Temperature and salinity sensing device and method based on red-blue dual quantum well Micro-LED

Abstract

This invention discloses a temperature and salinity sensing device based on a red-blue dual-quantum-well Micro-LED, comprising a composite sensor, a driving control module, an electrical detection module, and a signal processing module. The composite sensor includes a light-emitting unit and a detection unit spaced apart on a sapphire substrate. They have the same GaN-based red-blue dual-quantum-well Micro-LED epitaxial structure and are coupled through the sapphire substrate. The driving control module generates a photocurrent signal and a temperature-sensitive electrical signal by switching the operating state of the detection unit. The salinity and temperature information of the liquid to be measured are acquired and processed by the electrical detection module and the signal processing module. This invention also discloses a temperature and salinity detection method based on the above device. This invention eliminates the need for complex substrate stripping and heterogeneous bonding processes, overcomes the physical limitation of low single-wavelength self-absorption rate, and achieves highly sensitive synchronous detection of temperature and salinity while possessing advantages such as compact structure, high mass production yield, and significantly improved responsivity.

Description

Technical Field

[0001] This invention belongs to the technical field of optical sensing and semiconductor optoelectronic devices, specifically relating to a temperature and salinity sensing device and a temperature and salinity detection method based on a red-blue dual quantum well Micro-LED. Background Technology

[0002] Temperature and salinity are two key physical parameters characterizing the state of a liquid environment, and they are of great significance in fields such as marine environmental monitoring, salinity gradient energy utilization, aquaculture, biomedical analysis, and microfluidic systems. Traditional temperature measurements often rely on thermistors, thermocouples, or integrated temperature sensing chips, while salinity measurements are usually based on principles such as changes in conductivity, capacitance, or refractive index. These sensing methods often require different types of sensing units, resulting in complex system structures that are difficult to miniaturize and achieve single-point synchronous measurement.

[0003] In recent years, some studies have attempted to integrate light-emitting devices and photodetectors onto the same platform to achieve salinity detection through the interaction of light and salt solutions, with the aim of achieving coordinated sensing of temperature and salinity parameters. However, existing integration schemes face bottlenecks in achieving high-sensitivity light detection: if a homogeneous material system is used to achieve both light emission and detection functions, the absorption efficiency of the emitted photons at the detector end is extremely low due to the inherent characteristics of the material's band structure, resulting in a weak photoelectric response signal that is difficult to detect minute concentration changes; if a heterogeneous material system is introduced to improve detection sensitivity, it requires complex processes such as multi-step epitaxial growth, substrate peeling, mass transfer, or heterobonding, which not only results in lengthy manufacturing processes and low yields but also makes it difficult to achieve precise alignment and stable packaging between devices at the microscale, severely restricting its practical application in miniaturized, high-reliability sensing systems.

[0004] Therefore, there is an urgent need for a homogeneous monolithic integration solution that can avoid complex substrate transfer processes while ensuring high responsiveness. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a synchronous optical sensing device and method for temperature and salinity detection based on a red-blue dual-quantum-well Micro-LED. By integrating a red quantum well and a blue quantum well on the same chip platform, the difference in the propagation characteristics of different wavelengths of light in salt solutions is utilized to enhance the optical response to salinity. Simultaneously, by combining the characteristics of the device's electrical parameters changing with temperature, synchronous detection and effective decoupling of temperature and salinity are achieved.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A temperature and salinity sensing device based on red-blue dual quantum well Micro-LEDs includes a composite sensor, a drive control module, an electrical detection module, and a signal processing module.

[0008] The composite sensor includes a light-emitting unit and a detection unit spaced apart on the front side of a sapphire substrate; the light-emitting unit and the detection unit have the same GaN-based Micro-LED epitaxial structure, including an n-type layer, a blue quantum well region, a red quantum well region and a p-type layer arranged sequentially in the vertical direction; the back side of the sapphire substrate is in contact with the liquid to be tested and forms an optical coupling transmission path between the light-emitting unit and the detection unit.

[0009] The drive control module is used to drive the light-emitting unit and switch the working state of the detection unit. The detection unit is used to generate a photocurrent signal in the zero bias or reverse bias state and to generate a temperature-sensitive electrical signal in the forward bias state.

