CN113418971B - Electrochemical sensor based on micro-nano ultrasonic robot - Google Patents

Electrochemical sensor based on micro-nano ultrasonic robot Download PDF

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CN113418971B
CN113418971B CN202110583184.9A CN202110583184A CN113418971B CN 113418971 B CN113418971 B CN 113418971B CN 202110583184 A CN202110583184 A CN 202110583184A CN 113418971 B CN113418971 B CN 113418971B
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micro
ultrasonic robot
nano
nano ultrasonic
robot
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CN113418971A (en
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芦小龙
赵聪
魏莹
欧欢
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28Electrolytic cell components
    • G01N27/30Electrodes, e.g. test electrodes; Half-cells
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28Electrolytic cell components
    • G01N27/30Electrodes, e.g. test electrodes; Half-cells
    • G01N27/327Biochemical electrodes, e.g. electrical or mechanical details for in vitro measurements

Abstract

The invention discloses an electrochemical sensor based on a micro-nano ultrasonic robot, which mainly comprises: a micro-nano ultrasonic robot, an electrochemical sensing electrode and a piezoelectric transducer. The piezoelectric transducer excites the whole sensor to vibrate at ultrasonic frequency, and a specific sound flow field is generated in the micro-channel. The micro-nano ultrasonic robot generates forward power by utilizing the vibration of bubbles in an acoustic flow field, further performs large-stroke motion in a three-dimensional space in a liquid medium to capture dispersed target substances, and then enriches on the surface of an electrochemical sensing electrode to cause the change of an electrical signal, so that the ultra-sensitive detection of the target substances in the liquid medium is realized. According to the invention, the micro-nano ultrasonic robot is introduced into the electrochemical sensor, so that the active enrichment effect of the micro-nano ultrasonic robot on the detection target object is emphasized, and the micro-nano ultrasonic robot has the advantages of high sensitivity, low detection lower limit and wide application range.

Description

Electrochemical sensor based on micro-nano ultrasonic robot
Technical Field
The invention belongs to the field of micro-nano robot application, relates to the field of electrochemical sensing, and particularly relates to an electrochemical sensor based on a micro-nano ultrasonic robot.
Background
The immunosensing technology is a relatively hot technology for detecting target bacteria, ions and proteins in the current research, is a high combination of biological immunology, optics and electrochemical technology, and realizes detection by using the impedance, mass and surface structure change generated after the antibody and antigen on the surface of a sensor are combined and by using an optical or electrochemical principle. The electrochemical biosensor technology is one kind of immunosensor technology, and the electrochemical biosensor technology utilizes electrochemical and immunological principles to realize detection of target bacteria or other target substances, and compared with other technologies, the electrochemical biosensor technology has higher integration level and stronger detection capability. The electrochemical biosensors used in general can be classified into an impedance type, an amperometric type and an enzyme immune type, and the impedance type sensor is generally used for detecting bacteria, and the amperometric type and the enzyme immune type sensor are generally used for detecting ions and proteins.
The prior electrochemical biosensor is found by searching the prior related documents, and the concentration of a target substance in a solution is determined by modifying the surface of an electrochemical sensing electrode through biology, so that the electrochemical biosensor is specifically combined with the target substance in the solution, and the electrical signal of the surface of the electrode is changed. For example, in the electrochemical impedance biosensor disclosed in chinese patent application publication No. CN111912976a, the CD44 aptamer modified on the surface of the gold electrode can improve the detection sensitivity of CD44 tumor cells to a certain extent, but the method can only capture a part of cells by means of passive diffusion, and it is difficult to realize active capture of cells in a three-dimensional space, so the detection sensitivity and the lower limit of detection of the sensor are not high. The invention patent of China with the publication number of CN107144603B discloses an impedance type electrochemical biosensor based on electrostatic interaction, which is characterized in that SH-DNA is modified on a gold electrode, then polypeptide containing lysine is modified on the gold electrode, and the polypeptide containing lysine is converted between neutral and positive electricity by utilizing histone acetylase and histone deacetylase, so that the polypeptide is separated from and adsorbed on the surface of the electrode to cause impedance change, and the detection of the histone acetylase and the histone deacetylase is realized. The invention discloses a composite material modified acetylene black carbon paste electrode for measuring the content of triclosan, which is disclosed in the Chinese patent with the publication number of CN111551595B, the composite material modified acetylene black carbon paste electrode is used as a working electrode, a platinum wire electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, a linear voltammetry method is adopted, and an electrochemical sensor for triclosan is constructed according to the relation between the measured oxidation current signal value and the concentration of an object to be measured, so that the rapid analysis and measurement of triclosan are realized.
