit, the capacitive sensor integrated unit is an active integrated unit, and the capacitive reading circuit is an addressable capacitive reading circuit; the active integrated unit also includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode, and is used to control the output level of the second electrode, thereby controlling the flow of conductive droplets; the pixel circuit is an active pixel circuit with three ports; the three ports of the active pixel circuit include a row selection terminal, a column data terminal and an output terminal, and the output terminal is electrically connected to the second electrode.

[0105] Accordingly, an embodiment of the present invention further provides another integrated array for detecting conductive droplets, which is applied to a digital microfluidic system and includes a plurality of the above active integrated units arranged in an array;

[0106] The integrated array is an active integrated array, and the active integrated array comprises: the active integrated unit, the electrode scanning selection line placed horizontally, the electrode data line placed vertically, the capacitor scanning selection line placed horizontally and the capacitor data output line placed vertically;

[0107] Among them, the electrode scanning selection line is electrically connected to the row selection end of the active pixel circuit; the electrode data line is electrically connected to the column data end of the active pixel circuit; the capacitor scanning selection line is electrically connected to the input end of the addressable capacitor reading circuit; the capacitor data output line is electrically connected to the output end of the addressable capacitor reading circuit.

[0108] Among them, the specific structure, implementation method, working principle and technical effect achieved by the active integrated unit are the same as those of the active integrated unit in the above embodiment, and will not be repeated here.

[0109] For details, please refer to Fig.10 , Fig.10 It is a schematic diagram of the structure of an active integrated array for detecting conductive droplets provided by an embodiment of the present invention. Fig.10 Taking a 2×2 array as an example, 1.1A and 1.2A are the capacitance scanning selection lines of the first row and the second row, respectively, 1.1B and 1.2B are the electrode scanning selection lines of the first row and the second row, respectively, 3.1A and 3.2A are the electrode data lines of the first column and the second column, respectively, 3.1B and 3.2B are the capacitance data output lines of the first column and the second column, respectively, 5A, 5B, 5C and 5D are the contact opening points connecting the pixel points P(1,1), P(1,2), P(2,1) and P(2,2) to the capacitance scanning selection lines, respectively.

[0110] The embodiments of the present invention rely on the active matrix for addressing control in the digital microfluidic system, which can significantly reduce the number of control lines. The capacitive sensor is integrated in the pixel of the active matrix, and the addressable capacitive reading circuit integrated in the pixel can be used to determine the capacitance to achieve droplet detection in the digital microfluidic system.

[0111] It should be noted that the electrode scanning selection lines, the electrode data lines, the capacitor scanning selection lines and the capacitor data output lines may be placed horizontally or vertically.

[0112] For further information, see Fig.11 , Fig.11 This is a circuit diagram of an active integrated array for detecting conductive droplets provided by an embodiment of the present invention, showing a 2×2 addressable array integrated with a capacitive sensor, an addressable capacitance reading circuit, and an active pixel circuit, which senses and outputs the capacitance of each pixel point to determine the location of the conductive droplet. SCN1 With L SCN2 The first and second row of electrodes scan the selection line, L DT1 With L DT2 The first and second columns of electrode data lines, L in1 With L in2 The first and second rows of capacitance scanning selection lines, L Out1 With L Out2 The first and second columns are capacitor data output lines.

