Electrochemical detection device based on rotary embedded centrifugal micro-fluidic chip and working method

Abstract

The invention discloses an electrochemical detection device based on a rotary embedded centrifugal micro-fluidic chip and a working method. The electrochemical detection device comprises an electrochemical detection chip, an electrode adaptation module, an electrochemical detection module, a driving module and a regulation and control module, a detection cavity is arranged in the chip substrate, an inner electrode of the detection electrode coincides with the bottom of the detection cavity, and an outer electrode is exposed; a contact electrode of the electrode adaptation module is in contact with the outer electrode, and a self-locking indexing pin is mounted at the bottom; the electrochemical detection module realizes signal conduction between the electrode adaptation module and a detection circuit through an electric slip ring; a motor in the driving module drives the assembly to rotate through a transmission shaft; and the regulation and control module comprises a controller, a communication interface and a display. The electrochemical detection device provided by the invention adopts a highly integrated design, has a stable contact mechanism, can realize rapid and accurate installation and dynamic rotation detection, and has the functions of high-precision signal transmission and processing and efficient driving and control.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical detection, and particularly to an electrochemical detection device and working method based on a rotary-embedded centrifugal microfluidic chip. Background Art

[0002] With the rapid development of microfluidic technology, centrifugal microfluidic chip electrochemical detection devices have shown broad application prospects in the fields of biomedical point-of-care diagnosis, rapid screening of environmental pollutants, and high-throughput analysis of food safety due to their advantages of high efficiency, low power consumption, and high integration. Centrifugal microfluidic technology can achieve full-process automation of nanoliter-scale samples through a precisely designed centrifugal chip structure, combined with the high-sensitivity characteristics of electrochemical detection methods, including sample dispensing, reagent mixing, separation and enrichment, reaction, and detection, significantly improving the detection efficiency and data reliability. However, the existing designs still face the following problems: (1) Insufficient dynamic detection ability: For example, CN105964314B relies on static alignment of electrodes after centrifugation stops, requires precise mechanical control, and has limited analysis ability for time-dependent biomarkers.

[0003] (2) Defects in long-term stability: For example, CN212748794U simplifies the installation through a mechanical spring, but has many components that are prone to aging, resulting in position deviation after long-term use.

[0004] (3) Complex system and high cost: For example, the integrated system of CN111982985A supports multi-data fusion, but relies on a high-power central processor and a multi-module collaborative architecture.

[0005] In addition, centrifugal microfluidic electrochemical detection technology is generally limited to the step-by-step mode of "centrifugal drive-static detection", unable to capture the dynamic changes of reactions in real time during rotation, and difficult to meet the requirements of point-of-care testing and high-throughput screening for efficiency and data comprehensiveness. Summary of the Invention

[0006] Aiming at the problems of insufficient dynamic detection ability, defects in long-term stability, and complexity of the existing centrifugal microfluidic detection electrochemical detection device, the present invention provides an electrochemical detection device and working method based on a rotary-embedded centrifugal microfluidic chip, which can achieve rapid and accurate positioning and dynamic rotation detection.

[0007] Specifically, the technical solutions adopted by the present invention are as follows: An electrochemical detection device based on a rotary-embedded centrifugal microfluidic chip, comprising an electrochemical detection chip, an electrode adaptation module, an electrochemical detection module, and a driving module; The electrochemical detection chip includes a chip substrate and a detection electrode located below the chip substrate. At least one detection cavity is provided in the chip substrate. At least one set of interconnected inner electrodes and outer electrodes is provided in the detection electrode. The detection area of the inner electrode coincides with the bottom surface of the detection cavity. The outer electrode is exposed outside the chip substrate. The upper surface of the detection electrode is tightly bonded to the bottom surface of the chip substrate; The electrode adapter module includes a fixing shell. The fixing shell includes a fixing outer shell with an open top. At least one card slot is connected to the inner surface of the side wall of the fixing outer shell. The left side or the right side of the card slot is open. A contact electrode is embedded in the inner wall of the top surface of the card slot. A positioning hole is provided on the bottom surface of the card slot. The positioning hole is located directly below the contact electrode. A self-locking indexing pin for improving the fitting tightness between the outer electrode and the contact electrode is installed in the positioning hole. The electrochemical detection chip is placed in the cavity of the fixing shell. When the electrochemical detection chip is not locked with the fixing shell, the electrochemical detection chip can be rotated to adjust the angle. When the outer electrode of the electrochemical detection chip is screwed into the card slot and the detection chip is locked with the fixing shell, the outer electrode is in close contact with the contact electrode; The electrochemical detection module includes an electric slip ring and an electrochemical detection circuit; The electric slip ring is located below the fixing shell and is electrically connected to the fixing shell; The driving module includes a motor. The motor drives the chip substrate, the detection electrode, the fixing shell and the electric slip ring to rotate through a transmission shaft.