In the aspect of micro-nano robots, researchers have prepared micro-nano robots in various forms such as rigidity, flexibility, spheres, tubes, spirals and the like through long-term efforts, and invented various driving control modes such as an optical field, a magnetic field, an ultrasonic field, chemical bubbles and the like, but the modes such as optical driving, magnetic field driving and the like generally have the defects of low driving speed or large volume of external auxiliary equipment and the like.
Therefore, the capture and enrichment functions of the micro-nano ultrasonic robot are utilized, the existing electrochemical biosensor is improved, the sensitivity and the detection limit of the electrochemical biosensor are improved, and the practical significance and the practical value are obvious. The biocompatible iron-manganese dioxide system micro-nano robot disclosed in the Chinese invention patent application with the publication number of CN111082705A can be driven by ultrasonic bubbles and can be used as a carrier of a target substance; the ultrasonic precise microfluidic device based on the micro-nano ultrasonic robot array disclosed in the Chinese patent application with the publication number of CN111774105A has obvious reference significance for micro-nano ultrasonic robot control and sensor carrier design.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an electrochemical sensor based on a micro-nano ultrasonic robot, and solves the problems of low sensitivity, insufficient detection limit and the like of the electrochemical sensor used in the prior art. According to the invention, a micro-nano ultrasonic robot is introduced into the existing electrochemical sensor, and the sensitivity and the lower detection limit of the electrochemical sensor are remarkably improved by utilizing the active capture and enrichment effect of the micro-nano ultrasonic robot on a target substance.
The invention also provides a detection platform with the electrochemical sensor.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
an electrochemical sensor based on a micro-nano ultrasonic robot comprises: the device comprises a substrate, a cover plate covering the upper surface of the substrate, a piezoelectric transducer positioned on the lower surface of the substrate, piezoelectric transducer electrodes connected with two ends of the piezoelectric transducer, a micro-nano ultrasonic robot and an electrochemical sensing electrode; the cover plate is provided with a hollow micro-channel, and the two ends of the micro-channel are internally provided with the front ends of the two electrochemical sensing electrodes respectively; the micro-nano ultrasonic robot is positioned in the micro-channel;
the piezoelectric transducer is used for generating high-frequency micro-amplitude vibration so as to drive the whole sensor to vibrate at an ultrasonic frequency and generate a specific sound flow field in the micro-channel; the method comprises the steps of enabling a substrate to be decomposed by catalyst components contained in the micro-nano ultrasonic robot to generate bubbles, controlling the micro-nano ultrasonic robot to move in a three-dimensional space in a liquid medium by utilizing vibration of the bubbles in an acoustic flow field so as to capture target substances dispersed in the liquid medium, and then controlling the micro-nano ultrasonic robot with the captured target substances to be enriched on the surface of an electrochemical sensing electrode to cause changes of an electrical signal on the electrochemical sensing electrode so as to determine the concentration of the target substances in the liquid medium.
Further, printing an electrochemical sensing electrode on the substrate in a screen printing mode, adhering a cover plate, and processing a micro-channel on the cover plate by a micro-pouring process; injecting biological body fluid into the micro flow channel; the micro-nano ultrasonic robot is dispersed in the micro-channel, and capture, transportation and enrichment of micro-particles are realized by utilizing ultrasonic vibration.
