CN112666243A - Optical addressing square wave/alternating current volt-ampere electrochemical sensing system and method - Google Patents

Abstract

The invention discloses a light addressing square wave/alternating current volt-ampere electrochemical sensing system and a method, a semiconductor chip is fixed at the lower end of a detection cell device, a through hole containing cavity is arranged on the detection cell device, a counter electrode and a reference electrode of the electrochemical detection device are arranged in detection liquid at intervals, a working electrode of the electrochemical detection device is electrically connected with the lower end of the semiconductor chip, constant laser is adopted to irradiate a specific position of the semiconductor chip with a field effect structure to excite and generate in-situ photon-generated carriers, simultaneously, the external voltage of the semiconductor chip is modulated by utilizing the SWV or ACV function of an electrochemical workstation to influence the directional migration and diffusion process of the photon-generated carriers, so that in-situ photocurrent is obtained by external circuit detection, the detection of the pH value of a solution and the in-situ detection and imaging of the surface impedance of the chip can be realized, compared with the traditional electrochemical analysis method, provides a new solution for high-throughput multi-site electrochemical detection.

Description

Optical addressing square wave/alternating current volt-ampere electrochemical sensing system and method

Technical Field

The invention belongs to the photoelectric chemical sensing and imaging technology, and particularly relates to a light-addressable square wave/alternating current volt-ampere electrochemical sensing system and method.

Background

Square Wave Voltammetry (SWV) is a method in which a square wave voltage with a large amplitude is superposed on a step voltage for rapid scanning, and the difference between the currents at the last stage of a positive half cycle and the last stage of a negative half cycle of the square wave is recorded, so that the charging current is well eliminated, and a current-potential voltammogram can be recorded in a short time. Alternating Current Voltammetry (ACV) is to apply a dc potential which is scanned slowly with time to a working electrode, superimpose a sine wave ac component, measure the amplitude and corresponding phase angle of the ac component of the current, and obtain a corresponding ac voltammogram. The two methods have the characteristics of multiple functions, high sensitivity and high efficiency, and are widely applied to quantitative analysis and kinetic research of substances. However, conventional SWV and ACV electrical analysis methods do not have spatial resolution, reflect the whole information of the detected sample by using the average result of electrode measurement, are difficult to meet the requirements of high-flux and multi-site detection and sensing, and cannot perform two-dimensional imaging on the detected sample.

Disclosure of Invention

The invention provides an addressable square wave/alternating current volt-ampere electrochemical sensing and imaging method, which realizes sensing and detection of surface potential and system impedance with spatial resolution capability and overcomes the defect that the conventional electrochemical detection technology lacks spatial resolution capability.

In order to achieve the purpose, the invention adopts the following technical scheme:

a light addressing square wave/alternating current volt-ampere electrochemical sensing system comprises a laser device, a semiconductor chip, a detection cell device, an electrochemical detection device, a displacement device and an optical imaging device; the semiconductor chip is fixed in the lower extreme of detection cell device, be equipped with the through-hole on the detection cell device and hold the chamber, the through-hole holds the intracavity and is used for placing detection liquid, it can with the semiconductor chip up end contact to detect liquid, electrochemistry detection device's counter electrode and reference electrode interval are placed in detecting liquid, electrochemistry detection device's working electrode is connected with semiconductor chip lower extreme electricity, laser device and optical imaging device set up in detection cell device upper end, optical imaging device's light source and laser device's laser can shine on semiconductor chip upper surface through the through-hole appearance chamber, semiconductor chip and detection cell device are fixed in on the displacement device.

Furthermore, the electrochemical detection device comprises an electrochemical workstation, a counter electrode, a reference electrode and a working electrode, wherein the counter electrode, the reference electrode and the working electrode are all connected with the electrochemical workstation, the electrodes adopt platinum wires, the reference electrode adopts an Ag/AgCl reference electrode, and the working electrode is connected with the semiconductor chip.

Furthermore, the laser device comprises a laser controller, a laser, a collimating lens, a beam splitter prism and an amplifying objective lens, wherein the amplifying objective lens is arranged at the upper end of the detection cell device, the collimating lens is arranged at the laser emitting end of the laser, the beam splitter prism is arranged between the collimating lens and the amplifying objective lens, and the laser is connected with the laser controller.

Furthermore, the optical imaging device comprises an LED illumination light source, a field lens and a CCD camera, the CCD camera is connected with a computer, the computer is used for acquiring and storing images, the field lens is arranged on one side of the beam splitter prism, and the field lens, the beam splitter prism and the magnifying objective lens are arranged on the same straight line.

Further, the semiconductor chip is a pH sensitive semiconductor chip or an impedance sensitive semiconductor chip.

Further, the pH sensitive semiconductor chip comprises a sensitive layer, an insulating layer, a semiconductor layer and an ohmic contact layer which are sequentially stacked from top to bottom, the ohmic contact layer is electrically connected with a working electrode of the electrochemical detection device and is in contact with electrolyte in the detection cell device, the impedance sensitive semiconductor chip comprises the insulating layer, the semiconductor layer and the ohmic contact layer which are sequentially stacked from top to bottom, the ohmic contact layer is electrically connected with the working electrode of the electrochemical detection device, and the insulating layer is in contact with the electrolyte in the detection cell device.