[0008] Among them, a central through hole is provided in the center of both the chip substrate and the detection electrode. A through hole is provided in the center of the bottom surface of the fixing shell. A spring is provided in the through hole on the bottom surface of the fixing shell. The bottom of the spring is in contact with the fixing shell, and the top of the spring is in contact with the bottom surface of the electrochemical detection chip. The transmission shaft passes through the spring.

[0009] Among them, the electrochemical detection circuit integrates a potentiostat, a signal generation circuit, a signal acquisition circuit and a signal processing circuit; The signal acquisition circuit is electrically connected to the electric slip ring.

[0010] Among them, a regulation module is further included. The regulation module includes a controller, a communication interface and an interaction interface. The interaction interface is displayed through a display; The controller includes a motor driver and a microprocessor.

[0011] Among them, the chip substrate is made of materials such as polymethyl methacrylate, polydimethylsiloxane or glass, and the bottom surface has a microstructural design. After bonding with the detection electrode, structures such as chambers, microchannels, and valves are formed. The structure shape is determined by the sample to be measured and the functional requirements.

[0012] Among them, the number of the detection cavities is the same as the number of the inner electrodes, the outer electrodes, the contact electrodes and the self-locking indexing pins to ensure mutual cooperation.

[0013] Among them, the detection electrode is a two-electrode, three-electrode or four-electrode system, and the electrode material is metal, carbon material or semiconductor material, etc. The electrode manufacturing method adopts screen printing, vacuum evaporation, ion sputtering or molecular beam epitaxy, etc. The detection electrode is adapted to the shape of the contact electrode and can stably transmit electrical signals under the condition of close contact.

[0014] Among them, the detection cavity of the chip substrate cooperates with the inner electrode of the detection electrode. The bottom surface of the chip substrate is tightly bonded to the electrode surface of the detection electrode, and the detection cavity completely covers the inner electrode area of the detection electrode.

[0015] Among them, the outer electrode, the contact electrode and the self-locking indexing pin of the detection electrode are located on the same vertical axis, and the three are closely fitted in the locked state.

[0016] Among them, the contact electrode cooperates with the outer electrode of the detection electrode. When the electrochemical detection chip is put in, the spring is pressed hard and the outer electrode is rotated into the card slot where the contact electrode is located. After stopping pressing the spring, the electrochemical detection chip moves up under the action of the spring pressure, so that the contact electrode is adapted and fitted with the outer electrode.

[0017] Among them, the top height of the self-locking indexing pin can be manually adjusted. In the unlocked state, the top of the self-locking indexing pin does not fit with the bottom of the outer electrode. When the bottom of the self-locking indexing pin is manually rotated clockwise by 90° to make it in the locked state, the top of the self-locking indexing pin applies an upward force to the bottom of the outer electrode, so that the top of the outer electrode is closely fitted with the contact electrode. Therefore, in the high-speed rotation state, the electrochemical detection chip and the electrochemical detection module can achieve stable electrical signal transmission through the electrode adaptation module.

[0018] Among them, the electric slip ring includes a rotor and a stator. The circuit of the rotor part is connected to the electrode adaptation module, and the circuit of the stator part is connected to the electrochemical detection circuit, thereby realizing stable electrical signal connection between the rotating part and the stationary part.

