Detection method and system for connecting digital microfluidic device with DMF drive system

Abstract

The present invention relates to the field of microfluidics, and specifically to a method and system for detecting the connection between a digital microfluidic device and a DMF drive system. The detection method, system, and circuit divide the voltage value output by the digital microfluidic device, collect multiple voltage values ​​multiple times, and perform fast Fourier transform to obtain multiple modulus values ​​at points equal to the frequency of the excitation signal. A preset threshold is set according to the type, voltage, and frequency of the excitation signal, and the modulus values ​​at multiple points equal to the frequency of the excitation signal are compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system. The excitation signal and the signal for controlling droplet drive both come from the same electronic control system, which facilitates system integration and system miniaturization. Based on a digital microfluidic platform based on electrowetting, a new solution is provided for quickly determining the electrical connection between a microfluidic device and a DMF drive system.

Description

Technical Field

[0001] The present invention relates to the field of microfluidics, and in particular to a detection method and system for connecting a digital microfluidics device with a DMF drive system. Background Art

[0002] Electrowetting refers to the effect of using electric potential to control the surface tension of the liquid and solid interface, thereby changing the contact angle of the droplet. Digital microfluidic systems that utilize the electrowetting effect usually apply an electric field to a conductive electrode array, and use timed electrical signals to control the movement of microdroplets between the electrodes. In an ideal digital microfluidic system, each application of a driving potential signal will cause the target droplet to move to the corresponding electrode. However, in actual operation, the movement and exact position of the droplets are difficult to locate with the naked eye or other optical observation systems, and when manipulating multiple droplets at the same time, it is more difficult to determine whether all droplets have accurately reached the predetermined position. Accurate identification of the droplet position is particularly critical to the accuracy of manipulation and the stability of the system.

[0003] DropBot is an open-source digital microfluidics (DMF) automation system developed by the Wheeler Laboratory at the University of Toronto, Canada. This system proposes a method for automatically detecting the electrical connection between high-voltage switchboard channels and conductive electrode arrays. First, a driver board is connected to the high-voltage switchboard to be tested and the feedback circuit. The driver board applies a 10V signal to each relay in sequence while simultaneously measuring the corresponding capacitance. By checking the ratio of the measured capacitance to the expected capacitance, the electrical connection status between the high-voltage switchboard channel and the conductive electrode array can be quickly identified. However, the system's method for acquiring complex voltages is complex, and generating high-voltage, high-frequency sinusoidal excitation signals is difficult. Summary of the Invention

[0004] The embodiments of the present invention provide a method and system for detecting the connection between a digital microfluidic device and a DMF drive system, so as to at least solve the technical problem that it is relatively complicated for the existing digital microfluidic system to detect whether it is electrically connected to the drive system.

[0005] According to one embodiment of the present invention, a method for detecting the connection between a digital microfluidic device and a DMF drive system is provided, comprising the following steps:

[0006] generating an excitation signal, and inputting the excitation signal into the digital microfluidic device to generate a voltage value;

[0007] Performing voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in a digital microfluidic device;

[0008] The multiple voltage values ​​are collected multiple times and fast Fourier transform is performed to obtain the modulus values ​​of multiple points with the same frequency as the excitation signal;

[0009] A preset threshold is set according to the type, voltage and frequency of the excitation signal. The modulus values ​​of multiple points with the same frequency as the excitation signal are compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system.

[0010] Furthermore, the preset thresholds include: the modulus at the point equal to the main frequency, the maximum modulus after fast Fourier transform, the time domain amplitude corresponding to the point equal to the main frequency, the effective voltage value of the original signal, and the phase difference between the input signal and the divided voltage signal.

[0011] Furthermore, the preset threshold value = (connection module value min + No connection modulus max ) / 2; where there is a connection modulus value min Refers to the minimum value among multiple module values ​​collected when multiple electrodes are connected to the DMF drive system; no connection module value max It refers to the maximum value among multiple mode values ​​collected when multiple electrodes are not connected to the DMF drive system.

[0012] Furthermore, the detection method also includes selecting an excitation signal, and the selection of the excitation signal includes:

[0013] The module value difference between electrical connection and no electrical connection at different voltages and frequencies is calculated by a detection method, and the signal at the voltage and frequency when the module value difference is the largest is selected as the excitation signal.

[0014] Furthermore, after obtaining multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device, the detection method further includes: performing operational amplification on the multiple voltage values ​​to increase their load capacity.