Furthermore, the detection cell device comprises a detection cavity and an electric connection sheet, wherein the detection cavity is provided with a through hole cavity, the lower end face of the semiconductor chip is in sealing contact with the lower end face of the detection cavity, the electric connection sheet is arranged at the lower end of the semiconductor chip, and the electric connection sheet is electrically connected with the semiconductor chip.

An optically addressed square wave/alternating current voltammetric electrochemical imaging method comprising the steps of:

s1, fixing the detection cell device fixed with the pH sensitive semiconductor chip on the displacement device, and adding buffer salt electrolytes with different pH values into a through hole cavity of the detection cell device; putting a counter electrode and a reference electrode of the electrochemical detection device into electrolyte, and connecting a working electrode with an ohmic contact layer of the pH sensitive semiconductor chip;

s2, adjusting the displacement device to enable the laser generated by the laser to irradiate the upper end of the pH sensitive semiconductor chip through the through hole cavity of the detection cell device, and enabling the laser focus point to be located at the position of 0.8-1.2cm of the surface of the semiconductor;

and S3, sequentially carrying out SWV and ACV electrochemical tests on the solutions with different pH values by adopting an electrochemical workstation to obtain a dark/light current-potential curve, thereby completing addressable square wave/alternating current volt-ampere electrochemical sensing detection.

An optically addressed square wave/alternating current volt-ampere electrochemical sensing method comprises the following steps:

s1, fixing the detection cell device fixed with the impedance sensitive semiconductor chip on the displacement device, and adding electrolyte into the detection cell device; putting a counter electrode and a reference electrode of the electrochemical detection device into electrolyte, and connecting a working electrode with an ohmic contact layer of the impedance sensitive semiconductor chip through an electric connection sheet;

s2, adjusting the displacement device to enable the laser generated by the laser to irradiate the surface of the impedance sensitive semiconductor chip through the through hole cavity of the detection cell device and enable the laser focus point to be positioned on the surface of the semiconductor chip;

s3, sequentially carrying out SWV and ACV electrochemical tests by adopting an electrochemical workstation to respectively obtain I-V curves of the tested SWV and ACV;

s4, adjusting the displacement device, observing through the optical imaging system, enabling the semiconductor chip to perform two-dimensional scanning on a horizontal plane relative to the laser by taking the photoetching pattern as a center, and taking the SWV photocurrent magnitude under the fixed potential of the corresponding coordinate, thereby obtaining the photocurrent distribution image of the photoetching pattern, namely the photoaddressing square wave volt-ampere electrochemical impedance diagram;

further, the displacement device is adjusted to enable the electric semiconductor chip to move linearly relative to the laser in a horizontal direction, SWV scanning is conducted on the edge of the photoetching pattern on the semiconductor chip, so that a current-position curve under a fixed potential is obtained, differential processing is conducted on the current-position curve, and the size of the half-peak width is obtained, namely the size of the spatial resolution of the optical addressing square wave volt-ampere impedance imaging.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention relates to a light-addressable square wave/alternating current volt-ampere electrochemical sensing system, a semiconductor chip is fixed at the lower end of a detection cell device, a through hole containing cavity is arranged on the detection cell device, so that detection liquid can be contacted with the upper end surface of the semiconductor chip to form a detection space, a counter electrode and a reference electrode of an electrochemical detection device are arranged in the detection liquid at intervals, a working electrode of the electrochemical detection device is electrically connected with the lower end of the semiconductor chip, a laser device is arranged at the upper end of the detection cell device, laser of the laser device can irradiate the upper surface of the semiconductor chip through the through hole containing cavity, the semiconductor chip and the detection cell device are fixed on a displacement device, the specific position of the chip is irradiated by the laser, based on SWV and ACV electric analysis means of an electrochemical workstation, addressable detection of the surface potential and system impedance of, simple structure and easy wide application.

The invention relates to a light-addressable square wave/alternating current volt-ampere electrochemical sensing and imaging method, which adopts constant laser to irradiate a specific position of a semiconductor chip with a field effect structure, excites and generates an in-situ photon-generated carrier, and simultaneously modulates the external voltage of the semiconductor chip by utilizing the SWV or ACV function of an electrochemical workstation to influence the directional migration and diffusion process of the photon-generated carrier, thereby obtaining the in-situ photocurrent in an external circuit detection, and realizing the detection of the pH value of a solution and the in-situ detection and imaging of the surface impedance of the chip.

Drawings

Fig. 1 is a schematic structural diagram in an embodiment of the present invention.

FIG. 2 is a schematic view of a test cell device and a semiconductor chip mounting structure according to an embodiment of the present invention.

FIG. 3 is a SWV current-potential I-V curve diagram of a pH sensitive semiconductor chip with and without light in an embodiment of the present invention.

FIG. 4 is a graph of the current-potential I-V of the ACV of the pH sensitive semiconductor chip with and without light according to an embodiment of the present invention.

