CN219978182U - Electrochemical detector - Google Patents

Abstract

The utility model discloses an electrochemical detector, which belongs to the technical field of electrochemical detection and solves the technical problems of large volume, inconvenient movement or single function of the existing detector; the main control chip module is connected with the control end of the constant potential control module; the microfluidic chip comprises an electrode plate and a bonding sheet, wherein the electrode plate is provided with a first reaction tank, a second reaction tank, a counter electrode and a reference electrode, a first working electrode is arranged in the first reaction tank, a second working electrode is arranged in the second reaction tank, the first working electrode and the second working electrode share the counter electrode and the reference electrode, the bonding sheet is provided with a first detection area and a second detection area which are mutually separated, the first detection area is provided with a first reaction substance, and the second detection area is provided with a second reaction substance; the constant potential control module is connected with the counter electrode and the reference electrode, and the main control chip module is connected with the first working electrode and the second working electrode.

Description

Electrochemical detector

Technical Field

The utility model relates to the technical field of electrochemical detection, in particular to an electrochemical detector.

Background

Electrochemical detection techniques generally refer to a technique that utilizes the electrochemical characteristics of the substance under test itself, or the redox reaction with a specific sensitive element, to generate corresponding electrochemical response signals, and the corresponding electrochemical sensors collect the response signals, convert the response signals into identifiable and detectable electrical signals, and perform analysis processing on the electrical signals. The portable electrochemical detection is taken as a detection method with high precision, high repeatability, low cost and simplicity, can feed back the electrochemical reaction in real time, can reflect the electrochemical characteristics such as the content of the detected substance and the like through the collected electric signals, and provides a new approach for miniaturization, portability and high integration level of an electrochemical detection system. The electrochemical detection method is an experimental method and detection means which are gradually developed on the basis of continuous improvement and development, and is widely applied in the fields of life science, physics, new energy, new materials, environment and the like. Among these methods, the most widely used are cyclic methods, dissolution methods, timing methods, square wave methods, differential voltammetry and electrical impedance methods.

With the development of technology, electrochemical detection technology is playing an irreplaceable role in various fields. The electrochemical detection instrument is also continuously developed towards high integration and high intellectualization. Various electrochemical detection means are widely applied to intelligent terminals such as smart phones, PCs, flat plates and the like for electrochemical detection and quantitative detection. The current commonly used biological sensing methods mainly comprise: amperometric electrochemical methods, potentiometric electrochemical methods and conductometric electrochemical methods. The classification is based on the difference in detection signal parameters of the electrochemical detection device.

Patent CN209559811U discloses a multi-parameter electrochemical detection electrode slice, including base plate, reference electrode and a plurality of working electrode, every working electrode has respective siphon runner, and the electrode slice still includes the pipette, and the pipette is connected with base plate fixed, and the pipette communicates with a plurality of siphon runners. The liquid to be measured is sucked into the liquid suction pipe and then guided to the reference electrode and each working electrode through the siphon flow channel.

The following drawbacks of the prior art:

although the detection precision of the large detector in the hospital is high, the large detector is quite expensive and inconvenient and cannot be detected at any time. The traditional test bench has the defects of large volume, inconvenient action, low test efficiency and the like, and cannot meet the requirements of field test and high-efficiency test.

All blood glucose meters and uric acid meters in the market are developed to be mature, but have single functions, and constant potential driving voltage can not be regulated automatically in detection, so that only a single target detection can be fixed.

Disclosure of Invention

The present utility model has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present utility model is to provide an electrochemical detector.

The technical scheme of the utility model is as follows: an electrochemical detector comprises a main control chip module, a constant potential control module and a micro-fluidic chip; the main control chip module is connected with the control end of the constant potential control module; the microfluidic chip comprises an electrode plate and a combining plate positioned at the top of the electrode plate, the electrode plate comprises a first carrier, a first reaction tank, a second reaction tank, a counter electrode and a reference electrode are respectively arranged at the top of the first carrier, a first working electrode is arranged in the first reaction tank, a second working electrode is arranged in the second reaction tank, the first working electrode and the second working electrode share the counter electrode and the reference electrode, the combining plate comprises a second carrier, the second carrier is provided with a first detection area corresponding to and communicated with the position of the first reaction tank and a second detection area corresponding to and communicated with the position of the second reaction tank, the first detection area and the second detection area are mutually separated, a first reaction substance is arranged in the first detection area, and a second reaction substance is arranged in the second detection area; the output end of the counter electrode of the constant potential control module is connected with the counter electrode, the output end of the reference electrode of the constant potential control module is connected with the reference electrode, and the main control chip module is connected with the first working electrode and the second working electrode.