[0015] Furthermore, after obtaining multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device, the detection method further includes: performing in-phase addition operation on the multiple voltage values, and performing voltage division processing again on the voltage values ​​after the in-phase addition operation.

[0016] According to another embodiment of the present invention, there is provided a detection system for connecting a digital microfluidic device to a DMF drive system, comprising: a single chip microcomputer, a channel selector, and a front-end voltage divider circuit;

[0017] The single chip microcomputer controls the channel selector to generate an excitation signal, and the excitation signal is input to the digital microfluidic device to generate a voltage value;

[0018] The front-end voltage divider circuit performs voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device;

[0019] The single-chip microcomputer collects multiple voltage values ​​multiple times and performs fast Fourier transform to obtain the modulus values ​​of multiple points with equal frequency to the excitation signal; and sets a preset threshold according to the type, voltage and frequency of the excitation signal, compares the modulus values ​​of multiple points with equal frequency to the excitation signal with the preset threshold, and determines whether each electrode in the digital microfluidic device is connected to the DMF drive system.

[0020] Furthermore, the single chip microcomputer selects and calculates the module value difference between the electrical connection and the non-electrical connection at different voltages and different frequencies, and selects the signal at the voltage and frequency when the module value difference is the largest as the excitation signal.

[0021] Furthermore, the detection system also includes:

[0022] Voltage follower: The voltage follower is connected to the front-end voltage divider circuit to perform operational amplification on multiple voltage values ​​to provide its load capacity;

[0023] a non-inverting adder connected to the output of the voltage follower and performing non-inverting addition operation on the multiple voltage values ​​after the operational amplification;

[0024] The back-end voltage divider circuit is connected to the in-phase adder to perform a voltage division process on the voltage value after the in-phase addition operation.

[0025] According to another embodiment of the present invention, a detection circuit for connecting a digital microfluidic device to a DMF drive system is provided, comprising: a dual operational amplifier and resistors R1-R7, wherein pin 1 of the dual operational amplifier is connected to pin 2 and resistor R1, pin 3 is connected to resistor R7 and then to GND, pin 4 is connected to VEE, pin 5 is connected to resistors R1 and R2, pin 6 is connected to resistor R3 and then to GND and resistor R4, pin 7 is connected to resistor R4, resistors R5 and R6 in sequence and then to GND, and pin 8 is connected to VCC; wherein a node 1 is provided between pin 3 of the dual operational amplifier and resistor R7 for connecting to a conductive cover of the digital microfluidic device; and a node 2 is provided between resistors R5 and R6 for connecting to an ADC on a single-chip microcomputer.

[0026] The detection method, system, and circuit for connecting a digital microfluidic device to a DMF drive system in an embodiment of the present invention divide the voltage output by the digital microfluidic device, collect multiple voltage values, and perform a fast Fourier transform (FFT) to obtain multiple modulus values ​​at points equal to the excitation signal frequency. A preset threshold is set according to the type, voltage, and frequency of the excitation signal. The modulus values ​​at multiple points equal to the excitation signal frequency are compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system. Both the excitation signal and the signal for controlling droplet drive come from the same electronic control system, facilitating system integration and achieving system miniaturization. Based on a digital microfluidics (DMF) platform based on electrowetting, a new solution is provided for quickly determining the electrical connection between a microfluidic device and a DMF drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 Flowchart of a detection method for connecting a digital microfluidic device to a DMF drive system according to the present invention;

[0029] Figure 2 A flow chart showing an optimal excitation signal for a detection method for connecting a digital microfluidic device to a DMF drive system according to the present invention;

[0030] Figure 3 This is a model diagram of the digital microfluidics (DMF) device in the present invention;

[0031] Figure 4 A block diagram of a detection system connecting a digital microfluidic device and a DMF drive system of the present invention;

[0032] Figure 5 This is a detection circuit diagram of the digital microfluidic device connected to the DMF drive system of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] Example 1

[0036] According to one embodiment of the present invention, a method for detecting the connection between a digital microfluidic device and a DMF drive system is provided. Figure 1 , including the following steps:

[0037] S101: Generate an excitation signal, and input the excitation signal into the digital microfluidic device to generate a voltage value;

[0038] S102: performing voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device;

[0039] S103: collecting multiple voltage values ​​and performing fast Fourier transform to obtain multiple modulus values ​​at points with the same frequency as the excitation signal;

[0040] S104: Set a preset threshold according to the type, voltage and frequency of the excitation signal, compare the modulus value at each point where the voltage value and the excitation signal frequency are equal with the preset threshold, and determine whether each electrode in the digital microfluidic device is connected to the DMF drive system.