[0113] Specifically, the addressable circuit uses the first transistor T1 as the discharge control and also as the addressing transistor to read the capacitance of each pixel point. SCN1 Set to the turn-on voltage, V SCN2 When set to shutdown voltage, the voltage V DT1 and V DT2 are applied to the second electrodes of the pixel points P(1,1) and P(1,2) respectively; when V SCN1 Set to shutdown voltage, V SCN2 When set to the start voltage, the voltage V DT1 and V DT2 The voltage V is applied to the second electrodes of the pixels P(2,1) and P(2,2) respectively. After the droplet moves to the target pixel, the circuit for measuring the droplet at a certain pixel is turned on. SCN1 Set to the turn-on voltage, V SCN2 When set to shutdown voltage, the voltage V DT1 =0 and V DT2 = 0 is added to the second electrodes of the capacitance sensors at the pixel points P(1, 1) and P(1, 2) respectively, so that the second electrodes of the capacitance sensors at the pixel points P(1, 1) and P(1, 2) are grounded; when V SCN1 Set to shutdown voltage, V SCN2 When set to the start voltage, the voltage V DT1 =0 and V DT2 = 0 is applied to the second electrodes of the capacitive sensors at the pixel points P(2, 1) and P(2, 2), respectively, so that the second electrodes of the capacitive sensors at the pixel points P(2, 1) and P(2, 2) are grounded. SCN1 With V SCN2 Both are set to the shutdown voltage, voltage V in2 Set to 0, the voltage V in1 Set to a pulse of duration t, where V in1 The amplitude is V DD , t is less than the discharge time constant τ = RC; at time t, according to the output voltage V Out1 and V Out2 , respectively, to determine whether there is a droplet at the pixel points P(1,1) and P(1,2); similarly, the scanning voltage V SCN1 With V SCN2 Both are set to the shutdown voltage, V in1 Set to 0, input voltage V in2 Set to a pulse of duration t, where V in2 The amplitude is V DD , t is less than the discharge time constant τ = RC; at time t, according to the output voltage V Out1 and V Out2The size of is used to determine whether there are droplets at the pixel points P(2, 1) and P(2, 2). Through the judgment results corresponding to each pixel point, the position distribution and coverage area of ​​the conductive droplets can be obtained, thereby monitoring the droplet position.

[0114] The embodiment of the present invention further provides another method for detecting conductive droplets, which is applied to the above active integrated array, and the method includes:

[0115] The second electrode 6 of each integrated unit in the integrated array is selected row by row through the electrode scanning selection lines arranged horizontally, and each integrated unit is initialized column by column through the electrode data lines arranged vertically, so that the second electrode 6 is grounded;

[0116] Selecting the capacitance of each integrated unit in the integrated array row by row through the transversely placed capacitance scanning selection lines, and then reading the capacitance value of the integrated unit column by column through the capacitance data output lines;

[0117] Determining whether the capacitance value of the integrated unit is greater than a preset value one by one;

[0118] If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit;

[0119] If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

[0120] Specifically, when the array is an active integrated array, the droplet position can be quickly and accurately detected through an addressable circuit. The specific structure, implementation method, working principle and technical effect of the active integrated array are the same as those of the active integrated array in the above embodiment, and will not be repeated here.

[0121] Furthermore, the method further comprises:

[0122] Calculating the coverage area of ​​the conductive droplet according to the position of the conductive droplet;

[0123] Obtaining a droplet contact angle of the conductive droplet;

[0124] The volume of the conductive droplet is calculated according to the droplet contact angle and the coverage area of ​​the conductive droplet.

[0125] Specifically, the embodiment of the present invention obtains the coverage area according to the position distribution of the conductive droplets, and obtains the volume of the conductive droplets from the coverage area of ​​the droplets and the contact angle of the droplets, thereby achieving precise control of the liquid content.

[0126] The beneficial effects of a capacitive sensor integrated unit, integrated array and method for detecting conductive droplets provided by an embodiment of the present invention are: by digging a hole in the middle of the electrode of the digital microfluidic system and introducing a conductive material and a dielectric thereunder, the conductive droplet, the electrode material, the dielectric and the electrode of the digital microfluidic system form a capacitive sensor, which can detect the presence of the conductive droplet by the size of the capacitance; by integrating the integrated unit composed of the capacitive sensor and the capacitive reading circuit with the pixel circuit of the digital microfluidic system, the presence of the droplet can be detected; by forming the above-mentioned integrated units into an array, the position of the target droplet in the digital microfluidic system can be detected and monitored. By forming an array of active integrated units of the capacitive sensor, the signal noise interference caused by the wiring layout can be reduced, which is conducive to large-scale operation, improves portability, and can read the droplet position more quickly and accurately. The embodiments of the present invention can be applied not only to structures with upper cover plates based on the dielectric wetting principle, but also to digital microfluidic systems with discrete electrodes only on a two-dimensional plane. They are suitable for microfluidic systems based on electro-dewetting technology, which can detect the presence of droplets in real time and monitor the position of droplets in real time, which is conducive to automatic and accurate feedback of the position distribution of droplets.