Furthermore, the substrate is made of quartz glass or silicon wafers; the cover plate is made of organic glass or organic silicon rubber.
Further, the electrochemical sensing electrode adopts a three-electrode system and comprises a Counter Electrode (CE), a Working Electrode (WE) and a Reference Electrode (RE).
Furthermore, the micro flow channel comprises two reservoirs, the two reservoirs are respectively used for accommodating a front-end Reference Electrode (RE), a printing Counter Electrode (CE) and a Working Electrode (WE) of the electrochemical sensing electrodes at two ends, and a middle channel communicated with the two reservoirs is further arranged.
Further, the micro-nano ultrasonic robot is of a multilayer hollow tubular structure, and the outermost layer of the micro-nano ultrasonic robot is subjected to functional modification to capture a target substance.
Further, the electrochemical sensing electrode realizes the measurement of the concentration of various target substances by increasing the number of working electrodes and sharing the reference electrode and the counter electrode.
Furthermore, the electrochemical sensing electrode is printed in an interdigital mode so as to increase an enrichment area of the micro-nano ultrasonic robot.
Furthermore, different kinds of sensitive substances are fixed on the surface of the electrochemical sensing electrode and used for measuring the concentration of different kinds of target substances.
The invention relates to an electrochemical sensor based on a micro-nano ultrasonic robot, which is realized by combining the capturing and enriching effects of the micro-nano ultrasonic robot on a target substance and a measuring method of an electrochemical sensor, overcomes the defects of low sensitivity and insufficient detection lower limit of the traditional electrochemical sensor, and realizes the purpose of quickly, efficiently and accurately measuring the concentration of the target substance in a solution, and comprises the following steps:
firstly, an excitation signal generated by a signal generator or a computer is amplified by a power amplifier, and then the piezoelectric transducer is driven to vibrate by utilizing the inverse piezoelectric effect of a piezoelectric material, so that the whole sensor is driven to vibrate, and a specific acoustic flow field is generated in a micro-channel. Meanwhile, the micro-nano ultrasonic robot in the micro-channel performs large-stroke motion in a three-dimensional space in a reservoir of the micro-channel under specific frequency to capture target substances in the solution. After the capture is completed, the ultrasonic frequency is changed, and the micro-nano ultrasonic robot is controlled to be enriched on the surface of the electrochemical sensing electrode, so that the change of the electrical signal on the electrochemical sensing electrode is caused. The concentration of the target substance in the solution can be determined by the change of the electrical signal by an externally integrated electrochemical analysis instrument.
The invention has the following beneficial effects:
1. firstly, the specific capture and enrichment effect of the micro-nano ultrasonic robot on the target substance is applied to the electrochemical sensor, so that the target substance in a three-dimensional space is enriched to the electrochemical sensing electrode, and the sensitivity and the detection lower limit of the electrochemical sensor are greatly improved.
2. Secondly, the sensor can realize rapid measurement and is convenient for miniaturization by utilizing the characteristics of high motion speed of the micro-nano ultrasonic robot and simple external auxiliary equipment.
3. The micro-nano ultrasonic robot can be combined with different target substances by functional modification to measure the concentration of different types of target substances; the shape of the electrochemical sensing electrode can be flexibly designed, and the concentration of various target substances can be measured by increasing the number of working electrodes and sharing the reference electrode and the counter electrode; by designing the microchannel in a multi-reservoir fashion, multiple measurements can be made, and the sensor in the example can measure twice. Therefore, the sensor has wide application range and flexible and various design.
4. The working electrode and the reference electrode can be designed into an interdigital type, so that the enrichment area of the micro-nano ultrasonic robot is increased, and ultrahigh-sensitivity detection is carried out.
