Circuitless Micro-Sensing System and Signal Detection Method

Abstract

The present disclosure provides a circuitless micro sensing system and a signal detection method. The system includes: a semiconductor photodiode for receiving excitation light and generating an optical signal; a resistor to be measured, which forms a closed loop with the semiconductor photodiode, and the photoluminescence intensity of the semiconductor photodiode is controlled by changing the resistor to be measured. The circuitless micro sensing system can simultaneously achieve three functions of optical energy harvesting, electrical signal amplification, and optical signal transmission, capture real-time biophysical and biochemical activities in an optical manner, without a complex sensing circuit, and exhibits a superlinear relationship with conductance. Using this mechanism, optical monitoring of biophysical signals and biochemical signals can be realized.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronics, and particularly to a circuitless micro sensing system and a signal detection method. Background Art

[0002] In the past decade, due to the multiple functions of bioelectronic sensors such as direct biophysical monitoring, physiological signals (electrophysiology, temperature, pressure, etc.) and biochemical signals (blood oxygen, blood glucose, ion concentration, etc.), they have been widely used in clinical practice. In order to achieve remote, non-invasive, accurate and continuous operation, various methods using microwave, light and ultrasonic signals have been developed for wireless energy harvesting and signal transmission. Conventional skin-mounted sensors or general bioelectronic sensors still require a precision circuit with multiple device components, which at least include a power supply, a signal amplifier and a data transmitter. However, the complex circuit design, additional information display and energy supply upgrade methods limit their further miniaturization, convenience and low-power expansion in physiological information sensing applications. Facing the complex and changeable environment, problems such as device function failure, interference signal transmission and shortened operation life are likely to occur. Therefore, there is an urgent need to propose a new sensing theory mechanism and design a corresponding efficient, convenient and stable device system structure. Summary of the Invention

[0003] (I) Technical Problems to be Solved

[0004] In view of the above technical problems, the main object of the present disclosure is to provide a circuitless micro sensing system for solving at least one of the above technical problems.

[0005] (II) Technical Solutions

[0006] To achieve the above object, the present disclosure provides a circuitless micro sensing system for signal detection, including:

[0007] A semiconductor photodiode for receiving excitation light and generating an optical signal;

[0008] A resistor under test, which forms a closed loop with the semiconductor photodiode, and controls the photoluminescence intensity of the semiconductor photodiode by changing the resistor under test.

[0009] Optionally, the photoluminescence intensity of the semiconductor photodiode and the resistor under test satisfy the following relationship:

[0010]

[0011] wherein, R is the resistor under test, k is the Boltzmann constant, T is the Kelvin temperature, q is the unit charge, S is the effective surface area of the device, J phThe photocurrent derived from the excitation light power density, J th The thermal radiation absorbed from the environment, η m The coupling coefficient of the microscope, η ext The external luminous efficiency, n Photons The number of emitted photons captured.

[0012] Optionally, the semiconductor photodiode includes: a substrate on which a sacrificial layer is grown, an n-type contact layer is grown on the surface of the sacrificial layer away from the substrate, a distributed Bragg reflector (DBR layer) is grown on the surface of the n-type contact layer away from the sacrificial layer, and an active layer is grown on the surface of the DBR layer away from the n-type contact layer; a p-type contact layer is grown on the surface of the active layer away from the DBR layer; wherein, ohmic electrodes are provided on the surfaces of the n-type contact layer and the p-type contact layer for electrically connecting with the resistance to be measured to form a closed loop.

[0013] Optionally, the resistance to be measured includes a skin resistance or a thermistor or a piezoresistor or a chemical reagent.

[0014] Optionally, the chemical reagent includes ascorbic acid (AA).

[0015] Optionally, the semiconductor photodiode is prepared from a III-V semiconductor material with a high external luminous efficiency.

[0016] Optionally, the semiconductor photodiode includes a thin-film micro light-emitting diode.

[0017] Another aspect of the present disclosure provides a signal detection method for a circuit-free micro sensing system, including: irradiating the semiconductor photodiode with excitation light; changing the parameter to be measured of the resistance to be measured, and measuring the photoluminescence intensity of the semiconductor photodiode and the parameter to be measured of the resistance to be measured.

[0018] Optionally, the parameter to be measured includes a resistance value or a current value or a voltage value or a temperature or a pressure or a concentration.

[0019] Optionally, the wavelength range of the excitation light is 500 - 600 nm.