[0019] Among them, the transmission shaft and the electric slip ring are fixed by bolts, and the connection is realized through the lateral pressing force, which is convenient for quick installation, replacement and regular maintenance. The cooperation method between the transmission shaft and the fixed shell and the electrochemical detection chip can be arbitrary, and can be interference fit, key connection, expansion sleeve connection, etc.

[0020] Among them, the rated speed of the motor is 4000r / min, the rated torque is 0.48 Nm, and the relative error of the rotational speed detected by the Hall sensor is ≤1%.

[0021] Among them, the electrochemical detection circuit integrates a potentiostat, a signal generation circuit, a signal acquisition circuit and a signal processing circuit, and supports various electrochemical detection modes such as cyclic voltammetry, differential pulse voltammetry and square wave voltammetry.

[0022] Among them, the potentiostat can adjust the potential range of ±5V, with an accuracy of ±1mV, the measured current range of ±1nA to ±100mA, and the scanning speed range of 0.1mV / s to 1V / s.

[0023] Among them, the signal generation circuit can output various excitation signals such as square waves, sine waves, and staircase waves, with a frequency range of 0.1Hz to 100kHz and a voltage amplitude of ±5V.

[0024] Among them, the sampling rate of the signal acquisition circuit is not less than 100kHz, and it supports 24-bit analog-to-digital conversion.

[0025] Among them, the signal processing circuit includes a low-pass filter and a programmable gain amplifier, which can capture current signals of 1nA - 100mA and meet the requirements of rapid detection.

[0026] Among them, the control module, as the core control hub of the entire device, regulates the operation of the motor and the electrochemical detection circuit through a communication interface and a controller, and displays parameters and receives instructions through an interactive interface to flexibly set the detection mode and detection parameters.

[0027] Among them, the communication interface is divided into a motor communication interface and an electrochemical detection circuit communication interface. The motor communication interface adopts the RS485 differential bus protocol, with a baud rate configured as 9600. Through a twisted pair shielded cable and impedance matching terminal design, it ensures stable anti-electromagnetic interference ability when the motor rotates at high speed. The electrochemical detection circuit communication interface adopts the USB3.0 SuperSpeed protocol, with an actual transmission rate ≥400Mbps, and supports the plug-and-play function and batch transfer mode.

[0028] Among them, the controller can adjust the motor speed and running time, where the speed adjustment range is ±4000rpm, the adjustment accuracy is ±1rpm, and it can set relevant parameters such as the detection method, detection time, and scanning rate of the electrochemical detection circuit.

[0029] Among them, the interactive interface of the display screen supports multi-touch operation, and can perform parameter setting and real-time display and saving of the motor operation status and electrochemical detection results, which is convenient for users to use.

[0030] Among them, the entire device is provided with a device housing.

[0031] The working method of the electrochemical detection device based on the rotary-embedded centrifugal microfluidic chip of the present invention is specifically as follows: aligning the central through hole of the electrochemical detection chip with the axis of the transmission shaft to ensure that the chip is placed horizontally, pressing the electrochemical detection chip downward, compressing the spring to the maximum stroke, keeping the pressing state, rotating the electrochemical detection chip so that the outer electrode is embedded in the card slot where the contact electrode is located; slowly releasing, the spring rebounds to push the electrochemical detection chip upward, and the outer electrode and the contact electrode are initially fitted; manually rotating the self-locking indexing pin, and the top of the self-locking indexing pin applies vertical upward pressure to the outer electrode to ensure a tight fit; opening the interactive interface, setting the operating process, and performing electrochemical detection. After the detection is completed, the self-locking indexing pin is rotated again to release the locking state, and the electrochemical detection chip is pressed and rotated to remove the electrochemical detection chip.

[0032] Compared with the prior art, the outstanding effects of the present invention are: (1) The electrochemical detection device based on the rotary embedded centrifugal microfluidic chip of the present invention uses the coordinated design of the fixed shell and the electric slip ring to realize the synchronous coupling of centrifugal force drive and electrochemical detection, breaking through the traditional "centrifugal drive-static detection" step-by-step detection mode; the axial displacement self-compensation mechanism constructed by the spring and the self-locking indexing pin suppresses the radial runout of the electrochemical detection chip, improves the positioning accuracy, and ensures the stable transmission of the signal during the detection process; the detection module, the control module and the interactive interface are highly integrated, the structure is simplified, the cost is reduced, and the operating status and detection results are displayed in real time, which is convenient for operation and adjustment.