[0041] The detection method for connecting a digital microfluidic device to a DMF drive system in an embodiment of the present invention divides the voltage output by the digital microfluidic device, collects multiple voltage value data points, and performs a fast Fourier transform (FFT) to obtain the modulus of each voltage value at the point where the excitation signal frequency is equal. A preset threshold is set according to the type, voltage, and frequency of the excitation signal. The modulus of each voltage value at the point where the excitation signal frequency is equal is compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system. The excitation signal and the signal for controlling droplet drive both come from the same electronic control system, facilitating system integration and achieving system miniaturization. Based on the electrowetting-based digital microfluidics (DMF) platform, a new solution is provided for quickly determining the electrical connection between a microfluidic device and a DMF drive system.

[0042] As a preferred technical solution, the preset thresholds include: the modulus value at the point equal to the main frequency, the maximum modulus value after fast Fourier transform, the time domain amplitude corresponding to the point equal to the main frequency, the effective voltage value of the original signal, and the phase difference between the input signal and the voltage divider signal.

[0043] As a preferred technical solution, the preset threshold value = (connection module value min + No connection modulus max ) / 2; where there is a connection modulus value min Refers to the minimum value among multiple module values ​​collected when multiple electrodes are connected to the DMF drive system; no connection module value max It refers to the maximum value among multiple mode values ​​collected when multiple electrodes are not connected to the DMF drive system.

[0044] As the preferred technical solution for the excitation signal, see Figure 2 , the detection method also includes:

[0045] S100: selection of optimal excitation signal;

[0046] The selection of the optimal excitation signal includes:

[0047] Select excitation signals at multiple voltage values ​​and multiple frequency values, calculate the module value difference between electrical connection and no electrical connection at different voltages and frequencies through a detection method, and select the signal at the voltage and frequency when the module value difference is the largest as the excitation signal.

[0048] As a preferred technical solution, after obtaining multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device, the detection method further includes: performing operational amplification on the multiple voltage values ​​to provide their load capacity.

[0049] As a preferred technical solution, after obtaining multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device, the detection method further includes: performing in-phase addition operation on the multiple voltage values, and performing voltage division processing again on the voltage values ​​after the in-phase addition operation.

[0050] Example 2

[0051] According to another embodiment of the present invention, a detection system for connecting a digital microfluidic device and a DMF drive system is provided. Figure 4 , including: single chip microcomputer, channel selector, front-end voltage divider circuit;

[0052] The single chip microcomputer controls the channel selector to send excitation signals to each electrode respectively, and the excitation signals are input to the digital microfluidic device to generate voltage values;

[0053] The front-end voltage divider circuit performs voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device;

[0054] The single-chip microcomputer collects multiple voltage values ​​multiple times and performs fast Fourier transform to obtain the modulus values ​​of multiple points with equal excitation signal frequencies; and sets a preset threshold according to the type, voltage and frequency of the excitation signal, compares the modulus values ​​of multiple points with equal excitation signal frequencies with the preset threshold, and determines whether each electrode in the digital microfluidic device is connected to the DMF drive system.

[0055] The detection system of the digital microfluidic device connected to the DMF drive system in the embodiment of the present invention divides the voltage value output by the digital microfluidic device, performs fast Fourier transform on multiple voltage value data points, obtains the modulus value of multiple excitation signal frequency equal points, sets a preset threshold value according to the type, voltage and frequency of the excitation signal, compares the modulus value of multiple excitation signal frequency equal points with the preset threshold value, and judges whether each electrode in the digital microfluidic device is connected to the DMF drive system. The excitation signal and the signal for controlling the droplet drive all come from the same electronic control system, which facilitates system integration and system miniaturization. On the digital microfluidics (DMF) platform based on electrowetting, a new solution is provided for quickly judging the electrical connection between the microfluidic device and the DMF drive system.

[0056] As a preferred technical solution, the microcontroller selects excitation signals at multiple voltage values ​​and multiple frequency values, calculates the module value difference between electrical connection and no electrical connection at different voltages and different frequencies, and selects the signal at the voltage and frequency when the module value difference is the largest as the excitation signal.