[0020] (III) Beneficial effects

[0021] A circuit-free micro sensing system proposed by the present disclosure has the following beneficial effects:

[0022] The circuitless micro sensing system in the present disclosure can simultaneously achieve three functions: optical energy harvesting, electrical signal amplification, and optical signal transmission. On the one hand, based on the semiconductor photodiode's ability to simultaneously absorb and emit photons, wireless optical energy collection and optical signal transmission are realized, capturing real-time biophysical and biochemical activities optically, thus eliminating the need for complex sensing circuits; on the other hand, based on the photon recycling effect, the photoluminescence intensity of the semiconductor photodiode exhibits a superlinear relationship with conductivity. Using this mechanism, optical monitoring of transient biophysical signals including skin electrical signals, pressure, and temperature, as well as biochemical signals such as AA concentration, can be achieved. In terms of its application coverage, accuracy, and sensitivity, the circuitless micro sensing system proposed in the present disclosure is superior to traditional complex wired electrical sensing circuits. Description of the Drawings

[0023] Figure 1 Schematically shows the circuitless micro sensing system in the embodiments of the present disclosure;

[0024] Figure 2 Schematically shows the structure of the semiconductor photodiode in the embodiments of the present disclosure;

[0025] Figure 3 Schematically shows the flowchart of the signal detection method based on the circuitless micro sensing system proposed in the embodiments of the present disclosure;

[0026] Figure 4 Shows the optoelectronic sensing schematic diagram of the circuitless micro sensing system in the first embodiment of the present disclosure in a galvanic skin response (GSR) test;

[0027] Figure 5 Shows the microscopic images of the photoluminescence intensity of a human subject under basal and deep breathing conditions when measuring GSR using the circuitless micro sensing system in the first embodiment of the present disclosure;

[0028] Figure 6 Shows the comparison result between the GSR measurement result of a human subject using the circuitless micro sensing system in the first embodiment of the present disclosure and the theoretical predicted value;

[0029] Figure 7 Shows the test result of GSR using the circuitless micro sensing system in the first embodiment of the present disclosure;

[0030] Figure 8 Shows the GSR test result using a commercial GSR sensor in the first comparative example of the present disclosure;

[0031] Figure 9 Shows the optoelectronic sensing schematic diagram of the sensing system composed of a thin-film micro light-emitting diode and a thermistor in the second embodiment of the present disclosure;

[0032] Figure 10 Figure 2 shows the curve of the photoluminescence intensity of the thin-film micro light-emitting diode varying with the temperature of the thermistor in the second embodiment of the present disclosure; among them, curve a is the curve of the photoluminescence intensity varying with temperature, and curve b is the curve of the resistance value of the thermistor varying with temperature;

[0033] Figure 11 Figure 3 shows the schematic diagram of the optoelectronic sensing of the sensing system composed of the thin-film micro light-emitting diode and the varistor in the third embodiment of the present disclosure;

[0034] Figure 12 Figure 4 shows the curve of the photoluminescence intensity of the thin-film micro light-emitting diode varying with the pressure of the varistor in the third embodiment of the present disclosure; among them, curve a is the curve of the photoluminescence intensity varying with temperature, and curve b is the curve of the resistance value of the thermistor varying with temperature;

[0035] Figure 13 Figure 5 shows the schematic diagram of the optoelectronic sensing of the sensing system composed of the thin-film micro light-emitting diode and the AA solution in the fourth embodiment of the present disclosure;

[0036] Figure 14 Figure 6 shows the photoluminescence intensity response curve when 50 μL of 10 mM AA is continuously added to the phosphate buffer solution (PBS) in the fourth embodiment of the present disclosure;

[0037] Figure 15 Figure 7 shows the chronoamperometric response curve when 50 μL of 10 mM AA is continuously added to the PBS solution in the fourth embodiment of the present disclosure;

[0038] Figure 16 Figure 8 shows the results of adding PBS and AA and the result of adding pure PBS in the fourth embodiment of the present disclosure and Comparative Example 2, where curve a is the result of adding PBS and AA in the fourth embodiment, and curve b is the result of adding pure PBS in Comparative Example 2;

[0039] Figure 17 Figure 9 shows the calibration curve of the photoluminescence intensity varying with the concentration of the AA solution in the fourth embodiment of the present disclosure.