As a further improvement, the first carrier is hydrophobic cloth, the second carrier is non-woven fabric, and the first detection area and the second detection area are separated from each other by hydrophobic ink.

Further, the first working electrode and the second working electrode are respectively provided with a round part, the counter electrode is respectively provided with a first annular part corresponding to the round parts of the first working electrode and the second working electrode, the reference electrode is respectively provided with a second annular part corresponding to the round parts of the first working electrode and the second working electrode, and the first annular part and the second annular part are positioned at two sides of the corresponding round parts.

Further, the microfluidic chip further comprises a bottom plate for mounting the electrode plate and the bonding plate.

Further, the bottom plate is a PVC sheet, and the electrode plate and the bonding plate are bonded at the top of the bottom plate.

Further, the first reactant is a glucose reactant and the second reactant is a uric acid reactant.

Further, the device also comprises a signal processing optimization module, wherein the first working electrode and the second working electrode are connected with the main control chip module through the signal processing optimization module.

Further, the display module, the storage module and the key module are respectively connected with the main control chip module.

Further, the main control chip module is an STM32 system singlechip.

Further, the display module is an LCD1602 liquid crystal display, and the storage module is a FLASH memory.

Advantageous effects

Compared with the prior art, the utility model has the advantages that:

1. the utility model can detect and display the results of targets with different concentrations independently, and can detect two targets with different concentrations on one chip at the same time and display the results on a screen in real time. On one hand, the consumption of test paper is reduced, and on the other hand, the complicated operation of respectively detecting the two targets is also reduced.

2. The constant potential control module can flexibly adjust constant potential voltage and amplification factor through the sliding rheostat according to detection requirements, and can adapt to various electrochemical detection requiring different constant voltages by adopting a chronoamperometry.

3. The carrier of the electrode plate is hydrophobic cloth, the carrier of the bonding sheet is non-woven fabric, the two materials are good in flexibility and low in cost, the problem of high cost of glass fiber, NC film and the like in the market is avoided, and the practicability and universality of the chip are further improved.

Drawings

FIG. 1 is a schematic diagram of the present utility model;

FIG. 2 is a schematic view of the structure of an electrode sheet according to the present utility model;

FIG. 3 is a schematic view of a bonding pad according to the present utility model;

FIG. 4 is a schematic diagram of a microfluidic chip according to the present utility model;

FIG. 5 is a schematic diagram of the fabrication of an electrode sheet according to the present utility model;

FIG. 6 is a schematic diagram of a main control chip module according to the present utility model;

FIG. 7 is a schematic diagram of a circuit for converting 5V to + -12V in a power module according to the present utility model;

FIG. 8 is a schematic diagram of a circuit for converting 5V to 3.3V in the power module according to the present utility model;

FIG. 9 is a reset circuit diagram of the present utility model;

FIG. 10 is a schematic diagram of a crystal oscillator clock circuit according to the present utility model;

FIG. 11 is a schematic diagram of a liquid crystal display circuit according to the present utility model;

FIG. 12 is a schematic diagram of a key module circuit according to the present utility model;

FIG. 13 is a schematic diagram of a sensor switch control circuit according to the present utility model;

FIG. 14 is a schematic diagram of a program download and serial communication circuit according to the present utility model;

FIG. 15 is a schematic diagram of a potentiostatic circuit according to the present utility model;

FIG. 16 is a schematic diagram of an IV conversion circuit according to the present utility model;

FIG. 17 is a schematic diagram of a signal amplifying and filtering circuit according to the present utility model;

FIG. 18 is a schematic diagram of a hardware zeroing circuit in accordance with the present utility model;

fig. 19 shows a FLASH memory circuit of the utility model.