[0057] As a preferred technical solution, see Figure 4 , the detection system also includes:

[0058] Voltage follower: The voltage follower is connected to the front-end voltage divider circuit to perform operational amplification on multiple voltage values ​​to provide its load capacity;

[0059] a non-inverting adder connected to the voltage follower for performing non-inverting addition operation on the multiple voltage values ​​after the operational amplification;

[0060] The back-end voltage divider circuit is connected to the in-phase adder to perform a voltage division process on the voltage value after the in-phase addition operation.

[0061] Example 3

[0062] According to another embodiment of the present invention, a detection circuit for connecting a digital microfluidic device and a DMF drive system is provided. Figure 5, including: a dual operational amplifier and resistors R1-R7, pin 1 of the dual operational amplifier is connected to pin 2 and resistor R1, pin 3 is connected to resistor R7 and then to GND, pin 4 is connected to VEE, pin 5 is connected to resistors R1 and R2, pin 6 is connected to resistor R3 and then to GND and resistor R4, pin 7 is connected to resistor R4, resistors R5 and R6 in sequence and then to GND, and pin 8 is connected to VCC; a node 1 is set between pin 3 of the dual operational amplifier and resistor R7 for connecting to the conductive cover of the digital microfluidic device; a node 2 is set between resistors R5 and R6 for connecting to the ADC on the microcontroller.

[0063] The detection circuit of the digital microfluidic device connected to the DMF drive system in the embodiment of the present invention divides the voltage value output by the digital microfluidic device, collects multiple voltage value data points respectively multiple times, and performs fast Fourier transform to obtain the modulus values ​​of multiple points equal to the excitation signal frequency, sets a preset threshold value according to the type, voltage and frequency of the excitation signal, compares the modulus values ​​of multiple points equal to the excitation signal frequency with the preset threshold value, and judges whether each electrode in the digital microfluidic device is connected to the DMF drive system. The excitation signal and the signal for controlling the droplet drive all come from the same electronic control system, which facilitates system integration and realizes system miniaturization. On the digital microfluidics (DMF) platform based on electrowetting, a new solution is provided for quickly judging the electrical connection between the microfluidic device and the DMF drive system.

[0064] The following is a detailed description of the detection method, system and circuit for connecting the digital microfluidic device and the DMF drive system of the present invention using specific embodiments:

[0065] The digital microfluidics (DMF) device model is shown in the attached figure. Figure 3 shown. Figure 3 This is a model of a digital microfluidic device. From bottom to top, it consists of a substrate, an electrode, a dielectric layer, a hydrophobic layer, a droplet (air or liquid when there is no droplet), a hydrophobic layer, and a conductive cover.

[0066] The detection system block diagram and detection circuit schematic are shown in the attached Figure 4 、 5 As shown. The detection system mainly consists of five parts:

[0067] 1. 64-channel converter with high voltage output controlled by single chip microcomputer (attached Figure 4 The HV507 in the circuit) sends out high-voltage and high-frequency square wave signals (amplitude of 150-300 volts and frequency of 1 kHz to 100 kHz) in turn. The high-voltage and high-frequency square wave signals (excitation signals) pass through the digital DMF device and then through the resistor R7 (see attached). Figure 5 ) is grounded, and the main function of the resistor R7 is voltage division. Figure 5The schematic diagram of the detection system includes seven resistors and a dual operational amplifier. Node 1 and the ADC detection point are connected. Node 1 is connected to the conductive lid of the digital microfluidic device, and the ADC detection point is connected to the ADC on the microcontroller.

[0068] When the electrodes in a digital microfluidic device are not connected to the DMF drive system (open circuit), the impedance between the DMF drive system and the conductive cover (e.g., indium tin oxide, ITO glass) is approximately infinite. When the electrodes are fully connected to the DMF drive system, the impedance between the electrodes and the conductive cover is smaller than when they are not connected. Therefore, the voltage values ​​collected when the electrodes are connected to the DMF drive system and when they are not connected are different.

[0069] 2. The voltage after voltage division has poor load carrying capacity. In order to improve its load carrying capacity, the voltage after voltage division is passed through an operational amplifier (attached Figure 5 A voltage follower formed by the input port 6 of the dual operational amplifier of the components;

[0070] 3. The output voltage of the voltage follower has a negative voltage. In order to allow the ADC of the microcontroller to collect the voltage, the output of the voltage follower is connected to a non-inverting adder (see Appendix Figure 5 The components in the dual operational amplifier are output ports 7), and the other input of the non-inverting adder comes from the voltage on the microcontroller, such as 3.3V.