[0040] Description of reference numerals

[0041] 1 - Substrate; 2 - Sacrificial layer; 3 - n-type contact layer; 4 - DBR layer; 5 - Active layer; 6 - p-type contact layer. Detailed implementation manners

[0042] To make the purpose, technical solution, and advantages of the present disclosure clearer and more understandable, the following further details the present disclosure in combination with specific details and with reference to the accompanying drawings.

[0043] As introduced in the background art, the bioelectronic sensors in the prior art still require precise circuits with multiple device components, which at least include a power supply, a signal amplifier, and a data transmitter. However, the complex circuit design, additional information display, and energy supply upgrade methods limit their further miniaturization, convenience, and low-power expansion in physiological information sensing applications. Facing the complex and changeable environment, problems such as device function failure, interference signal transmission, and shortened operating life are likely to occur. Therefore, there is an urgent need to propose a new sensing theory mechanism and design an efficient, convenient, and stable device system structure accordingly.

[0044] To solve the above problems, the present disclosure discovers through research that a semiconductor photodiode can serve as an energy generator (through the photoelectric effect), a signal amplifier (the characteristics of the diode), and a light emitter (through the radiative recombination of carriers). In addition, for a diode with high electron-photon and photon-electron conversion efficiencies, its photon recycling effect can be controlled by changing electrical signals such as voltage, current, and resistance, thereby utilizing its photoluminescence intensity. In other words, this means that such a mechanism can provide a method for detecting biological and biochemical signals. Based on this, the present disclosure proposes a circuitless micro sensing system.

[0045] Figure 1 Schematically shows a circuitless micro sensing system proposed in an embodiment of the present disclosure. As Figure 1 shown, the circuitless micro sensing system includes: a semiconductor photodiode, which is used to receive the excitation light and generate an optical signal; a resistance to be measured, which forms a closed loop with the semiconductor photodiode, and controls the photoluminescence intensity of the semiconductor photodiode by changing the resistance to be measured.

[0046] The semiconductor photodiode in the circuitless micro sensing system can be used as an energy absorber, a signal amplifier, and a light emitter at the same time. Based on the photon recycling effect related to conductance, the photoluminescence intensity of the semiconductor photodiode can be controlled by changing the resistance to be measured, thereby realizing the detection of the signal of the resistance to be measured.

[0047] Compared with traditional bioelectric sensors, the circuitless micro sensing system proposed in the embodiment of the present disclosure captures real-time biophysical and biochemical activities optically, thus eliminating the need for complex sensing circuits. Moreover, based on the photon recycling effect, the photoluminescence intensity of the semiconductor photodiode exhibits a superlinear relationship with the external conductance, and this mechanism can be used to monitor biophysical signals and biochemical signals, with a wider range of applications.

[0048] In the embodiment of the present disclosure, the photoluminescence intensity of the semiconductor photodiode and the resistance to be measured satisfy the following relationship:

[0049]

[0050] Wherein, R is the resistance to be measured, k is the Boltzmann constant, T is the Kelvin temperature, q is the unit charge, S is the effective surface area of the device, J ph is the photocurrent derived from the excitation light power density, J th is the thermal radiation absorbed from the environment, η m is the coupling coefficient of the microscope, η ext is the external luminous efficiency, n Photons is the number of emitted photons captured.

[0051] Based on the above formula, due to the characteristics of the diode, the photoluminescence intensity has an exponential relationship with the resistance value, and the photoluminescence intensity increases with the resistance. Therefore, the photoluminescence intensity can be controlled by adjusting the resistance, which provides an effective amplification mechanism for bioelectronic sensing.

[0052] Figure 2 Schematically shows a semiconductor photodiode structure proposed in an embodiment of the present disclosure.

[0053] As Figure 2 shown, in the embodiment of the present disclosure, the semiconductor photodiode includes: a substrate 1, on which a sacrificial layer 2 is grown, an n-type contact layer 3 is grown on the surface of the sacrificial layer 2 away from the substrate 1, a DBR layer 4 is grown on the surface of the n-type contact layer 3 away from the sacrificial layer 2, and an active layer 5 is grown on the surface of the DBR layer 4 away from the n-type contact layer 3; a p-type contact layer 6 is grown on the surface of the active layer 5 away from the DBR layer 4; wherein, ohmic electrodes are provided on the surfaces of the n-type contact layer 3 and the p-type contact layer 6 for forming a closed loop with the resistance to be measured.