FIG. 5 is a SWV curve of potential scanning of a pH sensitive semiconductor chip according to an embodiment of the present invention; fig. 5a is a graph of the photo-addressable SWV in buffer solutions withpH 3,4,5,6,7,8,9.2, respectively, and fig. 5b is a graph of the potential as a function of pH at-100 nA constant current.

Fig. 6 is a graph of potential scan ACV of a pH sensitive semiconductor chip in an embodiment of the present invention, fig. 6a is a graph of photo-addressable ACV in buffer solutions withpH 3,4,5,6,7,8, and 9.2, respectively, and fig. 6b is a graph of the linear relationship of potential versus pH at a constant current of 410 nA.

Fig. 7 is a graph of the scanning I-V curve of an optically addressed SWV of an impedance sensitive semiconductor chip in an embodiment of the present invention in areas with SU8 coverage and withoutSU 8.

Fig. 8 is a graph of the scanning I-V of an optically addressed ACV of an impedance-sensitive semiconductor chip in an embodiment of the present invention in an area with SU8 coverage and in an area withoutSU 8.

FIG. 9 is a two-dimensional scan of a focused laser over a SU8 pattern, according to an embodiment of the present invention, and FIG. 9a is an optical image taken by an optical imaging system; FIG. 9b is a two-dimensional distribution plot of photocurrent obtained from a SWV scan at a potential of-0.8V.

FIG. 10 shows the result of a linear scan of a focused laser at the edge of an SU8 pattern according to an embodiment of the present invention, and FIG. 10a is a plot of SWV current versus position (I-x) at the resulting-0.8V potential; FIG. 10b is the result of evaluating spatial resolution based on SWV current-position (I-x) plots.

Wherein, 1, a laser device; 2. a semiconductor chip; 3. a detection cell device; 4. an electrochemical detection device; 5. a displacement device; 6. a counter electrode; 7. a reference electrode; 8. a working electrode; 9. a sensitive layer; 10. an insulating layer; 11. a semiconductor layer; 12. an ohmic contact layer; 13. a detection cavity; 14. an electrically connecting sheet; 15. a seal ring; 16. a bolt group; 17. an electrochemical workstation; 18. an optical imaging device; 19. a laser controller; 20. a laser; 21. a collimating lens; 22. a beam splitter prism; 23. a magnifying objective lens; 24. an LED illumination light source; 25. a field lens; 26. a computer; 27. a CCD camera.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

as shown in fig. 1, an optical addressing square wave/ac volt-ampere electrochemical sensing system comprises alaser device 1, asemiconductor chip 2, adetection cell device 3, anelectrochemical detection device 4, adisplacement device 5 and anoptical imaging device 18;semiconductor chip 2 is fixed indetection pond device 3 lower extreme, it holds the chamber to be equipped with the through-hole ondetection pond device 3, the through-hole holds the intracavity and is used for placing detection liquid, it can contact withsemiconductor chip 2 up end to detect liquid,electrochemical detection device 4'scounter electrode 6 andreference electrode 7 interval are placed in detecting liquid,electrochemical detection device 4's workingelectrode 8 is connected withsemiconductor chip 2 lower extreme electricity,laser device 1 and optical imaging device set up indetection pond device 3 upper end, optical imaging device's light source andlaser device 1's laser can shine insemiconductor chip 2 upper surface through the through-hole appearance chamber,laser device 1 andoptical imaging device 2 form confocal system,semiconductor chip 2 anddetection pond device 3 are fixed in ondisplacement device 5.

Theelectrochemical detection device 4 includes anelectrochemical workstation 17, acounter electrode 6, areference electrode 7, and a workingelectrode 8. The counter electrode, the reference electrode and the working electrode are connected with an electrochemical workstation and used for SWV and ACV electrochemical detection; the counter electrode adopts a platinum wire, the reference electrode adopts an Ag/AgCl reference electrode, and the working electrode is connected with the semiconductor chip.

Thelaser device 1 comprises alaser controller 19, alaser 20, a collimatinglens 21, abeam splitter prism 22 and an amplifyingobjective lens 23, the amplifyingobjective lens 23 is arranged at the upper end of thedetection cell device 3, the collimatinglens 21 is arranged at the laser emitting end of thelaser 20, thebeam splitter prism 22 is arranged between the collimatinglens 21 and the amplifyingobjective lens 23, the laser is connected with the laser controller and generates laser with the wavelength of 405nm, the laser irradiates the upper surface of the semiconductor chip through the collimatinglens 21, thebeam splitter prism 22, the amplifyingobjective lens 23 and the through hole containing cavity, and the diameter of a light spot is about 10 mu m when the light spot is focused; the magnifyingobjective 23 has a magnification of 10.

The optical imaging device comprises an LEDillumination light source 24, afield lens 25 and aCCD camera 27, the CCD camera is connected with acomputer 26, thecomputer 26 is used for obtaining and storing images, thefield lens 25 is arranged on one side of thebeam splitter prism 22, thefield lens 25, thebeam splitter prism 22 and the magnifyingobjective 23 are arranged on the same straight line, LED illumination light irradiates the upper surface of the semiconductor chip through the through hole containing cavity, and reflected light of the LED illumination light passes through the magnifyingobjective 23, the beam splitter prism, the field lens and the CCD camera to obtain optical images.