[0071] 4. The output voltage of the in-phase adder is greater than 3.3V and cannot be directly collected by the ADC. Figure 5 The resistor R7 and port 8 of the dual operational amplifier form a voltage divider circuit), which drops to less than 3.3V and is collected by the ADC on the microcontroller;

[0072] 5. ADC collects N (value range is 128-2056) data points, and performs N-point Fast Fourier Transform (FFT) inside the single chip microcomputer. FFT can also be regarded as a process of filtering noise. Because after FFT, each data point corresponds to a frequency point (increased in units of fundamental frequency), the modulus value of this data point (square root of the sum of the squares of the real part and the imaginary part) is the modulus value at the frequency value of this frequency point. In order to reduce the interference of noise, the present invention directly selects the data point that is equal to the main frequency (when there is a droplet, the modulus value of this data point is actually the point with the largest modulus value among all data points). Compare the modulus values ​​with and without electrical connection, and set a threshold value at this time. The threshold value depends on the voltage and frequency of the excitation signal. For example, when the excitation signal is a 150V, 10Khz square wave signal, and the number of electrodes is 180, the threshold value = (modulus value with connection). min + No connection modulusmax ) / 2. There is a connection modulus value min It refers to the minimum value of the 180 module values ​​collected by the detection system when all 180 electrodes are connected to the DMF drive system. The unconnected module value max refers to the maximum value of the 180 module values ​​collected by the detection system when all 180 electrodes are not connected to the DMF drive system. Therefore, this threshold is equal to the connected module value. min and unconnected modulus values max By comparing the modulus value with the set threshold, it can be determined whether the electrode is connected to the DMF drive system.

[0073] The innovative technical points of the present invention are at least:

[0074] 1. The excitation signal and the signal for controlling the droplet drive come from the same electronic control system, which facilitates system integration and realizes system miniaturization.

[0075] 2. The test solution is applicable to different types of detection signals (including but not limited to sine waves, square waves, triangle waves and other periodic signals).

[0076] 3. The system solution is compatible with square waves as detection excitation signals, which are easy to generate in electronic control systems.

[0077] 4. By detecting the module value information, the average single channel detection time can be reduced to less than 2 milliseconds.

[0078] 5. It can detect whether 180 electrodes are connected to the DMF drive system within 300 milliseconds.

[0079] 6. The circuit structure is greatly simplified and optimized compared with the existing system, requiring only 7 resistors and a dual operational amplifier, which simplifies the complex voltage acquisition method.

[0080] 7. Determine whether there is an electrical connection and the selection of the optimal excitation signal:

[0081] After selecting the waveform, it is also necessary to select the appropriate voltage and frequency. Because at different frequencies, the module values ​​of whether to be connected to the DMF drive system are different, so their module value differences are also different. In order to select the optimal voltage and frequency, the present invention selects N voltage values ​​(for example, 5, the voltages are respectively 150V, 170V, 190V, 210V, 230V), N frequency values ​​(for example, 5, respectively 10KHz, 20KHz, 30Khz, 40KHz, 50KHz). By the attached Figure 4The detection system in the embodiment of the present invention collects the module values ​​of whether the DMF drive system is connected, and calculates the module value difference of whether the DMF drive system is connected at different voltages and different frequencies. N curves are compared, and the voltage and frequency at which the module value difference of whether the DMF drive system is connected is the largest are selected as the excitation signal of the present invention.

[0082] 8. Choice of electrical connection threshold:

[0083] According to the method in the above-mentioned 2nd and 7th points, the excitation signal is selected. In order to scan a plurality of electrodes, the present invention also needs to select a suitable threshold value to judge whether to be connected with the DMF drive system. The threshold value depends on the voltage and frequency of the optimal excitation signal. For example, when the excitation signal is a 150V, 10Khz square wave signal and the number of electrodes is 180, the threshold value = (with connected module value) min + No connection modulus max ) / 2. There is a connection modulus value min It refers to the minimum value among the 180 module values ​​collected by the detection system when all 180 electrodes are connected to the DMF drive system. max It refers to the maximum value of the 180 module values ​​collected by the detection system when all 180 electrodes are not connected to the DMF drive system. Therefore, the threshold is equal to the module value when there is a connection. min and unconnected modulus values max By comparing the modulus value with the set threshold, it is possible to determine whether multiple electrodes are connected to the DMF drive system in a short time.