[0033] (2) The device of the present invention realizes real-time electrochemical detection during the centrifugation process through synchronous signal transmission of rotary drive and electric slip ring; the screw-in installation is combined with the elastic adaptation of the electrode. During installation, it only needs to press the rotating chip and manually lock the self-locking indexing pin, which is easy to operate and reduces damage to the electrode; the embedded layout improves the system integration and portability, supports the automation of the entire process of "sampling-detection-analysis", and is suitable for a variety of immediate application scenarios such as precision medicine, environmental monitoring and food safety.

[0034] The electrochemical detection device and working method based on the spin-embedded centrifugal microfluidic chip of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an exploded diagram of the internal structure of the electrochemical detection device based on the spin-embedded centrifugal microfluidic chip.

[0036] Figure 2 Schematic diagram of the connection of the electrochemical detection device based on the spin-embedded centrifugal microfluidic chip.

[0037] Figure 3 This is a cross-sectional view of the internal structure of an electrochemical detection device based on a spin-embedded centrifugal microfluidic chip.

[0038] Figure 4 It is a schematic diagram of an electrochemical detection chip.

[0039] Figure 5 It is a schematic diagram of a fixing shell.

[0040] Figure 6 It is an overall schematic diagram of an electrochemical detection device based on a rotary-embedded centrifugal microfluidic chip.

[0041] Figure 7 It is the experimental result of potassium ferricyanide concentration dilution.

[0042] Among them, 1 - chip substrate, 101 - detection cavity; 2 - detection electrode, 201 - inner electrode, 202 - outer electrode; 3 - fixing shell, 301 - positioning hole, 302 - contact electrode, 303 - fixing outer shell, 304 - card slot; 4 - self-locking indexing pin; 5 - spring; 6 - transmission shaft; 7 - electrical slip ring; 8 - motor; 9 - electrochemical detection circuit; 10 - regulation module; 11 - device outer shell; 12 - display. Specific implementation mode

[0043] As Figures 1-6 shown, an electrochemical detection device based on a rotary-embedded centrifugal microfluidic chip includes an electrochemical detection chip, an electrode adaptation module, an electrochemical detection module, and a driving module.

[0044] The electrochemical detection chip includes a chip substrate 1 and a detection electrode 2 located below the chip substrate 1. There are 4 detection cavities 101 evenly distributed along the circumferential direction in the chip substrate 1. There are 4 groups of interconnected inner electrodes 201 and outer electrodes 202 evenly distributed in the detection electrode 2. The detection areas of the 4 inner electrodes 201 coincide with the bottom surfaces of the 4 detection cavities 101. The outer electrodes 202 are exposed outside the chip substrate 1. The upper surface of the detection electrode 2 is tightly bonded to the bottom surface of the chip substrate 1.

[0045] The electrode adaptation module includes a fixed housing 3, and the fixed housing 3 includes a fixed outer shell 303 with an open top. Four card slots 304 are connected to the inner surface of the side wall of the fixed outer shell 303. The left or right side of the card slot 304 is open. A contact electrode 302 is embedded in the inner wall of the top surface of the card slot 304. A positioning hole 301 is provided on the bottom surface of the card slot 304, and the positioning hole 301 is located directly below the contact electrode 302. A self-locking indexing pin 4 for fixing the contact electrode 302 is installed in the positioning hole 301. When the electrochemical detection chip is not locked with the fixed housing 3, the electrochemical detection chip can be rotated to adjust the angle. When the outer electrode 202 of the electrochemical detection chip is screwed into the card slot 304 and the electrochemical detection chip is locked with the fixed housing 3, the outer electrode 202 is in close contact with the contact electrode 302. The top edge of the fixed housing 3 can be treated with a chamfer for smoothness to avoid sharp right angles or edges, so as to reduce damage caused by collision or scratching during use.

[0046] The electrochemical detection module includes a slip ring 7 and an electrochemical detection circuit 9; the slip ring 7 is located below the fixed housing 3 and is electrically connected to the fixed housing 3.