Wherein: the device comprises an A-main control chip module, a B-constant potential control module, a C-micro-fluidic chip, a D-electrode plate, an E-binding plate, an F-first reaction tank, a G-second reaction tank, an H-counter electrode, an I-reference electrode, a J-first working electrode, a K-second working electrode, an L-first detection area, an M-second detection area, O-hydrophobic ink, a P-circular part, a Q-first annular part, an R-second annular part, an S-bottom plate, a T-signal processing optimization module, a U-display module, a V-storage module and a W-key module.

Detailed Description

The utility model will be further described with reference to specific embodiments in the drawings.

Referring to fig. 1 to 19, an electrochemical detector comprises a main control chip module a, a constant potential control module B and a microfluidic chip C; the main control chip module A is connected with the control end of the constant potential control module B; the microfluidic chip C comprises an electrode slice D and a combination slice E positioned at the top of the electrode slice D, the electrode slice D comprises a first carrier, the top of the first carrier is respectively provided with a first reaction tank F, a second reaction tank G, a counter electrode H and a reference electrode I, a first working electrode J is arranged in the first reaction tank F, a second working electrode K is arranged in the second reaction tank G, the first working electrode J and the second working electrode K share the counter electrode H (CE) and the reference electrode I (RE), the combination slice E comprises a second carrier, the second carrier is provided with a first detection area L which corresponds to and is communicated with the first reaction tank F in position and a second detection area M which corresponds to and is communicated with the second reaction tank G in position, the first detection area L and the second detection area M are mutually separated, the first detection area L is provided with a first reaction substance, and the second detection area M is provided with a second reaction substance; the output end of the counter electrode of the constant potential control module B is connected with the counter electrode H, the output end of the reference electrode of the constant potential control module B is connected with the reference electrode I, and the main control chip module A is connected with the first working electrode J and the second working electrode K.

The two reaction tanks are provided with respective working electrodes, and share a Reference Electrode (RE) and a Counter Electrode (CE), and the currents on the working electrodes of the two reaction tanks are not interfered with each other. The detection device can be used for detecting targets with different concentrations independently, and can also be used for simultaneously detecting targets with two different concentrations on one chip and displaying results on a screen in real time. On one hand, the consumption of test paper is reduced, and on the other hand, the complicated operation of respectively detecting the two targets is also reduced.

As shown in fig. 2, the first working electrode J and the second working electrode K are each provided with a circular portion P, the counter electrode H is provided with a first annular portion Q corresponding to the circular portion P of the first working electrode J and the second working electrode K, the reference electrode I is provided with a second annular portion R corresponding to the circular portion P of the first working electrode J and the second working electrode K, and the first annular portion Q and the second annular portion R are located at both sides of the corresponding circular portion P.

In this embodiment, the first carrier is a hydrophobic fabric, the second carrier is a non-woven fabric, and the first detection area L and the second detection area M are separated from each other by a hydrophobic ink O. The two materials have good flexibility and low cost, so that the problem of high cost of glass fiber, NC film and the like in the market is avoided, and the practicability and universality of the chip are further improved.

The microfluidic chip C also comprises a bottom plate S for mounting the electrode plate D and the bonding plate E. The bottom plate S is a PVC thin plate, and the electrode sheet D and the bonding sheet E are bonded on the top of the bottom plate S.

The electrode sheet size was 26 x 33mm, each electrode was 4.5mm wide and 6mm high, the electrode center point (two circles P) spacing was 7.5mm, and the bonding sheet size was 23 x 33mm.

As shown in fig. 5, the manufacturing process of the electrode sheet D is mainly obtained by a screen printing technology, and first, the electrode screen plate of the electrode sheet and the channel screen plate of the detection sheet are designed by Adobe Illustrator CS software, and the screen plate can be used for screen printing after being processed by the company of the open screen printing equipment. The processing process of the electrode plate is divided into two steps, firstly, the conductive carbon paste is printed on the hydrophobic cloth through the electrode screen of the electrode plate to form electrode patterns, and the hydrophobic cloth material ensures that the solution does not circulate between the two reaction tanks, so that the two reaction tanks are isolated from each other and are not interfered with each other. Then, the cloth with the electrode pattern was dried at room temperature to stably cure the electrode. The processing process of the detection sheet is similar to that of the electrode sheet, hydrophobic ink is needed to be used for preparing the detection sheet in the first step, and the preparation of the hydrophobic ink is carried out by the ink and slow-drying water according to the following ratio of 5:1, and the ink prepared in the second step is printed on non-woven fabrics through a channel screen to form two independent isolated detection areas. And finally drying and solidifying at room temperature.