[0054] In an embodiment of the present disclosure, the semiconductor photodiode is prepared from III-V semiconductor materials with high external luminous efficiency. For example, the material of the substrate 1 of the semiconductor photodiode includes GaAs, the material of the sacrificial layer 2 includes Al 0.95 Ga 0.05 As, the material of the n-type contact layer 3 includes GaAs, and a certain amount of Si element can also be doped, the material of the p-type contact layer 6 includes GaP, and a certain amount of C element can be doped, the material of the DBR layer 4 includes In 0.5 Al 0.5 P / In 0.5 Al 0.25 Ga 0.25P, a certain amount of Si element can be doped, and the material of the active layer 5 includes InGaP / InAlP. If the semiconductor photodiode is made of III-V semiconductor materials with high external luminous efficiency, it will produce strong photoluminescence, so when the micro-sensing system is used to monitor biophysical signals and biochemical signals, its detection sensitivity will be higher. In one embodiment of the present disclosure, the semiconductor photodiode can be a thin-film micro-light-emitting diode. The reduction in device size is conducive to integration with flexible substrates and biological tissues, and is also conducive to enhancing the response speed of the device and achieving more accurate spatiotemporal positioning and optical detection.

[0055] Based on the above circuit-free micro-sensing system, the present disclosure also proposes a signal detection method based on a circuit-free micro-sensing system, such as Figure 3 As shown, the detection method includes: irradiating a semiconductor photodiode with excitation light; changing a parameter to be measured of the resistor to be measured, and measuring the photoluminescence intensity of the semiconductor photodiode and the parameter to be measured of the resistor to be measured.

[0056] According to the embodiment of the present disclosure, the wavelength range of the excitation light is 500-600 nm. Specifically, the wavelength of the excitation light can be selected according to the photoluminescence performance of the semiconductor photodiode and the test purpose.

[0057] According to the embodiments of the present disclosure, in specific applications, the resistor to be measured and the required test parameters can be selected according to the actual test needs and the test environment. For example, when detecting GSR, the resistor to be measured may be the skin resistance, and the parameter to be measured may be the resistance value or the current value or the voltage value. When used to detect changes in temperature or pressure signals, the resistor to be measured may be a thermistor or a varistor, and the parameter to be measured may be the temperature or the pressure or the resistance value. When used for chemical detection and analysis, the resistor to be measured may be a chemical reagent, and the parameter to be measured may be the concentration of the chemical reagent to be measured or other required indicators to be measured. For example, in the embodiments of the present disclosure, the chemical reagent may be AA. It is understandable that in the embodiments of the present disclosure, the application of the circuit-free micro-sensing system of the present disclosure in electrochemical detection is described by taking AA as an example, which is only to help those skilled in the art understand the technical content of the present disclosure, and does not limit the specific application scope of the present disclosure in chemical detection.

[0058] The following will be combined with specific embodiments to describe in detail the application of the circuit-free micro-sensing system in the present disclosure in detecting biological and biochemical signals, and connect the semiconductor photodiode to different load resistors to evaluate its electrical signal sensing ability. It should be noted that the above description of the application and Figures 4 to 17 The examples shown are merely scenarios in which the embodiments of the present disclosure can be applied, to help those skilled in the art understand the technical content of the present disclosure, but do not mean that the embodiments of the present disclosure cannot be used in other detection environments or scenarios.

[0059] Example

[0060] The thin-film micro light-emitting diode adopts the structure as Figure 2 shown, with a lateral size of 200×150μm 2 , a thickness of 5.6μm, and is made by epitaxial growth, photolithography etching, metal deposition, removing the sacrificial layer, and transfer printing. Specifically, the thin-film micro light-emitting diode includes a GaAs layer as the substrate, an Al 0.95 Ga 0.05 As layer with a thickness of 500nm, an n-type contact layer of GaAs layer with a thickness of 1000nm, a p-type contact layer of GaP layer with a thickness of 200nm, a DBR layer of In 0.5 Al 0.5 P / In 0.5 Al 0.25 Ga 0.25 P layer with a thickness of 1200nm, and an active layer of InGaP / InAlP layer with a thickness of 200nm.

[0061] In the following examples, a green light source (wavelength 545nm) is selected to irradiate the thin-film micro light-emitting diode, and its red light emission can be captured by a 560nm long-pass filter.

[0062] Example 1

[0063] In this example, the thin-film micro light-emitting diode is connected to the human skin resistance to test its signal sensing ability.