[0010] The electrical detection module is used to acquire the photocurrent signal and the temperature-sensitive electrical signal; the signal processing module determines the salinity information of the liquid to be tested based on the photocurrent signal and determines the temperature information based on the temperature-sensitive electrical signal.

[0011] The blue quantum well region refers to a quantum well structure that can emit blue light in the emission state, and the red quantum well region refers to a quantum well structure that can emit red light in the emission state. The material is, for example, InGaN / GaN multiple quantum wells. The emission wavelength is determined by controlling the indium (In) content in the InGaN potential well layer and the thickness of the well layer (i.e., the red quantum well region has a higher indium content than the blue quantum well region).

[0012] Optionally, the drive control module includes a first constant current drive source, a switching unit, and a second constant current drive source; the first constant current drive source is used to drive the light-emitting unit to emit light signals; the switching unit is used to switch the bias state of the detection unit, wherein the detection unit is driven by the second constant current drive source in the positive bias state.

[0013] Optionally, the switching unit presets high-speed switching timing logic, causing the detection unit to alternately switch between a first time slot in the zero-bias or reverse-bias state and a second time slot in the positive-bias state.

[0014] Optionally, the switching frequency between the first time slot and the second time slot is 10 Hz to 1 kHz.

[0015] Optionally, the thickness of the well layer in the red quantum well region is greater than the thickness of the well layer in the blue quantum well region.

[0016] Optionally, the thickness of the well layer in the red quantum well region is 3-5 nm, and the thickness of the well layer in the blue quantum well region is 2-3 nm.

[0017] In the red-blue dual quantum well structure, the red quantum well has a higher indium content, which easily induces the quantum confinement Stark effect (QCSE). This invention achieves synergistic optimization of transmit and receive performance by asymmetrically finely controlling the well layer thickness of the red and blue quantum wells (i.e., the well layer thickness of the red quantum well is greater than that of the blue quantum well). On one hand, the detector end adopts a red wide-well structure, which not only effectively increases the absorption volume and capture rate of incident blue photons, but also relatively reduces the barrier binding of high-energy photogenerated carriers, enabling photogenerated electrons and holes to obtain a higher probability of escaping across the barrier under low bias. On the other hand, the light-emitting end adopts a blue narrow-well structure, which enhances the quantum localization effect and improves the modulation response speed of the light-emitting end. This targeted optimization based on well layer thickness avoids the mutual compromise between the light emission and absorption processes, thereby pushing the photoelectric responsivity of the receiver PD and the overall performance of the sensing device to a higher level. Optionally, the signal processing module has a built-in linear decoupling matrix to compensate and correct the photogenerated current signal using the temperature information.

[0018] Optionally, the method for fabricating the composite sensor includes:

[0019] A GaN-based Micro-LED epitaxial structure comprising an n-type layer, a blue quantum well region, a red quantum well region, and a p-type layer in sequence is formed on the sapphire substrate by a single epitaxial process.

[0020] Etching the GaN-based Micro-LED epitaxial structure to form the spaced light-emitting unit and detector unit;

[0021] Extraction electrodes are fabricated on the light-emitting unit and the detection unit, respectively.

[0022] A temperature and salinity detection method employs the aforementioned temperature and salinity sensing device based on a red-blue dual quantum well Micro-LED, wherein the temperature and salinity detection method includes, within one detection cycle:

[0023] The detection unit is set to a zero-bias or reverse-bias state, and the light-emitting unit is driven to emit light signals. The light signals are reflected to the detection unit through the interface between the sapphire substrate and the liquid to be tested. The photocurrent signal generated by the detection unit is collected, and the salinity information of the liquid to be tested is determined through the photocurrent signal.

[0024] The detection unit is switched to a forward bias state and a forward bias constant current is applied. The temperature information is determined by using the forward voltage signal of the detection unit.

[0025] Optionally, the back side of the sapphire substrate is bonded to a microfluidic channel, which forms a continuous flow channel for the liquid to be tested.