After the electrode slice D and the bonding slice E are prepared, the bonding slice E is assembled and overlapped on the bottom plate S with a fixed size in sequence according to the upper sequence of the electrode slice D, and one side of the bonding slice E exceeds the electrode slice D by 2mm, so that the bonding slice E can be adhered on the adhesive bottom plate S, and the fiber-based microfluidic chip can be successfully prepared.

The first reactant is a glucose reactant and the second reactant is a uric acid reactant. The preparation process of the reaction reagent comprises the following steps: first, 8. Mu.L of 0.1% Tween solution (Tween solution) was added dropwise to each of the two detection areas, followed by drying in a 33-degree air-blast drying oven for ten minutes, which step was to greatly increase the hydrophilicity of the detection areas. Next, 5 μl of glucose oxidase solution was added dropwise to the first detection zone, 5 μl of urate oxidase solution was added dropwise to the first detection zone, and the mixture was dried in a 28 ° air-blast oven for three minutes, so that the detection sheet of the glucose and urate dual-detection sensor was completed.

The utility model also comprises a signal processing optimizing module T, wherein the first working electrode J and the second working electrode K are connected with the main control chip module A through the signal processing optimizing module T.

The utility model also comprises a display module U, a storage module V and a key module W, wherein the main control chip module A is respectively connected with the display module U, the storage module V and the key module W. The main control chip module A is an STM32 system singlechip. The display module U is an LCD1602 liquid crystal display, and the storage module V is a FLASH memory.

Fig. 6 to 19 are circuit diagrams of the present utility model.

The power supply module of the main control chip module a is shown in fig. 8, and the power supply of the main control chip module a cannot exceed 3.3V at the highest, but the external power supply is not matched to supply power for the main control chip. Therefore, the linear voltage stabilizer LD1117DT33CTR is selected as the processor, and the reference voltage slice LM336 performs matching zero setting on the 2.5V reference voltage input into the A/D converter before the processor is input into the A/D converter.

The reset module circuit is shown in fig. 9. The instrument generally also requires a reset and reset function. When the button is turned off, C39 charges, nRST is high, C32 releases current when the button is pressed, R43 keeps the current on nRST no more than 3.3V when the button is turned off, and C39 charges again after the button is restored. During hundreds of ns of key restarts, nRST will remain low, generating a system reset.

The clock crystal oscillator circuit is shown in fig. 10, and the accurate operation of the microprocessor is not separated from the clock circuit. The clock circuit is just like the heart of the microprocessor, and the clock generated by the crystal oscillator is distributed to all operations of the microprocessor, so that the clock circuit runs according to the set frequency, and the accurate operation of the whole microprocessor can be ensured. The main control chip comprises an internal clock and an external clock, which are matched with each other to provide clocks for various places needing the clocks, and which clock can be used for adjusting and designing on a software program. In the design, an 8M crystal oscillator group is used as a crystal oscillator in a clock circuit, and the 8M crystal oscillator generates oscillation to provide a clock signal for a system.

The hardware design and serial communication circuit for debugging and downloading the program is shown in fig. 14, and the design uses a Jlink downloading mode. The Jlink is convenient and quick to use, is connected with a USB port of the upper computer by a Jlink connector, and is used for debugging and simulating program codes on a computer through Keil5 to check whether the program is normal and effective. The serial communication main function is used for debugging and detecting various peripheral signals of the microprocessor, and because the serial communication program is concise, the debugging of various peripheral devices can be facilitated, and when programming, a serial assistant is needed to observe various data of the microprocessor. When the ADC is used for sampling, a serial communication assistant observes the sampled signal, and adjusts conversion time, baud rate, sampling rate and the like according to the sampled signal.

The constant potential control module B comprises two constant potential modules and a sensor control module, wherein the sensor control module selects a P-channel metal oxide semiconductor AO3401 and an NPN triode C9013 to form a control circuit, and the constant potential modules comprise two precise reference voltage source chips ADR441.