[0064] Figure 4 Fig. shows the photoelectric induction schematic diagram of the circuit-free micro sensing system of the present disclosure in the GSR test. As Figure 4 shown, two independent hydrogel Ag / AgCl electrode sheets are attached to the finger and connected to the thin-film micro light-emitting diode photoluminescence sensing system. The green light with a wavelength of 545nm is used as the excitation light to irradiate the thin-film micro light-emitting diode to produce a red photoluminescence phenomenon, which is captured by an Andor zyla 4.2Plus CMOS camera after passing through a 560nm band-pass filter. The photoluminescence intensity is measured by the CMOS camera. The laser light intensity used in the experiment is 1.91mW / mm 2 .

[0065] Comparative Example 1

[0066] The difference between Comparative Example 1 and Example 1 is that: two independent hydrogel Ag / AgCl electrode sheets are connected to a commercial GSR circuit module (DLCK365, Techtronic), and the resistance value is measured through the commercial GSR circuit module during the experiment.

[0067] Figure 5 Shows microscopic images of the photoluminescence intensity of a human subject under basal and deep breathing conditions when measuring GSR using the circuitless micro sensing system of the present disclosure. As Figure 5 shown, when performing phased activities (such as deep breathing movements), skin resistance decreases due to stimulation, and the photoluminescence intensity decreases compared to the basal state. Thus, it can be seen that the circuitless micro sensing system in the present disclosure can well monitor the changes in electrical signals of human skin.

[0068] Furthermore, Figure 6 shows the comparison results between the GSR measurement results of a human subject using the circuitless micro sensing system of the present disclosure and the theoretical predicted values. As Figure 6 shown, the measurement results show excellent quantitative consistency with the theoretical predicted values, and the coefficient of determination (correlation) is 98.82%. In addition, the normalized change in the photon signal (I / I 0 ) is approximately 4 times that of the electrically measured GSR, demonstrating the inherent amplification ability related to the photon recycling mechanism in the diode.

[0069] Even further, Figure 7 and Figure 8 respectively show the GSR test results of using the circuitless micro sensing system of the present disclosure and a commercial GSR sensor. As Figure 7 and Figure 8 shown, the GSR results tested using the circuitless micro sensing system of the present disclosure are basically consistent with the test results of the commercial GSR circuit module, and its performance can be comparable to that of the commercial GSR induction circuit module.

[0070] Example Two

[0071] In this example, a thin film micro light emitting diode is connected to a thermistor to test its ability to sense temperature signals.

[0072] Figure 9 Shows the optoelectronic sensing schematic diagram of the sensing system composed of the thin film micro light emitting diode and the thermistor of the present disclosure. As Figure 9 shown, the thin film micro light emitting diode and the thermistor (MF55 104F3950) are connected in series using a wire, and green light with a wavelength of 545 nm is used as the excitation light to irradiate the thin film micro light emitting diode. The temperature of the thermistor is changed, and at the same time, the photoluminescence intensity of the thin film micro light emitting diode and the resistance value of the thermistor are measured.

[0073] Figure 10 Shows the curve of the photoluminescence intensity of the thin film micro light emitting diode changing with the temperature of the thermistor. As Figure 10 shown, the resistance of the thermistor decreases as the temperature increases (as Figure 10As shown by curve b in the figure, when it is connected to a photoexcited thin-film micro light-emitting diode, the temperature-dependent resistance change is optically represented as a change in the photoluminescence intensity of the thin-film micro light-emitting diode. As the temperature increases, its photoluminescence intensity decreases (as shown by curve a in the figure), and the experimental results are in good agreement with the theoretical model. Thus, based on this optoelectronic detection mechanism, the circuitless micro sensing system in the present disclosure can play its role in temperature signal sensing scenarios. Figure 10 As shown by curve a in the figure, and the experimental results are all in good agreement with the theoretical model. Thus, based on this optoelectronic detection mechanism, the circuitless micro sensing system in the present disclosure can play its role in temperature signal sensing scenarios.

[0074] Example 3

[0075] In this example, a thin-film micro light-emitting diode is connected to a piezoresistor to test its ability to sense pressure signals.