[0127] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A capacitive sensor integrated unit for detecting conductive droplets, applied to a digital microfluidic system, characterized in that: The digital microfluidic system uses an electrode array to precisely manipulate the movement of micro-amounts of liquid using electrical signals; The capacitive sensor integrated unit comprises: a capacitive sensor; the capacitive sensor comprises a substrate, a first electrode, a first insulating material and a second electrode; the second electrode is an electrode of the digital microfluidic system; In the capacitive sensor, the first electrode is deposited and patterned on a portion of the upper surface of the substrate; the first insulating material covers the substrate and the first electrode; the second electrode is deposited and patterned on a portion of the upper surface of the first insulating material, and the first electrode and the second electrode do not overlap in the horizontal direction; wherein the first electrode, the first insulating material and the second electrode form a detection capacitor; and the detection capacitance value when there is a conductive droplet on the capacitive sensor is greater than the detection capacitance value when there is no conductive droplet on the capacitive sensor; The capacitance sensor integrated unit further comprises: a capacitance reading circuit using charge and discharge time; the capacitance reading circuit is electrically connected to the first electrode of the capacitance sensor, the second electrode is grounded, and is used to read the capacitance value of the capacitance sensor to detect conductive droplets; The capacitance reading circuit includes: a first load, a first transistor, a second load and a second transistor; Among them, the first port of the first load is electrically connected to the positive power supply wire, the second port of the first load is electrically connected to one end of the source and drain of the first transistor, the gate of the second transistor and the first electrode of the capacitance sensor; the other end of the source and drain of the first transistor is electrically connected to the negative power supply wire; the input end of the capacitance reading circuit is electrically connected to the gate of the first transistor; the first port of the second load is electrically connected to one end of the source and drain of the second transistor and the output end of the capacitance reading circuit, the second port of the second load is electrically connected to the negative power supply wire; the other end of the source and drain of the second transistor is electrically connected to the positive power supply wire.

2. The capacitive sensor integrated unit for detecting conductive droplets according to claim 1, characterized in that: The first load includes: a resistor, or a common diode, or a diode formed by a transistor with a gate connected to a source and a drain; If the first load is a diode, the anode of the diode is connected to the first port of the first load, and the cathode of the diode is connected to the second port of the first load.

3. The capacitive sensor integrated unit for detecting conductive droplets according to claim 1, characterized in that: The second load includes: a resistor, or a common diode, or a diode formed by a transistor whose gate is connected to a source and a drain; If the second load is a diode, the anode of the diode is connected to the first port of the second load, and the cathode of the diode is connected to the second port of the second load.

4. The capacitive sensor integrated unit for detecting conductive droplets according to claim 1, characterized in that: On the substrate of the capacitive sensor integrated unit, a semiconductor material, a second insulating material, a first conductive material, the first insulating material, a second conductive material, and a third insulating material are arranged from bottom to top; The semiconductor material is deposited and patterned on a portion of the upper surface of the substrate, a portion of which serves as the source, drain and channel of the first transistor, and another portion of which serves as the source, drain and channel of the second transistor; The second insulating material covers the substrate and the semiconductor material, a portion of which serves as a gate dielectric of the first transistor, and another portion of which serves as a gate dielectric of the second transistor; The first conductive material is deposited and patterned on a portion of the upper surface of the second insulating material, a portion of which serves as the gate of the first transistor, another portion of which serves as the gate of the second transistor, and another portion of which serves as the first electrode of the capacitive sensor; The first insulating material covers the first conductive material and the second insulating material; The second conductive material is deposited and patterned on a portion of the upper surface of the first insulating material; wherein the second conductive material is divided into five parts: the first part is electrically connected to the source and drain of the first transistor, serving as the source and drain electrodes of the first transistor; the second part is a first connecting unit, used to connect the source and drain of the first transistor with the first electrode of the capacitive sensor; the third part is electrically connected to the source and drain of the second transistor, serving as the source and drain electrodes of the second transistor; the fourth part is a second connecting unit, used to connect the gate of the second transistor with the first electrode of the capacitive sensor; the fifth part serves as the second electrode of the capacitive sensor; The third insulating material is deposited and patterned to cover the first transistor and the second transistor.