[0047] The drive module includes a motor 8, and the motor 8 drives the chip substrate 1, the detection electrode 2, the fixed housing 3, and the slip ring 7 to rotate through a transmission shaft 6.

[0048] Central through holes are provided in both the chip substrate 1 and the detection electrode 2. A through hole is provided in the center of the bottom surface of the fixed housing 3. A spring 5 is provided in the through hole on the bottom surface of the fixed housing 3. The bottom of the spring 5 is in contact with the fixed housing 3, and the top of the spring 5 is in contact with the bottom surface of the electrochemical detection chip. The transmission shaft 6 passes through the spring 5.

[0049] The electrochemical detection circuit 9 integrates a potentiostat, a signal generation circuit, a signal acquisition circuit, and a signal processing circuit; the signal acquisition circuit is electrically connected to the slip ring 7.

[0050] It further includes a regulation module 10, and the regulation module 10 includes a controller, a communication interface, and a display 12; the controller includes a motor driver and a microprocessor.

[0051] The chip substrate 1 is made of materials such as polymethyl methacrylate, polydimethylsiloxane, or glass, and has a microstructure design on the bottom surface.

[0052] The detection electrode 2 is adapted to the shape of the contact electrode 302 and can stably transmit electrical signals under close contact conditions. The detection electrode 2 is a two-electrode, three-electrode, or four-electrode system, and the electrode material is a metal, a carbon material, or a semiconductor material, etc. The electrode manufacturing method adopts screen printing, vacuum evaporation, ion sputtering, or molecular beam epitaxy, etc.

[0053] The electrochemical detection chip is formed by bonding a chip substrate 1 with a microstructural design and a detection electrode 2. During the bonding process, the detection cavity 101 is aligned and overlapped with the inner electrode 201 of the detection electrode. After bonding, the bottom surface of the chip substrate 1 is tightly bonded to the electrode surface of the detection electrode 2, forming structures such as chambers, microchannels, and valves.

[0054] The number of detection cavities 101 in the electrochemical detection chip is the same as the number of inner electrodes 201, outer electrodes 202, contact electrodes 302, and self-locking indexing pins 4. The contact electrode 302 cooperates with the outer electrode 202 of the detection electrode. When the electrochemical detection chip is inserted, the spring 5 is pressed firmly and the outer electrode 202 is rotated into the card slot 304 where the contact electrode 302 is located. After stopping pressing the spring 5, the electrochemical detection chip moves upward under the pressure of the spring 5, enabling the contact electrode 302 to fit and bond with the outer electrode 202.

[0055] The top height of the self-locking indexing pin 4 can be manually adjusted. In the unlocked state, the top of the self-locking indexing pin does not fit with the bottom of the outer electrode 202. By manually rotating the self-locking indexing pin to the locked state, the top of the self-locking indexing pin applies an upward force to the bottom of the outer electrode 202, causing the top of the outer electrode 202 to fit tightly with the contact electrode 302. Therefore, even in a high-speed rotation state, the electrochemical detection chip and the electrochemical detection module can still achieve stable electrical signal transmission through the electrode adaptation module.

[0056] The electric slip ring 7 includes a rotor and a stator. The circuit of the rotor part is connected to the electrode adaptation module, and the circuit of the stator part is connected to the electrochemical detection circuit. The drive shaft and the electric slip ring are fixed by bolts, and the connection is achieved through a lateral pressing force, facilitating quick installation, replacement, and regular maintenance. The cooperation mode between the drive shaft and the fixed housing and the electrochemical detection chip can be arbitrary, such as interference fit, key connection, shrink fit connection, etc.

[0057] The rated speed of the motor is 4000 rpm, and the rated torque is 0.48 Nm. The relative error of the rotational speed detected by the Hall sensor is ≤1%.