Thesemiconductor chip 2 adopts a pH sensitive semiconductor chip or an impedance sensitive semiconductor chip; the pH sensitive semiconductor chip comprises asensitive layer 9, an insulatinglayer 10, asemiconductor layer 11 and anohmic contact layer 12 which are sequentially stacked from top to bottom, wherein theohmic contact layer 12 is electrically connected with a workingelectrode 8 of theelectrochemical detection device 4 to form good contact so as to conduct current, and thesensitive layer 9 is in contact with electrolyte in thedetection cell device 3. The impedance sensitive semiconductor chip comprises an insulatinglayer 10, asemiconductor layer 11 and anohmic contact layer 12 which are sequentially stacked from top to bottom, wherein theohmic contact layer 12 is electrically connected with a workingelectrode 8 of theelectrochemical detection device 4, the insulatinglayer 10 is in contact with an electrolyte in thedetection cell device 3, and the surface of the insulating layer is provided with an SU8 photoresist pattern.

As shown in fig. 2, thedetection cell device 3 includes adetection cavity 13 and anelectrical connection sheet 14, thedetection cavity 13 is provided with a through hole cavity, thesemiconductor chip 2 contacts with the lower end surface of thedetection cavity 13, theelectrical connection sheet 14 is arranged at the lower end of thesemiconductor chip 2, and theelectrical connection sheet 14 is electrically connected with thesemiconductor chip 2; thesemiconductor chip 2 is fixedly connected with thedetection cavity 13 through thebolt group 16, and thesemiconductor chip 2 is clamped between the electric connectingsheet 14 and thedetection cavity 13; specifically, theohmic contact layer 12 of thesemiconductor chip 2 is in contact with theelectrical connection pad 14.

And a sealingring 15 is arranged between thesemiconductor chip 2 and the lower end surface of thedetection cavity 13, and the sealing ring is a silicon rubber sealing ring. Thedetection cavity 13 is made of organic glass. Theelectrical connection sheet 14 is an aluminum sheet.

The pH sensitive semiconductor chip is used for solution pH test,the application adopts the specific structure of the pH sensitive semiconductor chip as follows: (50nm Si)₃N₄) Insulating layer (100nm SiO)₂) -semiconductor layer (p-Si,100,1-10 Ω cm) -ohmic contact (30nm Cr,150nm Au), in which Si₃N₄The ohmic contact is prepared by magnetron sputtering method, SiO₂Is grown by a thermal oxidation method.

The impedance sensitive semiconductor chip is used for impedance imaging, and the specific structure of the impedance sensitive semiconductor chip is adopted in the application as follows: insulating layer self-assembled organic monolayers (SAMs) -semiconductor layer (p-Si,100,1-10 Ω cm) -ohmic contact (30nm Cr,150nm Au), wherein SAMs is an undecylenic acid film grown by a thermally induced silylation method and has a thickness of 1nm, and compared with a conventional silicon oxide insulating layer, the impedance sensitivity of the system can be significantly increased. During electrochemical detection, the sensitive layer of the semiconductor chip faces upwards and is used as a working electrode to be in contact with electrolyte, and SU 82005 photoresist patterns with the thickness of about 5 mu m are prepared on the surface of the insulating layer.

Thedisplacement device 5 adopts a three-dimensional electric displacement system, and thedetection cell device 3 is fixed on an XY plane of the displacement system.

An optically addressed square wave/alternating current volt-ampere electrochemical sensing method comprises the following steps:

s1, cleaning and assembling the semiconductor chip:

step 1, ultrasonically cleaning the semiconductor chip in acetone, isopropanol and pure water for 15min respectively in sequence, and drying the semiconductor chip by using a nitrogen gun for later use.

Step 2, placing the cleaned sensitive layer of the semiconductor chip on an aluminum sheet upwards, placing an organic glass cavity on the semiconductor chip to enable the through hole cavity to be positioned above the chip, fixing thesemiconductor chip 2 and thedetection cavity 13 by utilizing abolt group 16, and sealing thesemiconductor chip 2 and thedetection cavity 13 through a sealingring 15;

and 3, fixing thedetection cell device 3 assembled with the semiconductor chip on adisplacement device 5, and adjusting the displacement device to enable the laser generated by thelaser device 1 to irradiate the semiconductor chip.

S2, photocurrent response test:

adjusting the Z-direction height of thedisplacement device 5 to enable the semiconductor chip on thedetection cell device 3 to be located at the position of 0.8-1.2cm of the focal point of the laser generated by thelaser device 1, namely in a non-focusing state, and turning off or on the laser.

Connecting a pH sensitive semiconductor chip with a working electrode, taking a silver/silver chloride reference electrode as a reference electrode, and taking a platinum wire as a counter electrode to form a three-electrode system; the voltage sweep range of the SWV is: 0.4 to-1.2V, the amplitude is 0.05V, and the scanning frequency is 1 KHz; the voltage sweep range of the ACV is: 0.1 to-1.5V, amplitude of 0.02V and scanning frequency of 200 Hz.