5. The capacitive sensor integrated unit for detecting conductive droplets according to any one of claims 1 to 4, characterized in that: The capacitive sensor integrated unit further includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode and is used to control the output level of the second electrode, thereby controlling the flow of the conductive droplet.

6. The capacitive sensor integrated unit for detecting conductive droplets according to any one of claims 1 to 4, characterized in that: The capacitive sensor integrated unit is an active integrated unit, and the capacitive reading circuit is an addressable capacitive reading circuit; the active integrated unit also includes: a pixel circuit of a digital microfluidic system; the pixel circuit is electrically connected to the second electrode, and is used to control the output level of the second electrode, thereby controlling the flow of conductive droplets; the pixel circuit is an active pixel circuit with three ports; the three ports of the active pixel circuit include a row selection terminal, a column data terminal and an output terminal, and the output terminal is electrically connected to the second electrode.

7. An integrated array for detecting conductive droplets, applied to a digital microfluidic system, characterized in that: The invention comprises a plurality of capacitive sensor integrated units as claimed in any one of claims 1 to 5 arranged in an array.

8. An integrated array for detecting conductive droplets, applied to a digital microfluidic system, characterized in that: A capacitive sensor integrated unit for detecting conductive droplets according to claim 6, comprising a plurality of capacitive sensor integrated units arranged in an array, wherein the capacitive sensor integrated unit is an active integrated unit; The integrated array is an active integrated array, and the active integrated array comprises: the active integrated unit, the electrode scanning selection line placed horizontally, the electrode data line placed vertically, the capacitor scanning selection line placed horizontally and the capacitor data output line placed vertically; Among them, the electrode scanning selection line is electrically connected to the row selection end of the active pixel circuit; the electrode data line is electrically connected to the column data end of the active pixel circuit; the capacitor scanning selection line is electrically connected to the input end of the addressable capacitor reading circuit; the capacitor data output line is electrically connected to the output end of the addressable capacitor reading circuit.

9. A method for detecting conductive droplets, characterized in that: The integrated array for detecting conductive droplets as claimed in claim 7, wherein the method comprises: Initializing each integrated unit of the integrated array so that the second electrode is grounded; Reading the capacitance values ​​of the integrated units one by one through a capacitance reading circuit; Determining whether the capacitance value of the integrated unit is greater than a preset value one by one; If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit; If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

10. A method for detecting conductive droplets, characterized in that: The integrated array for detecting conductive droplets according to claim 8, wherein the integrated array is an active integrated array, and the method comprises: Select the second electrode of each integrated unit in the integrated array row by row through the electrode scanning selection lines arranged horizontally, and then initialize each integrated unit column by column through the electrode data lines arranged vertically, so that the second electrode is grounded; Selecting the capacitance of each integrated unit in the integrated array row by row through the transversely placed capacitance scanning selection lines, and then reading the capacitance value of the integrated unit column by column through the capacitance data output lines; Determining whether the capacitance value of the integrated unit is greater than a preset value one by one; If the capacitance value of the integrated unit is not greater than the preset value, it is determined that there is no conductive droplet at the position corresponding to the integrated unit; If the capacitance value of the integrated unit is greater than the preset value, it is determined that there is the conductive droplet at the position corresponding to the integrated unit, and the position of the conductive droplet is obtained.

11. The method for detecting conductive droplets according to claim 9 or 10, characterized in that: The method further comprises: Calculating the coverage area of ​​the conductive droplet according to the position of the conductive droplet; Obtaining a droplet contact angle of the conductive droplet; The volume of the conductive droplet is calculated according to the droplet contact angle and the coverage area of ​​the conductive droplet.

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