[0058] The electrochemical detection circuit integrates a potentiostat, a signal generation circuit, a signal acquisition circuit, and a signal processing circuit, and can implement various electrochemical detection modes such as cyclic voltammetry, differential pulse voltammetry, and square wave voltammetry. The potentiostat can adjust the potential range of ±5V, with an accuracy of ±1mV, the measured current range of ±1nA to ±100mA, and the scanning speed range of 0.1mV / s to 1V / s. The signal generation circuit can output various excitation signals such as square waves, sine waves, and staircase waves, with a frequency range of 0.1Hz to 100kHz and a voltage amplitude of ±5V. The sampling rate of the signal acquisition circuit is not less than 100kHz, and it supports 24-bit analog-to-digital conversion. The signal processing circuit includes a low-pass filter and a programmable gain amplifier, which can capture current signals of 1nA - 100mA to meet the requirements of rapid detection.

[0059] As the core control hub of the entire device, the control module regulates the operation of the motor and the electrochemical detection circuit through the communication interface and the controller, and displays parameters and receives instructions through the interaction interface to flexibly set the detection mode and detection parameters.

[0060] The communication interface is divided into a motor communication interface and an electrochemical detection circuit communication interface. The motor communication interface uses the RS485 differential bus protocol, with a baud rate configured as 9600, and is designed with a twisted shielded cable and an impedance matching terminal to ensure stable anti-electromagnetic interference ability during high-speed rotation of the motor; the electrochemical detection circuit communication interface uses the USB3.0 SuperSpeed protocol, with an actual transmission rate ≥400Mbps, and supports the plug-and-play function and the bulk transfer mode.

[0061] The controller can adjust the motor speed and running time, where the speed adjustment range is ±4000rpm, the adjustment accuracy is ±1rpm, and it can set relevant parameters such as the detection method, detection time, and scanning rate of the electrochemical detection circuit.

[0062] The interaction interface of the display screen 12 supports multi-touch operations, and can perform parameter setting, real-time display, and saving of the motor operation status and electrochemical detection results, which is convenient for users to use.

[0063] The entire device is provided with a device housing 11.

[0064] The working method of the electrochemical detection device is as follows: Align the central through-hole of the electrochemical detection chip with the axis of the drive shaft to ensure that the chip is placed horizontally. Press down the electrochemical detection chip to compress the spring to its maximum stroke, and keep the pressing state. Rotate the electrochemical detection chip to embed the outer electrode into the card slot where the contact electrode is located. Slowly release the pressure, and the spring rebounds to push the electrochemical detection chip upward, and the outer electrode is initially fitted with the contact electrode. Manually rotate the self-locking indexing pin, and the top of the self-locking indexing pin applies a vertically upward pressure to the outer electrode to ensure tight fitting. Open the interactive interface, set the operation process, and perform electrochemical detection. After the detection is completed, rotate the self-locking indexing pin counterclockwise to release the locking state, press, rotate, and remove the electrochemical detection chip.

[0065] Its working principle is as follows: The sample is injected into the electrochemical detection chip through the sample injection port. The motor in the drive module drives the electrochemical detection chip, the electrode adapter module, and the electrical slip ring to rotate through the drive shaft. Under the action of centrifugal force, it flows along the micro-structure and enters the detection chamber to complete the reagent mixing and reaction. At the same time, the electrochemical detection module real-time collects the electrical signals on the inner electrode through the electrode adapter module and the electrical slip ring. The signals are processed by the potentiostat, the signal generation circuit, and the signal acquisition circuit, and then transmitted to the control module for data analysis and result display. Application example (Potassium ferricyanide concentration dilution experiment)

[0066] The purpose of this experiment is to use the centrifugal microfluidic chip to achieve the concentration dilution of 100 mM potassium ferricyanide solution, and use this device to achieve the differential pulse voltammetry determination of potassium ferricyanide solutions with different concentrations after dilution.

[0067] 1. Preparation of electrochemical detection chip (1) Fabrication of chip substrate: Use Solidworks 3D software to design the chip structure mold and save it as an STL format file. Import the file into a high-precision stereolithography 3D printer, put in the SLA resin, and print the mold layer by layer. After printing, put the mold into a 75% alcohol solution, ultrasonically clean it for 10 min, dry it, put it into an ultraviolet curing box and irradiate it for 10 min, and place it in an oven at 60 °C for 12 hours to ensure its complete curing. Then wind the edge with transparent tape for one week. Mix the PDMS prepolymer and the curing agent in a ratio of 10:1 and stir evenly. Slowly pour the mixture into the mold, ensure that the micro-structure on the mold surface is completely filled, and then degas it under vacuum for 30 minutes to remove tiny bubbles. Place the mold and the mixture in an oven at 60 °C and dry for 12 hours to completely cure the PDMS. After cooling, carefully peel off the PDMS chip substrate and check the integrity of the micro-channels.