The sensor control circuit schematic diagram is shown in fig. 13, and as a detecting instrument, a function of starting and closing detection is required. If the sensor is in a working state immediately after the sensor is started, the sensor is damaged due to overlarge load, and the power consumption can also rise linearly. Therefore, a sensor control circuit needs to be designed, whether the sensor works or not is controlled by pressing a key, and the ADC only starts sampling when the sensor starts to work. When the detection is finished, the key is pressed down, and the microprocessor controls the stopping actions of the sensor and the analog-to-digital converter. The main control chip is programmed to send different signals to control the MOS tube as a switch to control the working state of the sensor. The voltage emitted by the MOS tube is controlled to have potential or not at the working electrode and the reference electrode, so that whether the reaction can occur or not is determined. The P-channel mos transistor AO3401 and NPN transistor C9013 are selected to form a control circuit as shown in fig. 18. For the P-channel MOS tube, the threshold voltage is-1.3V, and when the applied voltage is lower than the threshold voltage, the MOS tube is conducted to make the drain voltage equal to the source voltage; instead, the metal oxide semiconductor is cut off and the drain voltage is 0. For NPN type C9013, the transistor is turned on when its base voltage is greater than the emitter voltage, whereas the transistor is turned off.

The potentiostatic module circuit schematic is shown in fig. 15, with U16ADR440 providing a voltage of 2.048V input from the positive input of U17OPA124, and U17ADR441 applying this voltage to the reference electrode, which is then followed by a negative input. The C19 capacitance functions as a compensation capacitance.

The signal processing optimization module T comprises an IV conversion circuit module, a signal amplification filter circuit and a hardware zeroing circuit module. The IV conversion circuit selects two OPA227 operational amplifiers and a precise metal film resistor to form a conversion amplification circuit, the signal amplification filter circuit adjusts the precise amplification factor by the slide rheostat, the OPA227 forms a reverse circuit, the capacitor performs filter optimization, and the hardware zeroing circuit module is respectively formed by the two OPA227 operational amplifiers, one slide rheostat and four resistors forming the operational circuit.

The schematic diagram of the IV conversion circuit is shown in fig. 16, and the microprocessor can only recognize the voltage signal, so that the voltage signal needs to be converted into the voltage signal after the reaction current is input, so that the microprocessor can recognize the voltage signal. The current is converted into the voltage at two ends of R28, a resistor with a resistance value of 1M is used as R28, the potentials at two ends of the resistor are respectively V1 and V2, and the VR3 value is I.times.R28. The subsequent circuit is composed of a voltage follower circuit and a differential amplifying circuit, and the effect of the circuit is to obtain higher common mode rejection ratio and signal-to-noise ratio, so that the signal anti-interference capability is stronger. The differential amplifying circuit is composed of R24, R25, R35 and R36. Since the output of the differential amplifier is determined by the resistance values of the four resistors, the impedance interference of the input end needs to be isolated, and the output impedance of the OPA227 is close to 0 and close to infinity is utilized as a voltage follower to follow the input signal. And V2 is led out from the output end of U17, and its output impedance is also close to 0. The output voltage of the circuit is V2-V1.

The schematic diagram of the signal amplifying and filtering circuit is shown in fig. 17, because the current direction passes from V1 to R28 to V2, the potential of V1 is higher than V2, and according to the calculation formula of the current-converting voltage circuit, the output voltage is negative, and the main control chip can only recognize positive values, so that the signal needs to be reversely processed, and a reverse amplifying circuit is added in the following circuit design to change the voltage into positive values.

The schematic diagram of the hardware zeroing circuit is shown in fig. 18, and the detected voltage obtained by the previous processing circuit is about tens to hundreds of millivolts, although the detected voltage is not large, when no reaction is added, an initial voltage which is irrelevant to the reaction may occur due to external factors such as electrode replacement, temperature change and the like, and the initial voltage is in the range of 10 mV-3.3V, so that errors are caused to our measurement. In order to allow each experiment to start from the same zero point, a zero setting circuit needs to be designed. The circuit is essentially the same as the current-to-voltage conversion circuit described above, and is a differential amplifier circuit that performs subtraction by different inputs at both ends and outputs the result. Since the differential amplifier requires zero internal resistance of the input signal source, according to the characteristic that the output impedance of the operational amplifier is equivalent to infinity, OPA227 is used as U1, the reference voltage Vref designed before is followed, and the purpose of using a voltage follower has been described above, in order to match the impedance, after the sliding rheostat adjusts the voltage, the voltage divided by Vref on the sliding rheostat is followed by U1 and output to the U3 inverting input terminal. U3 is used as the core of the subtracting circuit, and the signals of the two input ends are subtracted. VO2 is the previously processed signal that has been output by the output of the op-amp, so no voltage follower is added and VO2 is input to the positive input of U3.