[0084] 9. The detection system of the present invention includes a voltage divider circuit, a voltage follower, a common-phase adder, and a voltage divider circuit. The voltage follower, the common-phase adder, and the back-end voltage divider circuit are optional. If the waveform after the voltage divider circuit at the front end has a good load capacity, the voltage follower is not required; if the voltage after the voltage divider meets 0 <V R7 <5V, then the in-phase adder and the back-end voltage divider circuit are also unnecessary; if the first two conditions are met, only one voltage divider resistor is required. In the present invention, due to the possibility that the voltage divider waveform has poor load capacity and contains negative voltage, a voltage follower, a in-phase adder, and a back-end voltage divider circuit are included.

[0085] 10. In addition to detecting whether the microfluidic device is electrically connected to the DMF drive system, the detection system proposed in the present invention can also be used to detect droplet positioning, distinguish chemical solutions of different concentrations, monitor the process of chemical reactions, etc.

[0086] 11. After collecting the voltage, perform an N-point FFT. The value range of N is 128-2048. The selection of N points should be able to collect the waveform relatively completely and detect whether the 180 electrodes are connected to the DMF drive system in a short time (for example, 300ms).

[0087] 12. After collecting the voltage, perform an N-point FFT algorithm and select the point that is equal to the main frequency as the judgment point. This can effectively filter out noise interference. You can also select the point with the largest modulus value among the N points as the judgment point.

[0088] 13. Select the time-domain amplitude corresponding to that point as the criterion for determining whether the DMF drive system is connected. Assuming the peak value of the original signal is A, the modulus of each point in the FFT result (except the DC component of the first point) is N / 2 times A. Since the first point is the DC component, its modulus is N times the DC component. Therefore, the time-domain amplitude corresponding to that point can also be used as the judgment criterion.

[0089] 14. As shown in 13, the RMS voltage value of the original signal can also be used as the judgment condition. Sample the original signal at N points and then analyze it using FFT to obtain the RMS values ​​of the DC component, fundamental wave, and each harmonic. Then, take the square root of the sum of the squares to obtain the RMS value of the original signal.

[0090] 15. The present invention can also use the phase difference between the input signal and the voltage-dividing signal as a criterion for determining whether to connect to the DMF drive system. Two ADCs on the single-chip microcomputer simultaneously collect the input and output signals, perform FFTs on each, and then select the point with the same main frequency as the input signal as the judgment point. Phase = atan (imaginary part / real part), and phase difference = phase input - phase output are used.

[0091] 16. The detection system of the present invention includes a branch circuit, a voltage follower, a non-inverting adder, and a voltage divider circuit. Low-pass filters can be added to the back ends of the voltage follower and the non-inverting adder to filter out noise with a frequency higher than the excitation signal. This makes the voltage collected by the ADC on the microcontroller more stable and accurate.

[0092] 17. The low-pass filter in point 16 above can also be replaced by a lock-in amplifier, effectively filtering out all other frequency components.

[0093] 18. Attachment Figure 4 The HV507 in the embodiment may also be a channel selector with other numbers (eg, 16, 32 channels, etc.).

[0094] The beneficial effects of the present invention are at least:

[0095] 1. The circuit structure is greatly simplified and optimized compared to the existing system, requiring only 7 resistors and a dual operational amplifier, reducing costs;

[0096] 2. Using square waves as detection excitation signals is easy to implement and integrate into existing DMF drive systems;

[0097] 3. The algorithm is simple and improves efficiency;

[0098] Accurately detect whether 180 electrodes are connected to the DMF drive system within 4.300ms.

[0099] The feasibility has been verified by experiments. After testing, it can accurately detect whether 180 electrodes are connected to the DMF drive system within 300 milliseconds.

[0100] The present invention provides a detection method, system, and circuit capable of quickly determining whether multiple electrodes are connected to a DMF drive system on an electrowetting digital microfluidics platform. This method provides a novel solution for rapidly determining the electrical connection between a microfluidic device and a DMF drive system on an electrowetting-based digital microfluidics (DMF) platform. The detection circuit, based on impedance analysis and fast Fourier transform, uses only seven resistors and a dual operational amplifier to accurately detect the connection of at least 180 electrodes to the DMF drive system within 300 milliseconds.