[0076] Figure 11 Schematically shows the optoelectronic sensing schematic diagram of the sensing system composed of the thin-film micro light-emitting diode and the piezoresistor (IMS003-C10A) of the present disclosure. As Figure 11 shown, the thin-film micro light-emitting diode and the piezoresistor are connected in series using wires, and green light with a wavelength of 545 nm is used as the excitation light to irradiate the thin-film micro light-emitting diode. During the experiment, different pressures are applied to the piezoresistor, and at the same time, the photoluminescence intensity of the thin-film micro light-emitting diode and the resistance value of the piezoresistor are measured.

[0077] Figure 12 Shows the curve of the photoluminescence intensity of the thin-film micro light-emitting diode changing with the pressure of the piezoresistor. As Figure 12 shown, the resistance of the piezoresistor decreases as the pressure increases (as shown by curve b in the figure), when it is connected to a photoexcited thin-film micro light-emitting diode, the pressure-dependent resistance change is optically represented as a change in the photoluminescence intensity of the thin-film micro light-emitting diode. As the pressure increases, its photoluminescence intensity decreases (as shown by curve a in the figure), and the experimental results are all in good agreement with the theoretical model. Thus, based on this optoelectronic detection mechanism, the circuitless micro sensing system in the present disclosure can achieve optoelectronic sensing of pressure. Figure 12 As shown by curve b in the figure, when it is connected to a photoexcited thin-film micro light-emitting diode, the pressure-dependent resistance change is optically represented as a change in the photoluminescence intensity of the thin-film micro light-emitting diode. As the pressure increases, its photoluminescence intensity decreases (as shown by curve a in the figure), and the experimental results are all in good agreement with the theoretical model. Thus, based on this optoelectronic detection mechanism, the circuitless micro sensing system in the present disclosure can achieve optoelectronic sensing of pressure. Figure 12 As shown by curve a in the figure), and the experimental results are all in good agreement with the theoretical model. Thus, based on this optoelectronic detection mechanism, the circuitless micro sensing system in the present disclosure can achieve optoelectronic sensing of pressure.

[0078] Example 4

[0079] In this example, the circuitless micro sensing system of the present disclosure is used to test its ability to sense chemical signals.

[0080] Figure 13 Shows the optoelectronic sensing schematic diagram of the sensing system composed of the thin-film micro light-emitting diode and the AA solution of the present disclosure. As Figure 13As shown, the positive and negative electrodes of the thin-film micro light-emitting diode are respectively connected to platinum electrodes (diameter 0.3 mm), and then the platinum electrodes are immersed in 50 mL of PBS solution (0.01 M, pH = 5), with the immersion depth of 2 cm. Green light with a wavelength of 545 nm is used as the excitation light to irradiate the thin-film micro light-emitting diode. Subsequently, every 100 s, 50 μL of 10 mM AA solution is dropped into the solution using a pipette. At the same time, a magnetic stirrer is used to stir the solution at a speed of 200 rpm / min to ensure the uniform distribution of the AA concentration. Meanwhile, the photoluminescence intensity of the thin-film micro light-emitting diode and the current in the circuit are measured. The excitation light power used in the experiment is 1.29 mW / mm 2 .

[0081] Comparative Example 2

[0082] The difference from Example 4 is that: a pure PBS solution (0.01 M, pH = 5) is used as a control instead of the AA solution.

[0083] As Figure 13 shown, the two ends of the thin-film micro light-emitting diode are connected to platinum electrodes, and the platinum electrodes are immersed in PBS (0.01 M, pH = 5). Under light illumination, the anode of the thin-film micro light-emitting diode provides a forward bias voltage, oxidizing AA to dehydroascorbic acid (DHA), consuming the current in the circuit and reducing the photo-generated carriers. These carriers can recombine within the thin-film micro light-emitting diode, and subsequently the photoluminescence intensity decreases.

[0084] Figures 14 to 17 shows the test results of the chemical signal sensing ability of the micro sensing system without a circuit of the present disclosure.

[0085] Figure 14 shows the photoluminescence intensity response curve when 50 μL of 10 mM AA is continuously added to the PBS solution in this example. As the concentration of AA increases, the dynamic response of the photoluminescence intensity of the thin-film micro light-emitting diode can be captured and presents the results as Figure 14 shown. Figure 15 shows the chronoamperometric response curve when 50 μL of 10 mM AA is continuously added to the PBS solution. As Figure 15 shown, when compared with the current measured simultaneously in the circuit, it can be clearly seen that the increased electrochemistry reaction current leads to a decrease in the photoluminescence intensity. Figure 16 Further compares the results of adding PBS and AA ( Figure 16 curve a in) with the results of adding pure PBS as a control ( Figure 16 curve b in). As Figure 16 shown, when AA is added, the photoluminescence intensity decreases significantly (as Figure 16As shown by curve a in the figure, it is confirmed that the current change is directly related to the electrochemical reaction.