Drawings
Fig. 1 (a) is a three-dimensional structure diagram (front side) of an electrochemical sensor of an integrated micro-nano ultrasonic robot;
fig. 1 (b) is a three-dimensional structure diagram (back side) of an electrochemical sensor of an integrated micro-nano ultrasonic robot;
FIG. 1 (c) is an exploded view of an electrochemical sensor structure of an integrated micro-nano ultrasonic robot;
FIG. 2 (a) is a schematic diagram of an electrochemical sensor electrode comprising a micro-nano robot;
FIG. 2 (b) is a schematic diagram of an electrochemical sensor electrode capable of detecting two substances (left) and three substances (right)
FIG. 3 is a schematic diagram of capture and transportation of bacteria by a specific protein modified micro-nano ultrasonic robot;
FIG. 4 (a) is a schematic diagram of a micro-nano ultrasonic robot in a three-dimensional reservoir for capturing bacteria in a solution;
FIG. 4 (b) is a schematic diagram of enrichment of a micro-nano ultrasonic robot capturing bacteria to the vicinity of a working electrode and a reference electrode;
FIG. 5 is a model of an equivalent circuit between electrodes when an electrolyte solution and bacteria are used as impedances;
FIG. 6 is a schematic diagram of interdigital electrodes for ultra-high sensitivity detection;
in the figure, 1 is a substrate; 2 is a silicone rubber cover plate; 3, a micro-nano ultrasonic robot; 4 is an electrochemical sensing electrode; 5 is a piezoelectric transducer; 6 is piezoelectric transducer electrode; 7 is a Counter Electrode (CE); 8 is a Working Electrode (WE); 9 is a Reference Electrode (RE); 10 is a target bacterium; 11 is a specific protein; 12 is a bubble; 21 is a micro-channel structure; 22 is a reservoir; 23 is a middle channel; and 41 is an electrode access end.
Detailed Description
The present invention will be further described with reference to the following examples and drawings for the convenience of those skilled in the art, and the description of the embodiments is not intended to limit the present invention.
An electrochemical sensor based on a micro-nano ultrasonic robot comprises the following specific implementation modes:
as shown in fig. 1 (a), 1 (b) and 1 (c), the invention discloses an electrochemical sensor based on a micro-nano ultrasonic robot, which comprises a substrate 1, a silicone rubber cover plate 2, a micro-nano ultrasonic robot 3, an electrochemical sensing electrode 4, a piezoelectric transducer 5 and a piezoelectric transducer 6. The substrate 1 is made of quartz glass and has the size of 20 multiplied by 8 multiplied by 0.5mm; the cover plate 2 is made of organic silicon rubber and has the size of 14 multiplied by 8 multiplied by 0.3mm; the piezoelectric transducer 5 is a piezoelectric ceramic piece made of PZT-8 with the size of phi 6 multiplied by 0.5mm; the micro-nano ultrasonic robot 3 adopts a biocompatible iron-manganese dioxide system micro-nano robot disclosed in the Chinese invention patent application with the publication number of CN 111082705A; the electrochemical sensing electrode 4 and the piezoelectric transducer electrode 6 are printed on the substrate by screen printing. When the piezoelectric ceramic plate is installed, the piezoelectric ceramic plate 6 is pasted at the center below the quartz substrate 1, and a conducting wire is respectively led out from the front side and the back side of the piezoelectric ceramic plate 5 by using conductive silver adhesive and respectively used as a signal input end and a grounding end to be connected with the piezoelectric transducer electrode 6; the organic silicon rubber cover plate 2 with the hollow micro-channel 21 is adhered above the quartz substrate 1, and the printed electrochemical sensing electrode 4 is aligned with the reservoir 22 of the micro-channel 21, so that the Reference Electrode (RE) 9, the printed Counter Electrode (CE) 7 and the Working Electrode (WE) 8 at the front end of the electrochemical sensing electrode 4 are positioned in the center of the reservoir 22. In this embodiment, the reservoir 22 is a circular opening. The micro flow channel structure 21 has two reservoirs 22 for respectively accommodating a front Reference Electrode (RE) 9, a printed Counter Electrode (CE) 7 and a Working Electrode (WE) 8 of the electrochemical sensing electrodes 4 at both ends, and further has a middle channel 23 communicating the two reservoirs 22.