[0101] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0102] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0103] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only exemplary. For example, the division of units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0104] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected to achieve the purpose of the present embodiment according to actual needs.

[0105] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0106] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program codes.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A detection method for connecting a digital microfluidic device to a DMF drive system, characterized in that: The following steps are involved: generating an excitation signal, and inputting the excitation signal into a digital microfluidic device to generate a voltage value; Performing voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device; The multiple voltage values ​​are collected multiple times and fast Fourier transform is performed to obtain the modulus values ​​of multiple points with the same frequency as the excitation signal; A preset threshold is set according to the type, voltage and frequency of the excitation signal, and the modulus values ​​of multiple points with the same frequency as the excitation signal are compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system; The preset threshold value = (connection module value min + No connection modulus max ) / 2; the connected modulus min refers to the minimum value among the multiple modulus values ​​collected when multiple electrodes are connected to the DMF drive system; the unconnected modulus max It refers to the maximum value among multiple mode values ​​collected when multiple electrodes are not connected to the DMF drive system.

2. The detection method of connecting the digital microfluidic device to the DMF drive system according to claim 1, characterized in that: The preset thresholds include: the modulus at the point equal to the main frequency, the maximum modulus after fast Fourier transform, the time domain amplitude corresponding to the point equal to the main frequency, the effective voltage value of the original signal, and the phase difference between the input signal and the divided voltage signal.

3. The detection method for connecting the digital microfluidic device to the DMF drive system according to claim 1, characterized in that: The detection method further includes selecting an excitation signal, and the selection of the excitation signal includes: The detection method is used to calculate the module value difference between electrical connection and no electrical connection at different voltages and frequencies, and the signal at the voltage and frequency when the module value difference is the largest is selected as the excitation signal.

4. The detection method for connecting a digital microfluidic device to a DMF drive system according to claim 1, wherein: After obtaining a plurality of voltage values ​​after voltage division by a plurality of electrodes in the digital microfluidic device, the detection method further comprises: performing operational amplification on the plurality of voltage values ​​to provide a load capacity thereof.

5. The detection method for connecting a digital microfluidic device to a DMF drive system according to claim 1, wherein: After obtaining multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device, the detection method further includes: performing in-phase addition operation on the multiple voltage values, and performing voltage division processing again on the voltage values ​​after the in-phase addition operation.

6. A detection system comprising a digital microfluidic device and a DMF drive system, characterized in that: include: Single chip microcomputer, channel selector, front-end voltage divider circuit; The single chip microcomputer controls the channel selector to generate an excitation signal, and the excitation signal is input into the digital microfluidic device to generate a voltage value; The front-end voltage divider circuit performs voltage division to obtain multiple voltage values ​​after voltage division of multiple electrodes in the digital microfluidic device; The single chip microcomputer collects multiple voltage values ​​for multiple times, and performs fast Fourier transform to obtain multiple modulus values ​​at points with the same frequency as the excitation signal; A preset threshold is set according to the type, voltage, and frequency of the excitation signal, and the modulus values ​​of multiple points with the same frequency as the excitation signal are compared with the preset threshold to determine whether each electrode in the digital microfluidic device is connected to the DMF drive system; The preset threshold value = (connection module value min + No connection modulus max ) / 2; the connected modulus min refers to the minimum value among the multiple modulus values ​​collected when multiple electrodes are connected to the DMF drive system; the unconnected modulus max It refers to the maximum value among multiple mode values ​​collected when multiple electrodes are not connected to the DMF drive system.

7. The detection system of the digital microfluidic device connected to the DMF drive system according to claim 6, characterized in that: The single chip computer calculates the module value difference between electrical connection and no electrical connection at different voltages and frequencies, and selects the signal at the voltage and frequency when the module value difference is the largest as the excitation signal.

8. The detection system of the digital microfluidic device connected to the DMF drive system according to claim 6, characterized in that: The detection system also includes: A voltage follower connected to the front-end voltage divider circuit, performing operational amplification on multiple voltage values ​​to increase its load capacity; an in-phase adder connected to the voltage follower and performing an in-phase addition operation on the multiple voltage values ​​after the operational amplification; The back-end voltage divider circuit is connected to the in-phase adder and performs a voltage division process again on the voltage value after the in-phase addition operation.

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