[0026] The beneficial effects of this invention are as follows:

[0027] (1) Overcoming the bottleneck of single-wavelength self-absorption and significantly improving the sensor responsivity. By introducing red and blue dual quantum wells into the homogeneous epitaxial structure, the detector unit (PD) at the receiving end can efficiently absorb the high-energy blue light emitted from the emitting end by utilizing the red light quantum well with a narrower band gap. This breaks the physical limitation of low single-wavelength self-absorption rate and amplifies the photogenerated carrier signal without increasing the manufacturing process steps, thus significantly improving the sensitivity and signal-to-noise ratio of salinity detection.

[0028] (2) Single-stage epitaxy without transfer significantly reduces cost and process complexity. By unifying the light-emitting and detection units, the red and blue dual quantum wells can be fabricated on the same sapphire substrate through a single epitaxial growth, eliminating the complex substrate transfer process, greatly saving fabrication time and capital costs, and improving the mass production yield of the chip.

[0029] (3) Balancing high sensitivity and long-term stability. By introducing the red-blue dual quantum well structure, we can achieve high-sensitivity detection by utilizing the high sensitivity of blue light to changes in salinity in salt solutions, and improve the measurement stability of the system under long-term continuous operation by utilizing the low scattering loss and good stability of red light. Thus, we can balance the two performance requirements of sensitivity and stability that are usually difficult to meet at the same time.

[0030] (4) It is conducive to device miniaturization and system integration applications. Based on a monolithic epitaxial platform, the temperature and salinity sensing function is realized. The overall structure is compact, small in size and low in power consumption. It is easy to integrate with microfluidic chips, on-chip optical paths or packaged modules. It is suitable for application scenarios with high requirements for size and integration, such as marine in-situ monitoring, wearable sensing, and portable detection equipment. It has good engineering application prospects.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0032] Figure 1 The structural framework diagram of the temperature and salinity sensing device based on red and blue dual quantum well Micro-LED is shown in the embodiment.

[0033] Figure 2 This is a schematic diagram of the epitaxial structure of the red-blue dual quantum well Micro-LED in an embodiment.

[0034] Figure 3 The schematic diagram of the temperature and salinity sensing device based on red and blue dual quantum well Micro-LED for salinity detection is shown in the embodiment.

[0035] Figure 4The schematic diagram of the temperature and salinity sensing device based on red and blue dual quantum well Micro-LED for temperature detection is shown in the embodiment.

[0036] Figure 5 This is a schematic diagram of a temperature and salinity sensing device based on red and blue dual quantum well Micro-LED integrated into a microfluidic system, as an example. Detailed Implementation

[0037] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. The accompanying drawings are merely illustrative to facilitate a better understanding of the invention, and their specific proportions can be adjusted according to design requirements. The "upper" and "lower" relationships of relative elements and the definitions of "front" and "back" in the graphics described herein should be understood by those skilled in the art to refer to the relative positions of the components; therefore, they can all be flipped to present the same component, and all of this should fall within the scope disclosed in this specification.

[0038] like Figure 1 As shown, the embodiment of the temperature and salinity sensing device based on red-blue dual quantum well Micro-LED includes a composite sensor, a driving control module, an electrical detection module, and a signal processing module. The composite sensor includes a light-emitting unit A and a detection unit B (PD) spaced apart on the front side of a sapphire substrate 1. Light-emitting unit A and detection unit B have the same GaN-based Micro-LED epitaxial structure. The back side of the sapphire substrate 1 contacts the liquid to be tested 2, forming an optical coupling transmission path between light-emitting unit A and detection unit B. The driving control module drives the light-emitting unit and switches the operating state of the detection unit. The detection unit generates a photocurrent signal in a zero-bias or reverse-bias state and generates a temperature-sensitive electrical signal in a forward-biased state. The electrical detection module acquires the photocurrent signal and the temperature-sensitive electrical signal. The signal processing module determines the salinity information of the liquid to be tested based on the photocurrent signal and the temperature information based on the temperature-sensitive electrical signal.

[0039] The drive control module includes a first constant current drive source, a switching unit, and a second constant current drive source. The first constant current drive source is used to drive the light-emitting unit A to emit light signals; the switching unit is used to switch the bias state of the detection unit, wherein the detection unit is driven by the second constant current drive source in the forward bias state.