S3, pH sensitivity test:

and adjusting the Z-direction height of thedisplacement device 5 to enable the semiconductor chip on thedetection cell device 3 to be positioned at the position of a laser focus generated by thelaser device 1, namely, in a non-focusing state, and inspecting the sensitivity of the pH sensitive semiconductor chip to the pH of the solution. 2ml of different (pH value: 3-9.2) 0.1M NaCl buffer solutions were added to the detection chamber, and the I-V curves corresponding to SWV and ACV were tested accordingly. The voltage sweep range of the SWV is: 0.4 to-1.2V, the amplitude is 0.05V, and the scanning frequency is 1 KHz; the voltage sweep range of the ACV is: 0.1 to-1.5V, amplitude of 0.02V and scanning frequency of 200 Hz.

S4, impedance in-situ detection and imaging:

step 1, adjusting the Z-direction height of adisplacement device 5, focusing laser on the surface of an impedance sensitive semiconductor chip, and inspecting the impedance in-situ detection function of the optical addressing square wave/alternating current voltammetry. Specifically, a standard photolithography technique is used to prepare SU 82005 patterns on the surface of a semiconductor chip, wherein the photoresist thickness is 5 μm, and the patterns are squares with a side length of 100 μm. The position of the impedance sensitive semiconductor chip relative to the laser is adjusted through thedisplacement device 5, so that the laser just irradiates a photoresist covered area or a photoresist uncovered area, and an SWV curve and an ACV I-V curve are respectively tested. Wherein the voltage scanning range of the SWV is-0.4 to-0.8V, the amplitude is 0.05V, and the scanning frequency is 100 Hz; the ACV potential scanning range is-0.3 to-0.55V, the potential amplitude is 0.1V, and the scanning frequency is 10 Hz.

And 2, based on the SWV I-V curve result obtained in thestep 1, carrying out two-dimensional scanning on the SU8 pattern at a potential of-0.8V to obtain an SWV photo-current diagram, and comparing the SWV photo-current diagram with an optical diagram shot by an optical imaging system. The pattern is subjected to SWV test (-0.78 to-0.8V, amplitude 0.05V and scanning frequency 100Hz) by two-dimensional scanning (step length: 4 μm, dead time: 2.3s, scanning range: 200 μm × 200 μm) of the displacement device in the x and y directions, namely, the SWV current of the point under-0.8V is collected every time the displacement device moves to the point, so that a photocurrent two-dimensional image is obtained.

An SU 82005 pattern was prepared on the surface of the semiconductor chip using standard photolithography, with a photoresist thickness of 5 μm and a pattern of 100 μm square.

Step 3) detecting the resolution of the optical addressing SWV impedance imaging under-0.8V potential: through the linear movement of the displacement device in the x direction (step length: 2 μm, dead time: 2.3s), the pattern edge is subjected to SWV scanning (-0.78 to-0.8V, amplitude 0.05V and scanning frequency 100Hz), namely, when the displacement device moves to one point, the SWV current of the point under-0.8V is collected, so that a photocurrent-position (I-x) curve is obtained, the curve is subjected to differential processing, and the half-peak width is obtained, namely the spatial resolution of the optical addressing SWV impedance imaging.

For the above described applications for surface potential sensing and impedance imaging, the detection results are as follows:

when the potential scanning range is 0.4 to-1.2V, the potential amplitude is 0.05V, and the scanning frequency is 1KHz, the SWV I-V curve of the pH sensitive semiconductor chip is shown in FIG. 3, and it can be known from FIG. 3 that the photocurrent changes with the potential in an "s" curve: when the potential is more positive (0.4 to-0.1V), the SWV current is lower and has smaller change, and corresponds to the accumulation layer of the specific I-V curve of the field effect structure; along with the continuous reduction of the potential, the absolute value of the photocurrent is gradually increased, and the photocurrent corresponds to a depletion layer of the field effect structure; the current reaches saturation when the potential is minus 1.2V, and the current corresponds to an inversion layer of a field effect structure.

When the potential scanning range is 0.1 to-1.5V, the amplitude is 0.02V, and the scanning frequency is 200Hz, the ACV photocurrent curve of the pH sensitive semiconductor chip is shown in FIG. 4. As can be seen from fig. 4, the photocurrent also shows the trend of "s" curve with the potential: when the potential is more positive, the current is relatively lower and the change is smaller, and the potential is 0.1 to-0.1V; with the continuous reduction of the potential, the photocurrent gradually increases until the saturation is reached around-1.2V.

When the potential scanning range is 0.4 to-1.2V, the potential amplitude is 0.05V, and the scanning frequency is 1KHz, the optical addressing SWV curve of the pH sensitive semiconductor chip tested in the solution with different pH values is shown in FIG. 5 a; the I-V curve gradually shifts towards the negative potential direction along with the increase of the pH value of the solution; as shown in FIG. 5b, the pH sensitivity was 55.9mV/pH at a constant photocurrent of-100 nA.

When the potential scanning range is 0.3 to-0.8V, the amplitude is 0.02V, and the scanning frequency is 200Hz, the optical addressing ACV curve of the pH sensitive semiconductor chip tested in the solution with different pH values is shown in FIG. 6 a. As the pH of the solution increases, the I-V curve also gradually shifts toward a negative potential. As shown in FIG. 6b, the pH sensitivity was 46.7mV/pH at a constant photocurrent of 405 nA.