[0068] (2) Fabrication of detection electrodes: Electrodes were fabricated on a polymethyl methacrylate substrate using screen printing technology. First, conductive silver paste was printed on the polymethyl methacrylate substrate to form electrode strips, which were cured in an oven at 70 °C for 30 min. Second, conductive carbon paste was printed to form the working electrode and the auxiliary counter electrode, which were cured in an oven at 70 °C for 20 min. Finally, a silver / silver chloride reference electrode was printed and cured at room temperature for 12 hours.

[0069] (3) Bonding of the chip substrate and the detection electrodes: After cleaning the surfaces of the chip substrate and the detection electrodes with absolute ethanol, a UV curable adhesive was applied to the chip substrate with a thickness of 5 - 10 μm, taking care to avoid the microstructures to prevent blockage. The detection electrodes were precisely aligned and attached to the chip substrate at the preset position and angle, and then irradiated with a UV lamp for 15 min to completely cure the adhesive layer, ensuring a stable bonding strength between the chip substrate and the detection electrodes.

[0070] 2. Instrument preparation and detection (1) Detection preparation: The electrochemical detection chip was placed into the detection device, and its central through-hole was aligned with the axis of the drive shaft to ensure that the chip was placed horizontally. Press down on the electrochemical detection chip to compress the spring to its maximum stroke and maintain the pressing state. Rotate the electrochemical detection chip to embed the outer electrode into the groove where the contact electrode is located. Slowly release the pressing force, and the spring rebounds to push the electrochemical detection chip upward, causing the outer electrode to be initially in contact with the contact electrode. Rotate the bottom of the self-locking indexing pin clockwise by 90°, causing its top to pop out and apply a vertically upward pressure to the outer electrode to ensure a tight fit between the outer electrode and the contact electrode. After installation, 0.5 ml of 100 mmol / L potassium ferricyanide solution was added from the sample loading port using a pipette, and 1 ml of 0.1 mol / L potassium chloride solution was added from the diluent loading port.

[0071] (2) Detection process: Open the interactive interface. After checking normal communication, set the operation process and detection parameters. The operation process is to run at 1000 rpm for 3 min, then at 2500 rpm for 3 min to allow the potassium ferricyanide solution and the potassium chloride solution to enter the quantitative chamber for quantification respectively, and then run at 3500 rpm for 5 minutes to allow the potassium ferricyanide solution and the potassium chloride solution in the quantitative chamber to enter the detection chamber and mix thoroughly. The detection parameters are set as differential pulse voltammetry, with an initial potential of -0.2 V, a termination potential of 0.4 V, a potential increment of 0.004 V, a pulse amplitude of 0.05 V, a pulse width of 0.05 s, a sampling width of 0.016 s, a pulse period of 0.5 s, a rest time of 2 s, and a sensitivity of 1e-4 / V. Click Start to run, and the interface will display the real-time running speed curve of the motor and the detection result curve. After the run is completed, save the results (such as Figure 7 ), rotate the self-locking indexing pin counterclockwise by 90° to release the locking state, press, rotate, and remove the electrochemical detection chip.