When the micro-nano ultrasonic micro-channel reservoir structure is used, firstly, a solution containing bacteria to be detected is gently dripped into the micro-channel reservoir 22, the whole micro-channel structure 21 is filled with the solution by utilizing capillary force, and the prepared micro-nano ultrasonic robot 3 is added into the reservoir 22. Then, an alternating voltage of a specific frequency (generally, a high-frequency mode) is applied to the piezoelectric transducer 5. Under the voltage, the micro-nano ultrasonic robot 3 modified by the specific protein 11 can make large-stroke motion in the three-dimensional storage layer to actively capture the target bacteria 10 in the storage layer. After the capture is finished, changing the alternating voltage frequency to another specific value (generally a low-frequency mode), wherein under the frequency, the micro-nano ultrasonic robot carrying the target bacteria finishes the enrichment near the electrochemical sensing electrodes 4, which can cause the impedance change between the two electrochemical sensing electrodes 4; the impedance change can be measured by an electrochemical analyzer in the prior art, and the concentration of the target bacteria is obtained by the analysis of professional software matched with the electrochemical analyzer; in this embodiment, the result of obtaining the target bacterial concentration can be achieved by using the electrochemical workstation CHI660E of shanghai chenhua company and the detection software of the computer end thereof, which is not described herein again.
When the electrochemical sensing electrode 4 is printed on the silicon substrate, a Reference Electrode (RE) 9 and an electrode access terminal 41 (a part connected with an electrochemical analyzer) are printed on the corresponding position of the silicon substrate 1 by Ag/AgCl ink, and are cured for 20 minutes in an oven at 85 ℃; the Counter (CE) 7 and Working (WE) 8 electrodes were then printed with carbon ink at the respective locations, connected to the electrode access 41, and cured in an oven at 85 ℃ for 20 minutes. The printed electrochemical sensing electrode 4 generally adopts a single working electrode three-electrode system, as shown in fig. 2 (a); in special cases where it is desired to measure the concentration of multiple target species, a multi-Working Electrode (WE) 8 may be printed, as shown in fig. 2 (b).
The piezoelectric transducer electrode 6 is printed in the same way as the reference electrode (CE) 9.
When the organic silicon rubber cover plate 2 is prepared, firstly, a relief micro-pattern is processed on a silicon substrate 1 by utilizing a photoetching technology, an anti-sticking agent is coated, then, polydimethylsiloxane (PDMS) and a curing agent are uniformly mixed according to the proportion of 10, then, the mixture is poured on the surface of a template, the template is placed in a vacuum environment until no bubbles visible to naked eyes exist, then, the template is solidified for 1 hour in a baking oven at the temperature of 60 ℃, and after the template is taken out, the organic silicon rubber cover plate 2 printed with the relief pattern is manually stripped.
When assembling the organic silicon rubber cover plate 2, firstly carrying out plasma oxidation irradiation on the binding surface of the organic silicon rubber to improve the binding property, and then binding the cover plate 2 with the upper surface of the quartz substrate 1 to complete sealing. The cover 2 is assembled to ensure that the reservoir 22 contains the front ends of the printed electrochemical sensing electrodes 4 and to try to center the front ends of the electrochemical sensing electrodes 4 in the reservoir.