[0086] Figure 17 The calibration curve of the photoluminescence intensity varying with the concentration of AA solution is shown. As Figure 17 shown, in the range of 0 - 170 μM, the photoluminescence intensity of the thin-film micro light-emitting diode has a linear relationship with the AA concentration, and the detection sensitivity is 16 photons / μM. The above results clearly demonstrate the optoelectrochemical sensing ability of the circuit-free micro sensing system in the present disclosure.

[0087] In summary, a circuit-free micro sensing system and a signal detection method proposed in the present disclosure can simultaneously achieve three functions of optical energy harvesting, electrical signal amplification, and optical signal transmission based on a semiconductor photodiode, capture real-time biophysical and biochemical activities in an optical manner, and thus do not require a complex sensing circuit. Based on the photon recycling effect, the photoluminescence intensity of the semiconductor photodiode shows a superlinear relationship with the external conductance. Using this mechanism, optical monitoring of instantaneous biophysical signals including skin electrical signals, pressure, and temperature, as well as biochemical signals such as AA concentration, can be realized. In terms of its application coverage, accuracy, and sensitivity, the circuit-free micro sensing system proposed in the present disclosure is superior to the traditional complex wired electrical sensing circuit. It can be expected that in future research, based on this optoelectronic mechanism, micron-scale and nanoscale LEDs with functionalized modified electrodes can be designed to achieve high-resolution and high-selectivity wireless and remote biochemical detection.

[0088] The above embodiments are only used to describe the preferred embodiments of the present disclosure, and do not limit the scope of the present disclosure. Without departing from the design spirit of the present disclosure, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present disclosure shall fall within the protection scope determined by the claims of the present disclosure.

Claims

1. A micro sensing system without a circuit, characterized in that, for signal detection, including: A semiconductor photodiode for receiving excitation light and generating an optical signal; A resistor to be measured, which forms a closed loop with the semiconductor photodiode, and controls the photoluminescence intensity of the semiconductor photodiode by changing the resistor to be measured; Wherein, the photoluminescence intensity of the semiconductor photodiode and the resistor to be measured satisfy the following relationship: Among them, R is the resistance to be measured, k is the Boltzmann constant, T is the Kelvin temperature, q is the unit charge, S is the effective surface area of the device, J ph is the photocurrent derived from the excitation light power density, J th is the thermal radiation absorbed from the environment, η m is the coupling coefficient of the microscope, η ext is the external luminous efficiency, n Photons is the number of emitted photons captured.

2. The system according to claim 1, characterized in that, The semiconductor photodiode includes: A substrate on which a sacrificial layer is grown, an n-type contact layer is grown on the surface of the sacrificial layer away from the substrate, a distributed Bragg reflector is grown on the surface of the n-type contact layer away from the sacrificial layer, and an active layer is grown on the surface of the distributed Bragg reflector away from the n-type contact layer; A p-type contact layer is grown on the surface of the active layer away from the distributed Bragg reflector; wherein, ohmic electrodes are provided on the surfaces of the n-type contact layer and the p-type contact layer for electrically connecting with the resistor to be measured to form a closed loop.

3. The system according to claim 1, characterized in that, The resistor to be measured includes a skin resistor or a thermistor or a piezoresistor or a chemical reagent.

4. The system according to claim 3, characterized in that, The chemical reagent includes ascorbic acid.

5. The system according to claim 1 or 2, characterized in that, The semiconductor photodiode is prepared from III–V semiconductor materials with high external luminous efficiency.

6. The system according to claim 1 or 2, characterized in that, The semiconductor photodiode includes a thin film micro light emitting diode.

7. A signal detection method using the micro sensing system based on a circuitless according to any one of claims 1-6, characterized in that, including: Irradiating the semiconductor photodiode with excitation light; Changing the parameter to be measured of the resistor to be measured, and measuring the photoluminescence intensity of the semiconductor photodiode and the parameter to be measured of the resistor to be measured.

8. The method according to claim 7, characterized in that, The parameter to be measured includes a resistance value or a current value or a voltage value or a temperature or a pressure or a concentration.

9. The method according to claim 7, characterized in that, The wavelength range of the excitation light is 500~600nm.

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