[0040] In this embodiment, the GaN-based Micro-LED epitaxial structure used is as follows: Figure 2As shown, the structure includes a GaN nucleation layer, a u-GaN layer, an n-GaN layer, a blue quantum well region, a red quantum well region, a p-AlGaN electron blocking layer, and a p-GaN layer sequentially formed on a sapphire substrate through a single epitaxial process. Etching is used to form epitaxial regions for spaced-out light-emitting and detection units. Mesa etching is performed on the epitaxial regions of the light-emitting and detection units, and an n-type electrode is fabricated on the n-GaN layer. An ITO layer is formed on the p-GaN layer, and a p-type electrode is fabricated thereon. The surfaces of the epitaxial structures for the light-emitting and detection units are covered with a SiO2 passivation layer. One side of the sapphire substrate is used as both the light emitting and incident surfaces.

[0041] Under the influence of an applied positive driving current, the light-emitting unit generates blue light through radiation from the blue quantum trap, which is used as the incident light source for salinity detection. For example... Figure 3 As shown, for salinity detection, the detection unit is set to a zero-bias or reverse-bias state. The light-emitting unit A generates stable light output under the drive of the first constant current source. The light propagates in the sapphire substrate 1 and undergoes total internal reflection at the interface between the sapphire substrate and the liquid to be tested (salt solution), forming an optical path from the light-emitting unit A to the detection unit B. When the salinity of the liquid changes, its refractive index changes accordingly, thereby altering the total internal reflection conditions at the interface. This causes a change in the light intensity coupled to the detection unit B, ultimately resulting in a change in the photocurrent output by the detection unit B. The photocurrent signal is acquired by the photocurrent acquisition circuit of the electrical detection module. By processing the data in the signal processing module and combining it with the pre-established calibration relationship between the photocurrent and salinity, the salinity parameter information of the salt solution to be tested can be obtained.

[0042] Different wavelengths of light exhibit varying scattering and absorption characteristics in salt solutions. Blue light is more sensitive to changes in salinity, while red light demonstrates higher propagation stability. When only a single blue quantum well structure is used, the high energy of blue photons, coupled with the limited absorption capacity of the GaN blue quantum well within its own emission band, results in low absorption efficiency of the detector unit B for incident blue light. Consequently, the photogenerated response signal is weak, leading to a low signal-to-noise ratio. The aforementioned red-blue dual quantum well structure, where the bandgap energy of the red quantum well is lower than that of the blue photon, not only effectively absorbs incident blue light, but also enhances its responsivity based on the following mechanisms: First, the incident high-energy blue photons greatly excite the photogenerated carriers in the red quantum well, causing them to transition to higher energy levels, thus making it easier for them to escape over the quantum barrier and form a photocurrent; Second, in terms of structural design, since the effective mass of photogenerated holes is much greater than that of electrons, their escape efficiency is the key to determining the performance of the photodiode. By placing the red quantum well closer to the p-GaN layer, the escape path of photogenerated holes is significantly shortened, thereby effectively reducing the recombination probability of carriers.

[0043] Furthermore, by adjusting the well layer thickness of the red quantum well, while ensuring strong absorption of high-energy blue light, the recombination probability of charge carriers in the quantum well is reduced, thereby improving the escape efficiency of photogenerated charge carriers. Preferably, the well layer thickness of the red quantum well region is set to be greater than that of the blue quantum well region to enhance its light absorption cross-section. Simultaneously, by thinning the well layer thickness of the blue quantum well, the carrier recombination lifetime can be reduced, thereby increasing the modulation bandwidth at the emitting end and reducing the crosstalk effect caused by excess charge carriers diffusing into the absorption region. Specifically, the blue and red quantum wells employ an asymmetric design in terms of thickness (well width). The blue quantum well employs a narrow-well structure of 2-3 nm to enhance the quantum localization effect and shorten the radiative recombination lifetime, ensuring that the emitting end has a high modulation bandwidth. The red quantum well employs a wide-well structure of 3-5 nm, which increases the effective thickness of the absorption layer to improve the capture rate of blue photons and reduces the binding of photogenerated carriers by the potential barrier, thereby obtaining a higher escape probability under low bias voltage and significantly improving the external quantum efficiency and responsivity of the sensor.