When the piezoelectric ceramic piece 5 is pasted, a proper amount of conductive silver adhesive is taken from the tube A and the tube B, 1:1 is fully mixed, a proper amount of mixed conductive silver adhesive is taken and uniformly coated on one side of the piezoelectric ceramic piece 5, then the piezoelectric ceramic piece is pasted on the corresponding position of the quartz substrate 1, proper pressure is applied by a bench clamp for pressing, and then the piezoelectric ceramic piece is heated in an oven at 60 ℃ for 1.5 hours. And conductive silver adhesive is used for leading out a lead from the front surface and the back surface of the piezoelectric ceramic piece 5 respectively, and the lead is used as a signal input end and a grounding end to be connected with the piezoelectric transducer electrode 6.
The preparation of the biocompatible iron-manganese dioxide system micro-nano ultrasonic robot 3 can be divided into the following steps: (1) Carrying out electrochemical deposition of the polyethylene dioxythiophene support outer layer, wherein the deposition time is 100-130s; (2) Performing electrochemical deposition of the Fe intermediate layer on the basis of the polyethylene dioxythiophene support outer layer prepared in the first step, wherein the deposition time is 40-70s; (3) Applying an ultrasonic field, and performing MnO on the basis of the polyethylene dioxythiophene support outer layer and the Fe intermediate layer obtained in the step two 2 Electrochemical deposition of the inner layer, wherein the deposition time is 30-70s; (4) The outer layer containing the polyethylene dioxythiophene obtained in the step three, the middle layer containing Fe and MnO 2 And polishing, dissolving and centrifuging the polycarbonate film of the inner layer to obtain the tubular micro-nano ultrasonic robot. After the tubular micro-nano ultrasonic robot 3 is prepared, the outer surface of the tubular micro-nano ultrasonic robot needs to be functionally modified, and the specific modification content depends on target bacteria.
Fig. 3 is a schematic diagram illustrating capture and transportation of target bacteria by a functionalized micro-nano ultrasonic robot, wherein on one hand, in a solution, a catalytic layer of the micro-nano ultrasonic robot 3 catalyzes the solution to generate bubbles 12 at the tail of the micro-nano ultrasonic robot 3; on the other hand, under ultrasonic excitation, the micro-nano ultrasonic robot 3 is driven by bubble vibration to move in the solution, and the target bacteria 10 dispersed in the solution are captured by specific protein and transported to a designated position.
Fig. 4 (a) is a schematic diagram of capturing target bacteria 10 in a solution by the micro-nano ultrasonic robot 3 in a three-dimensional reservoir, and fig. 4 (b) is a schematic diagram of enriching the target bacteria 10 captured by the micro-nano ultrasonic robot 3 to the vicinity of a Working Electrode (WE) 8. Firstly, the excitation frequency of the piezoelectric transducer 5 is adjusted to a specific value (generally, a high-frequency mode), the micro-nano ultrasonic robot 3 is controlled to make a large-stroke motion in the three-dimensional reservoir, and the target bacteria 10 dispersed in the reservoir 22 are fully captured. Then, the excitation frequency of the piezoelectric transducer 5 is adjusted to another specific value (generally, a low-frequency mode), and the dispersed micro-nano ultrasonic robot 3 enriches the bacteria of the transportation target 10 to the vicinity of the Working Electrode (WE) 8 and the Reference Electrode (RE) 9, so as to cause the impedance change between the two electrochemical sensing electrodes 4. The mode makes up the defect that the traditional impedance type electrochemical biosensor can only capture target bacteria in a limited range by a passive diffusion mode, and can obviously improve the sensitivity and the lower detection limit of the sensor.
FIG. 5 is a diagram showing a model of an equivalent circuit between electrodes when an electrolyte solution and bacteria are used as impedances, wherein C PAR Represents the parasitic capacitance, R, generated at the phase interface SOL And C SOL Respectively, the resistance and capacitance of the electrolyte solution, R BCM And C BCM Respectively, the resistance and capacitance of the bacterial cell membrane, R CYT Representing the resistance of the bacterial cytoplasm. When a large number of bacteria are distributed between the working electrode and the counter electrode, the impedance between the electrodes changes significantly due to the capacitance of the cell membrane, the resistance of the cell membrane, and the resistance of the cytoplasm of the cell membrane.