When the potential scanning range is-0.4 to-0.8V, the potential amplitude is 0.05V, and the scanning frequency is 100Hz, the SWV curve of the scanning of the focused laser on the SU8 photoresist covered area and the uncovered area on the impedance sensitive semiconductor chip is shown in FIG. 7. Since the SU8 photoresist increases the impedance of the chip surface in situ, the absolute value of the photocurrent is significantly reduced in the current saturation region, i.e., the inversion layer, where the chip surface has SU8 coverage compared to the region withoutSU 8.

When the potential scanning range is-0.3 to-0.55V, the potential amplitude is 0.1V and the scanning frequency is 10Hz, the ACV curves of the areas covered by the SU8 photoresist and the areas not covered by the SU-8 photoresist of the focused laser on the impedance-sensitive semiconductor chip are shown in FIG. 8, and the impedance of the chip surface can be increased in situ by the SU8 photoresist, so that the photocurrent of the chip surface with the SU8 covering part is remarkably reduced compared with that without the SU8 on the inversion layer.

Taking the SU8 pattern as the center, an optical image was taken using an optical imaging system as shown in fig. 9 a. Taking SU8 pattern as the center, performing xy-direction two-dimensional scanning (step length: 4 μm, dead time: 2.3s, scanning range: 200 μm × 200 μm) by a displacement device, simultaneously performing SWV test (-0.78-0.8V, amplitude 0.05V, scanning frequency 100Hz), and obtaining SWV photocurrent two-dimensional image as shown in FIG. 9b by taking the corresponding position coordinate of-0.8V and SWV current. Since SU8 photoresist increases the impedance of the chip surface in situ, the photocurrent is significantly lower in the area covered by the photoresist. The SWV photo-streaming image can better correspond to the optical image.

By means of linear movement of the displacement device in the x direction (step size: 2 μm, dead time: 2.5s, scanning range: 90 μm), optical addressing SWV scanning is performed on the edges of the pattern of the impedance sensitive semiconductor chip SU8 to-0.78V, amplitude is 0.05V, scanning frequency is 100Hz, and the SWV current magnitude under the corresponding position coordinate of-0.8V is taken to obtain a current-position I-x curve as shown in FIG. 9a, and a curve obtained by differentiating the I-x curve is shown in FIG. 9 b. As can be seen from fig. 9a, since SU8 increases the in-situ impedance of its coverage area, the absolute value of the photocurrent increases dramatically as the laser light moves from the SU8 coverage area to the SU 8-free area. The spatial resolution of the optically addressed SWV is about 5.2 μm, as can be seen by the half-width after the differentiation process.

The invention provides an addressable photoelectrochemical detection method, which uses a beam of constant laser to irradiate a semiconductor field effect structure to generate local photon-generated carriers, and simultaneously uses the SWV or ACV function of an electrochemical workstation to modulate the external voltage of a semiconductor chip to obtain photocurrent through detection. The results show that when silicon nitride is used as the sensitive layer, the detection of the pH value of the solution can be achieved. In addition, the semiconductor chip based on SAMs insulation can be used for in-situ detection and imaging of chip surface impedance. Compared with the traditional electrochemical analysis method, the light-addressable SWV/ACV provided by the invention has certain spatial resolution capability, and provides a solution for high-flux multi-site electrochemical detection.

Claims (10)