[0044] Therefore, in the red-blue dual quantum well structure, the blue light emitted by the light-emitting unit A, after being modulated by the salt solution, is efficiently absorbed and converted by the red light quantum well in the receiver PD. This amplifies the weak light intensity changes caused by salinity and converts them into a more significant electrical signal, thereby greatly improving the sensitivity and signal-to-noise ratio of salinity detection. Through the synergistic optimization of the quantum well thickness and spatial distribution, not only can the responsivity of the detector to the blue light signal be further improved, but the high-speed response characteristics of the device can also be improved while ensuring luminous efficiency, thus achieving synergistic optimization of emission and detection performance.

[0045] like Figure 4 As shown, in terms of temperature detection, the detection unit B is set to a forward bias state. A 1 mA forward bias current is applied to the detection unit B through a second constant current drive source, and its forward voltage change is measured by the voltage measurement circuit of the electrical detection module. The temperature information is obtained through the central processing and control unit (with a built-in temperature-salt matrix decoupling algorithm module) of the signal processing module. The detection unit B exhibits weak light emission characteristics in the forward bias temperature measurement mode, thus forming a controlled optical coupling environment with the light-emitting unit A. The electrical response signal in this environment includes temperature drift and residual light interference, which can be extracted with high precision through a preset decoupling algorithm.

[0046] As the ambient temperature changes, the carrier concentration distribution inside detection unit B alters, reducing the free electron concentration difference between quantum well layers and narrowing the space charge region. Consequently, the forward voltage required to maintain the same operating current decreases with increasing temperature. By monitoring this change in forward voltage, real-time measurement of the device temperature is achieved.

[0047] Furthermore, since temperature changes are usually accompanied by changes in the physical properties of the measured liquid or environment, it can also be used to monitor temperature change processes caused by thermal effects in chemical reactions, biological reactions, or microscale systems, providing a technical basis for multi-parameter environmental sensing.

[0048] By pre-setting high-speed switching timing logic in the switching unit, the detection unit alternately switches between the first time slot in the zero-bias or reverse-bias state and the second time slot in the forward-bias state, which can realize real-time synchronous detection of temperature and salinity within one detection cycle.

[0049] In the first time slot, the drive control module sets the detection unit B to a zero-bias or reverse-bias state, acquiring the primary photocurrent signal excited by the incident light from the light-emitting unit A. This signal primarily characterizes the salinity information of the medium under test. In the subsequent second time slot, the drive control module applies a constant forward drive current (e.g., 1 mA) to the detection unit B, measuring the forward voltage drop across its terminals. This voltage drop signal directly characterizes the real-time temperature of the device. The switching frequency between the first and second time slots is preferably 10 Hz to 1 kHz, much higher than the rate of change of environmental parameters (temperature, salinity), thus achieving synchronous sensing of temperature and salinity parameters on a macroscopic time scale. Furthermore, the signal processing module incorporates a linear decoupling matrix, using the measured real-time temperature value to compensate and correct the photocurrent signal acquired in the first time slot, eliminating interference from temperature-induced carrier dynamics changes on the salinity measurement signal, and ultimately decoupling and outputting accurate temperature and salinity measurement results.

[0050] In one embodiment, the temperature and salt detection method using the aforementioned temperature and salt sensing device based on red-blue dual quantum well Micro-LED integrates the aforementioned temperature and salt sensing device based on red-blue dual quantum well Micro-LED into a microfluidic system, such as... Figure 5 As shown, the back side of the sapphire substrate 1 is brought into direct contact with the liquid in the microfluidic channel. The microfluidic channel is used to introduce a continuously flowing liquid, which enables continuous real-time monitoring of the flowing liquid.

[0051] The temperature and salinity detection method includes a detection cycle:

[0052] The detection unit is set to a zero-bias or reverse-bias state, driving the light-emitting unit to emit light signals. The light signals are reflected to the detection unit through the interface between the sapphire substrate and the liquid to be tested. The photocurrent signal generated by the detection unit is collected, and the salinity information of the liquid to be tested is determined by the photocurrent signal.