The display module U adopts 1602 liquid crystal display screen as display of measurement result. The display screen is small in size and convenient to use, and accords with the portable and miniaturized standard of the design. A schematic diagram of the liquid crystal circuit is shown in fig. 11.

The key module W includes four keys for man-machine interaction, as shown in fig. 12.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that modifications and improvements can be made by those skilled in the art without departing from the structure of the present utility model, and these do not affect the effect of the implementation of the present utility model and the utility of the patent.

Claims (10)

1. An electrochemical detector is characterized by comprising a main control chip module (A), a constant potential control module (B) and a micro-fluidic chip (C); the main control chip module (A) is connected with the control end of the constant potential control module (B); the microfluidic chip (C) comprises an electrode plate (D) and a bonding sheet (E) positioned at the top of the electrode plate (D), the electrode plate (D) comprises a first carrier, a first reaction tank (F), a second reaction tank (G), a counter electrode (H) and a reference electrode (I) are respectively arranged at the top of the first carrier, a first working electrode (J) is arranged in the first reaction tank (F), a second working electrode (K) is arranged in the second reaction tank (G), the first working electrode (J) and the second working electrode (K) share the counter electrode (H) and the reference electrode (I), the bonding sheet (E) comprises a second carrier, a first detection area (L) which corresponds to the first reaction tank (F) in position and is communicated, a second detection area (M) which corresponds to the second reaction tank (G) in position and is communicated, the first detection area (L) and the second detection area (M) are mutually separated, a first reaction substance is arranged in the first detection area (L), and a second reaction substance is arranged in the second detection area (M); the output end of the counter electrode of the constant potential control module (B) is connected with the counter electrode (H), the output end of the reference electrode of the constant potential control module (B) is connected with the reference electrode (I), and the main control chip module (A) is connected with the first working electrode (J) and the second working electrode (K).

2. An electrochemical detector according to claim 1, characterized in that the first carrier is a hydrophobic cloth and the second carrier is a nonwoven, the first detection zone (L) and the second detection zone (M) being separated from each other by a hydrophobic ink (O).

3. An electrochemical detector according to claim 1, characterized in that the first working electrode (J) and the second working electrode (K) are each provided with a circular portion (P), the counter electrode (H) is provided with a first annular portion (Q) corresponding to the circular portion (P) of the first working electrode (J) and the second working electrode (K), respectively, the reference electrode (I) is provided with a second annular portion (R) corresponding to the circular portion (P) of the first working electrode (J) and the second working electrode (K), respectively, and the first annular portion (Q) and the second annular portion (R) are located on both sides of the corresponding circular portion (P).

4. An electrochemical detector according to claim 2, characterized in that the microfluidic chip (C) further comprises a bottom plate (S) for mounting the electrode sheet (D), the bonding sheet (E).

5. An electrochemical detector according to claim 4, characterized in that the base plate (S) is a PVC sheet, and the electrode sheet (D), the bonding sheet (E) are glued on top of the base plate (S).

6. An electrochemical detector according to claim 1, wherein the first reactant is a glucose reactant and the second reactant is a uric acid reactant.

7. The electrochemical detector according to claim 1, further comprising a signal processing optimization module (T), wherein the first working electrode (J) and the second working electrode (K) are connected to the main control chip module (a) through the signal processing optimization module (T).

8. The electrochemical detector according to claim 1, further comprising a display module (U), a storage module (V), and a key module (W), wherein the main control chip module (a) is connected to the display module (U), the storage module (V), and the key module (W), respectively.

9. The electrochemical detector according to claim 1, wherein the main control chip module (a) is an STM32 system single chip microcomputer.

10. An electrochemical detector according to claim 8, characterized in that the display module (U) is an LCD1602 liquid crystal display and the storage module (V) is a FLASH memory.