Translated fromChinese

1.一种光寻址方波/交流伏安电化学传感系统，其特征在于，包括激光装置(1)、半导体芯片(2)、检测池装置(3)、电化学检测装置(4)、位移装置(5)和光学成像装置(18)；半导体芯片(2)固定于检测池装置(3)下端，检测池装置(3)上设有通孔容腔，通孔容腔内用于放置检测液，检测液能够与半导体芯片(2)上端面接触，电化学检测装置(4)的对电极(6)和参比电极(7)间隔放置于检测液内，电化学检测装置(4)的工作电极(8)与半导体芯片(2)下端电连接，激光装置(1)和光学成像装置(18)设置于检测池装置(3)上端，光学成像装置(18)的光源和激光装置(1)的激光能够通过通孔容腔照射于半导体芯片(2)上表面，半导体芯片(2)和检测池装置(3)固定于位移装置(5)上。1. an optical addressing square wave/AC voltammetry electrochemical sensing system, is characterized in that, comprises laser device (1), semiconductor chip (2), detection cell device (3), electrochemical detection device (4) , a displacement device (5) and an optical imaging device (18); the semiconductor chip (2) is fixed on the lower end of the detection cell device (3), the detection cell device (3) is provided with a through-hole cavity, and the through-hole cavity is used for The detection solution is placed, the detection solution can be in contact with the upper end face of the semiconductor chip (2), the counter electrode (6) and the reference electrode (7) of the electrochemical detection device (4) are placed in the detection solution at intervals, and the electrochemical detection device (4) ) of the working electrode (8) is electrically connected to the lower end of the semiconductor chip (2), the laser device (1) and the optical imaging device (18) are arranged on the upper end of the detection cell device (3), the light source of the optical imaging device (18) and the laser device The laser of (1) can be irradiated on the upper surface of the semiconductor chip (2) through the through-hole cavity, and the semiconductor chip (2) and the detection cell device (3) are fixed on the displacement device (5).2.根据权利要求1所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，电化学检测装置(4)包括电化学工作站、对电极、参比电极和工作电极，对电极与、参比电极和工作电极均与电化学工作站相连，电极采用铂丝，参比电极采用Ag/AgCl参比电极，工作电极连接于半导体芯片。2. a kind of light addressing square wave/AC voltammetry electrochemical sensing system according to claim 1, is characterized in that, electrochemical detection device (4) comprises electrochemical workstation, counter electrode, reference electrode and work station The electrode, the counter electrode, the reference electrode and the working electrode are all connected with the electrochemical workstation, the electrode adopts platinum wire, the reference electrode adopts Ag/AgCl reference electrode, and the working electrode is connected to the semiconductor chip.3.根据权利要求1所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，激光装置(1)包括激光控制器(19)、激光器(20)、准直透镜(21)、分光棱镜(22)和放大物镜(23)，放大物镜(23)设置于检测池装置(3)上端，准直透镜(21)设置于激光器(20)激光发射端，分光棱镜(22)设置于准直透镜(21)和放大物镜(23)之间，激光器连接于激光控制器。3. A light addressing square wave/AC voltammetry electrochemical sensing system according to claim 1, wherein the laser device (1) comprises a laser controller (19), a laser (20), a collimator A lens (21), a beam splitting prism (22) and a magnifying objective lens (23), the magnifying objective lens (23) is arranged on the upper end of the detection cell device (3), the collimating lens (21) is arranged on the laser emission end of the laser (20), and the beam splitting prism (22) is arranged between the collimating lens (21) and the magnifying objective lens (23), and the laser is connected to the laser controller.4.根据权利要求1所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，光学成像装置包括LED照明光源(24)、场镜(25)和CCD相机，CCD相机连接有计算机(26)，计算机(26)用于获取图像并存储，场镜(25)设置于分光棱镜(22)一侧，场镜(25)、分光棱镜(22)和放大物镜(23)在一条直线上。4. A light addressing square wave/AC voltammetry electrochemical sensing system according to claim 1, wherein the optical imaging device comprises an LED illumination light source (24), a field lens (25) and a CCD camera, The CCD camera is connected with a computer (26), the computer (26) is used for acquiring and storing images, a field lens (25) is arranged on one side of the beam splitter prism (22), the field lens (25), the beam splitter prism (22) and the magnifying objective lens ( 23) in a straight line.5.根据权利要求2所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，半导体芯片(2)采用pH敏感半导体芯片或阻抗敏感半导体芯片。5 . The light addressing square wave/AC voltammetry electrochemical sensing system according to claim 2 , wherein the semiconductor chip ( 2 ) adopts a pH-sensitive semiconductor chip or an impedance-sensitive semiconductor chip. 6 .6.根据权利要求5所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，pH敏感半导体芯片包括由上至下依次堆叠的敏感层(9)、绝缘层(10)、半导体层(11)和欧姆接触层(12)，欧姆接触层(12)与电化学检测装置(4)的工作电极(8)电连接，敏感层(9)与检测池装置(3)内的电解液接触，阻抗敏感半导体芯片包括上至下依次堆叠的绝缘层(10)、半导体层(11)和欧姆接触层(12)，欧姆接触层(12)与电化学检测装置(4)的工作电极(8)电连接，绝缘层(10)与检测池装置(3)内的电解液接触。6. A light-addressable square wave/AC voltammetry electrochemical sensing system according to claim 5, wherein the pH-sensitive semiconductor chip comprises a sensitive layer (9), an insulating layer stacked in sequence from top to bottom (10), a semiconductor layer (11) and an ohmic contact layer (12), the ohmic contact layer (12) is electrically connected to the working electrode (8) of the electrochemical detection device (4), and the sensitive layer (9) is connected to the detection cell device ( 3) in contact with the electrolyte, the impedance-sensitive semiconductor chip includes an insulating layer (10), a semiconductor layer (11) and an ohmic contact layer (12) stacked in sequence from top to bottom, and the ohmic contact layer (12) is connected to an electrochemical detection device ( 4) The working electrode (8) is electrically connected, and the insulating layer (10) is in contact with the electrolyte in the detection cell device (3).7.