Fig. 6 is a schematic diagram of an interdigital electrode for ultra-high sensitivity detection. When the target bacteria concentration is detected, the Working Electrode (WE) and the Counter Electrode (CE) can be designed into an interdigital shape as shown in figure 6, so that the enrichment area of the micro-nano ultrasonic robot can be greatly increased, and ultrahigh sensitivity detection can be carried out.
The specific application routes of the present invention are many, the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, improvements may also be made on the micro-nano ultrasonic robot type and surface functionalization method, the electrochemical sensing electrode surface functionalization method, and the electrochemical detection method without departing from the active enrichment principle of the micro-nano ultrasonic robot, and these improvements should also be regarded as the protection scope of the present invention.

Claims (9)

1. An electrochemical sensor based on a micro-nano ultrasonic robot is characterized by comprising: the device comprises a substrate, a cover plate covering the upper surface of the substrate, a piezoelectric transducer positioned on the lower surface of the substrate, piezoelectric transducer electrodes connected with two ends of the piezoelectric transducer, a micro-nano ultrasonic robot and an electrochemical sensing electrode; the cover plate is provided with a hollow micro-channel, and the two ends of the micro-channel are respectively accommodated with the front ends of the two electrochemical sensing electrodes; the micro-nano ultrasonic robot is positioned in the micro-channel;
the piezoelectric transducer is used for generating high-frequency micro-amplitude vibration so as to drive the whole sensor to vibrate at an ultrasonic frequency and generate a specific sound flow field in the micro-channel; the method comprises the steps of enabling a substrate to be decomposed by catalyst components contained in the micro-nano ultrasonic robot to generate bubbles, controlling the micro-nano ultrasonic robot to move in a three-dimensional space in a liquid medium by utilizing vibration of the bubbles in an acoustic flow field so as to capture target substances dispersed in the liquid medium, and then controlling the micro-nano ultrasonic robot with the captured target substances to be enriched on the surface of an electrochemical sensing electrode to cause changes of an electrical signal on the electrochemical sensing electrode so as to determine the concentration of the target substances in the liquid medium.
2. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein an electrochemical sensing electrode is printed on a substrate in a screen printing mode, a cover plate is pasted on the substrate, and a micro channel is processed on the cover plate through a micro pouring process; injecting biological body fluid into the micro flow channel; the micro-nano ultrasonic robot is dispersed in the micro-channel, and capture, transportation and enrichment of micro-particles are realized by utilizing ultrasonic vibration.
3. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein the substrate is made of quartz glass or silicon wafer; the cover plate is made of organic glass or organic silicon rubber.
4. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, 2 or 3, wherein the electrochemical sensing electrode adopts a three-electrode system and comprises a counter electrode, a working electrode and a reference electrode.
5. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein the micro flow channel comprises two reservoirs, the two reservoirs are respectively used for accommodating front reference electrodes, printed counter electrodes and working electrodes of electrochemical sensing electrodes at two ends, and a middle channel for communicating the two reservoirs is further provided.
6. The electrochemical sensor based on the micro-nano ultrasonic robot is characterized in that the micro-nano ultrasonic robot is of a multilayer hollow tubular structure, and the outermost layer of the micro-nano ultrasonic robot is functionally modified to capture a target substance.
7. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein the electrochemical sensing electrode is used for measuring the concentration of multiple target substances by increasing the number of working electrodes and sharing a reference electrode and a counter electrode.
8. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein the electrochemical sensing electrode is printed in an interdigital manner to increase an enrichment area of the micro-nano ultrasonic robot.
9. The micro-nano ultrasonic robot-based electrochemical sensor according to claim 1, wherein different types of sensitive substances are fixed on the surface of the electrochemical sensing electrode for measuring the concentration of different types of target substances.
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