[0072] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An electrochemical detection device based on a spin-embedded centrifugal microfluidic chip, characterized in that: It includes an electrochemical detection chip, an electrode adapter module, an electrochemical detection module and a driving module; The electrochemical detection chip comprises a chip substrate (1) and a detection electrode (2) located below the chip substrate (1); the chip substrate (1) is provided with at least one detection cavity (101); the detection electrode (2) is provided with at least one group of inner electrodes (201) and outer electrodes (202) connected to each other; the detection area of ​​the inner electrode (201) coincides with the bottom surface of the detection cavity (101); the outer electrode (202) is exposed outside the chip substrate (1); and the upper surface of the detection electrode (2) is tightly bonded to the bottom surface of the chip substrate (1); The electrode adaptation module comprises a fixed shell (3), the fixed shell (3) comprising a fixed shell (303) with a top opening, at least one slot (304) connected to the inner surface of the side wall of the fixed shell (303), the left side or right side of the slot (304) being open, a contact electrode (302) being embedded on the inner wall of the top surface of the slot (304), a positioning hole (301) being provided on the bottom surface of the slot (304), the positioning hole (301) being located directly below the contact electrode (302), The positioning hole (301) contains a self-locking indexing pin (4) for improving the tightness of the fit between the outer electrode (202) and the contact electrode (302); the electrochemical detection chip is placed in the cavity of the fixed shell (3); when the electrochemical detection chip and the fixed shell (3) are not locked, the electrochemical detection chip can be rotated to adjust the angle; when the outer electrode (202) of the electrochemical detection chip is screwed into the slot (304) and the electrochemical detection chip and the fixed shell (3) are locked, the outer electrode (202) and the contact electrode (302) are tightly fitted.

2. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The chip substrate (1) and the detection electrode (2) are both provided with a central through hole in the center, the bottom surface of the fixed shell (3) is provided with a through hole in the center, a spring (5) is provided in the through hole on the bottom surface of the fixed shell (3), the bottom of the spring (5) is in contact with the fixed shell (3), the top of the spring (5) is in contact with the bottom surface of the electrochemical detection chip, and the transmission shaft (6) passes through the spring (5).

3. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The electrochemical detection circuit (9) integrates a constant potential instrument, a signal generation circuit, a signal acquisition circuit and a signal processing circuit; the signal acquisition circuit is electrically connected to the electric slip ring (7).

4. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The electrochemical detection module comprises an electric slip ring (7) and an electrochemical detection circuit (9); the electric slip ring (7) is located below the fixed shell (3) and is electrically connected to the fixed shell (3); The driving module comprises a motor (8), and the motor (8) drives the chip substrate (1), the detection electrode (2), the fixed shell (3) and the electric slip ring (7) to rotate via a transmission shaft (6).

5. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: It also comprises a control module (10), the control module (10) comprising a controller, a communication interface and a display (12); the controller comprises a motor driver and a microprocessor.

6. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The electrochemical detection chip is formed by bonding a chip substrate (1) with a microstructure design and a detection electrode (2), and after bonding, a chamber, a microchannel, and a valve structure are formed; the number of detection chambers (101) of the electrochemical detection chip is the same as the number of inner electrodes (201), outer electrodes (202), contact electrodes (302), and self-locking indexing pins (4).

7. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The chip substrate is made of polymethyl methacrylate, polydimethylsiloxane or glass.

8. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The detection electrode is a two-electrode, three-electrode or four-electrode system, the electrode material is a metal, a carbon material or a semiconductor material, and the electrode manufacturing method adopts screen printing, vacuum evaporation, ion sputtering or molecular beam epitaxy.

9. The electrochemical detection device based on a spin-embedded centrifugal microfluidic chip according to claim 1, characterized in that: The electric slip ring (7) comprises a rotor and a stator, the circuit of the rotor part is connected to the electrode adapter module, and the circuit of the stator part is connected to the electrochemical detection circuit.

10. The working method of the electrochemical detection device based on the spin-embedded centrifugal microfluidic chip according to any one of claims 1 to 9, characterized in that: Align the central through hole of the electrochemical detection chip with the axis of the transmission shaft to ensure that the chip is placed horizontally, press the electrochemical detection chip downward, compress the spring to the maximum stroke, keep the pressing state, and rotate the electrochemical detection chip so that the outer electrode is embedded in the card slot where the contact electrode is located; slowly release it, and the spring rebounds to push the electrochemical detection chip upward, and the outer electrode and the contact electrode are initially fitted; manually rotate the self-locking indexing pin, and the top of the self-locking indexing pin applies vertical upward pressure to the outer electrode to ensure a tight fit; Open the interactive interface, set the running process, and perform electrochemical detection. After the detection is completed, rotate the self-locking indexing pin again to release the locking state, press and rotate, and remove the electrochemical detection chip.

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