根据权利要求1所述的一种光寻址方波/交流伏安电化学传感系统，其特征在于，检测池装置(3)包括检测腔体(13)和电连接片(14)，检测腔体(13)上设有通孔腔体，半导体芯片(2)与检测腔体(13)下端面密封接触，电连接片(14)设置于半导体芯片(2)下端，电连接片(14)与半导体芯片(2)电连接。7. A light addressing square wave/AC voltammetry electrochemical sensing system according to claim 1, wherein the detection cell device (3) comprises a detection cavity (13) and an electrical connection piece (14) The detection cavity (13) is provided with a through-hole cavity, the semiconductor chip (2) is in sealing contact with the lower end face of the detection cavity (13), and the electrical connection piece (14) is arranged on the lower end of the semiconductor chip (2). (14) is electrically connected to the semiconductor chip (2).8.一种基于权利要求5所述光寻址方波/交流伏安电化学传感系统的光寻址方波/交流伏安电化学测试方法，其特征在于，包括以下步骤：8. a light addressing square wave/AC voltammetry electrochemical test method based on the light addressing square wave/AC voltammetry electrochemical sensing system of claim 5, is characterized in that, comprises the following steps:S1、将固定有pH敏感半导体芯片的检测池装置固定于位移装置上，在检测池装置的通孔容腔内加入不同pH值的缓冲盐电解液；将电化学检测装置的对电极和参比电极放入电解液内，将工作电极与pH敏感半导体芯片的欧姆接触层相连；S1. Fix the detection cell device with the pH-sensitive semiconductor chip fixed on the displacement device, and add buffer salt electrolytes of different pH values into the through-hole cavity of the detection cell device; connect the counter electrode of the electrochemical detection device and the reference The electrode is placed in the electrolyte, and the working electrode is connected to the ohmic contact layer of the pH-sensitive semiconductor chip;S2、调节位移装置使激光器产生的激光通过检测池装置的通孔容腔照射在pH敏感半导体芯片上端，并使激光聚焦点位于半导体表面0.8-1.2cm处；S2. Adjust the displacement device so that the laser generated by the laser is irradiated on the upper end of the pH-sensitive semiconductor chip through the through-hole cavity of the detection cell device, and the laser focusing point is located at 0.8-1.2 cm of the semiconductor surface;S3、采用电化学工作站对不同pH溶液依次进行SWV和ACV电化学测试，获得暗/光电流-电位曲线，从而完成寻址方波/交流伏安电化学传感检测。S3, using an electrochemical workstation to sequentially perform SWV and ACV electrochemical tests on different pH solutions to obtain dark/photocurrent-potential curves, thereby completing addressing square wave/AC voltammetry electrochemical sensing detection.9.一种基于权利要求5所述光寻址方波/交流伏安电化学传感系统的光寻址方波/交流伏安电化学成像方法，其特征在于，包括以下步骤：9. A light addressing square wave/AC voltammetry electrochemical imaging method based on the light addressing square wave/AC voltammetry electrochemical sensing system of claim 5, characterized in that, comprising the following steps:S1、将固定有阻抗敏感半导体芯片的检测池装置固定于位移装置上，在检测池装置内加入电解液；将电化学检测装置的对电极和参比电极放入电解液内，将工作电极通过电连接片与阻抗敏感半导体芯片的欧姆接触层相连；S1, fix the detection cell device with the impedance-sensitive semiconductor chip fixed on the displacement device, add electrolyte in the detection cell device; put the counter electrode and the reference electrode of the electrochemical detection device into the electrolyte, pass the working electrode through The electrical connection piece is connected with the ohmic contact layer of the impedance-sensitive semiconductor chip;S2、调节位移装置，使激光器产生的激光通过检测池装置的通孔容腔照射在阻抗敏感半导体芯片表面，并使激光聚焦点位于半导体芯片表面；S2, adjust the displacement device, so that the laser generated by the laser is irradiated on the surface of the impedance-sensitive semiconductor chip through the through-hole cavity of the detection cell device, and the laser focusing point is located on the surface of the semiconductor chip;S3、采用电化学工作站依次进行SWV和ACV电化学测试，分别获得测试SWV和ACV的I-V曲线；S3. Use an electrochemical workstation to perform electrochemical tests of SWV and ACV in sequence, and obtain the I-V curves of the tested SWV and ACV respectively;S4、调节位移装置，通过光学成像系统进行观察，使半导体芯片以光刻图案为中心相对于激光在水平面上进行二维扫描，取对应坐标固定电位下SWV光电流大小，从而获得光刻图案的光电流分布图像，即光寻址方波伏安电化学阻抗图。S4. Adjust the displacement device and observe through the optical imaging system, so that the semiconductor chip is two-dimensionally scanned relative to the laser on the horizontal plane with the lithography pattern as the center, and the SWV photocurrent size under the fixed potential of the corresponding coordinates is obtained, so as to obtain the lithography pattern. Photocurrent distribution image, i.e., photoaddressable square wave voltammetry electrochemical impedance map.10.根据权利要求9所述光寻址方波/交流伏安电化学成像方法，其特征在于，调节位移装置，使电半导体芯片相对于激光在水平方位上线性移动，对半导体芯片上的光刻图案边缘进行SWV扫描，从而获得固定电位下电流-位置曲线，对电流-位置曲线进行微分处理，得到半峰宽大小，即为光寻址方波伏安阻抗成像的空间分辨率大小。10. The optical addressing square wave/AC voltammetry electrochemical imaging method according to claim 9, wherein the displacement device is adjusted to make the electric semiconductor chip move linearly in the horizontal azimuth relative to the laser, and the light on the semiconductor chip is adjusted. SWV scanning is performed on the edge of the engraved pattern to obtain the current-position curve at a fixed potential, and the current-position curve is differentiated to obtain the half-peak width, which is the spatial resolution of the square-wave voltammetric impedance imaging.

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