[0053] Switch the detection unit to the forward bias state and apply a forward bias constant current. Use the forward voltage signal of the detection unit to determine the temperature information.

[0054] By monitoring the photocurrent signal in real time, continuous sensing of changes in the refractive index of liquids in microfluidic systems can be achieved. This is suitable for online monitoring of refractive index changes caused by variations in liquid composition during chemical reactions, solution mixing, or biological sample processing. Depending on the specific needs, individual monitoring of temperature or refractive index changes can also be performed.

[0055] The above embodiments are only used to further illustrate the temperature and salt sensing device and temperature and salt detection method based on red and blue dual quantum well Micro-LED of the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A temperature-salinity sensing device based on red-blue dual quantum well Micro-LEDs, characterized in that, It includes composite sensor devices, drive control modules, electrical detection modules, and signal processing modules; The composite sensor includes a light-emitting unit and a detection unit spaced apart on the front side of a sapphire substrate; the light-emitting unit and the detection unit have the same GaN-based Micro-LED epitaxial structure, including an n-type layer, a blue quantum well region, a red quantum well region and a p-type layer arranged sequentially in the vertical direction; the back side of the sapphire substrate is in contact with the liquid to be tested and forms an optical coupling transmission path between the light-emitting unit and the detection unit. The drive control module is used to drive the light-emitting unit and switch the working state of the detection unit. The detection unit is used to generate a photocurrent signal in the zero bias or reverse bias state and to generate a temperature-sensitive electrical signal in the forward bias state. The electrical detection module is used to acquire the photogenerated current signal and the temperature-sensitive electrical signal; The signal processing module determines the salinity information of the liquid under test based on the photocurrent signal and the temperature information based on the temperature-sensitive electrical signal.

2. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 1, characterized in that: The drive control module includes a first constant current drive source, a switching unit, and a second constant current drive source; the first constant current drive source is used to drive the light-emitting unit to emit light signals; the switching unit is used to switch the bias state of the detection unit, wherein the detection unit is driven by the second constant current drive source in the positive bias state.

3. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 2, characterized in that: The switching unit presets high-speed switching timing logic, which causes the detection unit to alternately switch between the first time slot in the zero-bias or reverse-bias state and the second time slot in the positive-bias state.

4. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 3, characterized in that: The switching frequency between the first time slot and the second time slot is 10 Hz to 1 kHz.

5. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 1, characterized in that: The thickness of the well layer in the red quantum well region is greater than that in the blue quantum well region.

6. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 5, characterized in that: The thickness of the well layer in the red quantum well region is 3-5 nm, and the thickness of the well layer in the blue quantum well region is 2-3 nm.

7. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 1, characterized in that: The signal processing module has a built-in linear decoupling matrix, which compensates and corrects the photocurrent signal using the temperature information.

8. The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED according to claim 1, characterized in that, The method for fabricating the composite sensor includes: A GaN-based Micro-LED epitaxial structure comprising an n-type layer, a blue quantum well region, a red quantum well region, and a p-type layer in sequence is formed on the sapphire substrate by a single epitaxial process. Etching the GaN-based Micro-LED epitaxial structure to form the spaced light-emitting unit and detector unit; Extraction electrodes are fabricated on the light-emitting unit and the detection unit, respectively.

9. A method for detecting temperature and salinity, characterized in that: The temperature and salinity sensing device based on red-blue dual quantum well Micro-LED as described in any one of claims 1 to 8, wherein the temperature and salinity detection method includes, within one detection cycle: The detection unit is set to a zero-bias or reverse-bias state, and the light-emitting unit is driven to emit light signals. The light signals are reflected to the detection unit through the interface between the sapphire substrate and the liquid to be tested. The photocurrent signal generated by the detection unit is collected, and the salinity information of the liquid to be tested is determined through the photocurrent signal. The detection unit is switched to a forward bias state and a forward bias constant current is applied. The temperature information is determined by using the forward voltage signal of the detection unit.

10. The temperature and salinity detection method according to claim 9, characterized in that: The back side of the sapphire substrate is bonded to a microfluidic channel, which forms a continuous flow channel for the liquid to be tested.

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