Multipath optical sensor integrating time division multiplexing and frequency multiplexing schemes

Abstract

The invention belongs to the technical field of optical sensors, and particularly relates to a multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes, which comprises a sensing chip consisting of a plurality of groups of time division multiplexing sensing structure units, each group of time division multiplexing sensing structure unit consists of a plurality of groups of cascade double-ring structures, the sensing chip is embedded in the microfluidic channel device; the scanning input optical system based on the galvanometer is used for sequentially inputting a light source to the input ends of the multiple groups of time division multiplexing sensing structure units; the multi-path signal generator is electrically connected with the sensing chip and is used for applying resonance voltage signals with different frequencies to the cascade double-ring structures and distinguishing optical signals output by multiple groups of cascade double-ring structures in a frequency domain; the photoelectric detector is used for receiving an optical signal output by the cascade double-ring structure; the photoelectric detector is electrically connected with the signal receiving and processing system and used for signal demodulation and analysis. According to the invention, a mode of combining time division multiplexing and frequency multiplexing is used, so that the integration level of a chip and the expansibility of multi-channel sensing detection are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensors, and in particular relates to a multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes. Background Art

[0002] With the development of science and technology, Lab-on-a-Chip technology has shown great application potential in biomedical research, clinical diagnosis, environmental monitoring and other fields due to its advantages such as high integration, simple operation and low sample consumption.

[0003] In order to further improve the functionality and efficiency of the lab-on-a-chip and meet more complex experimental needs, new requirements for miniaturization, high precision and multi-functions are put forward for optical sensing systems. As the demand for sensing detection continues to increase, sensor chips are moving towards multiplexing to achieve simultaneous measurement of multiple parameters on the same platform, improve detection efficiency and performance, and improve data richness and detection accuracy. Common multiplexing schemes currently used on sensor chips include: multi-light source input, power division multiplexing and wavelength division multiplexing.

[0004] However, multi-light source input requires multiple lasers to work simultaneously, which is too costly and is not conducive to the development of integration and system miniaturization; the power division multiplexing scheme reduces the number of input light sources at the expense of optical path transmission loss, but due to loss limitations, it is impossible to achieve 16-channel or more multiplexing, which is not conducive to the further development of integration; in the wavelength division multiplexing scheme, each channel occupies a certain wavelength bandwidth, which limits the expansion of multiple channels. In summary, the above multiplexing schemes are not conducive to the further expansion of multiplexing. Summary of the invention

[0005] In view of this, the present invention provides a multi-channel optical sensor that integrates time division multiplexing and frequency multiplexing schemes, and uses time division multiplexing and frequency multiplexing to achieve multiplexing and multi-parameter measurement, so that the chip structure is compact, the space occupancy rate is improved, and more sensing structures can be accommodated, thereby improving the scalability of multiplexing, improving the efficiency and performance of detection, and at the same time improving the richness of data and the accuracy of detection.

[0006] The technical solution of the present invention is:

[0007] A multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes, comprising: a scanning input optical system based on a galvanometer, a sensor chip, a microfluidic channel device, a multi-channel signal generator, a photodetector and a signal receiving and processing system;

[0008] Among them, the sensor chip is composed of multiple groups of time-division multiplexing sensor structure units, each group of time-division multiplexing sensor structure units is composed of multiple groups of cascaded double-ring structures, the sensor chip is embedded in a microfluidic channel device, and the microfluidic channel device is used to realize the inflow and outflow of the liquid to be tested on the sensor chip; the galvanometer-based scanning input optical system is used to input the light source into the input end of the multiple groups of time-division multiplexing sensor structure units in sequence; the multi-channel signal generator is electrically connected to the sensor chip, and is used to apply resonant voltage signals of different frequencies to the cascaded double-ring structure, and distinguish the optical signals output by the multiple groups of cascaded double-ring structures in the frequency domain; the photodetector is used to receive the optical signal output by the cascaded double-ring structure and convert it into an electrical signal; the photodetector is electrically connected to the signal receiving and processing system, and is used to receive the electrical signal and perform demodulation and analysis.

[0009] Furthermore, each group of time-division multiplexing sensing structure units of the sensor chip is arranged at equal intervals, and each group of time-division multiplexing sensing structure units is composed of an input grating coupler, a Y-branch structure and multiple groups of cascaded double-ring structures connected in sequence, and each group of cascaded double-ring structures includes a sensing ring, a reference ring and an output grating coupler connected in sequence, the sensing ring is connected to the Y-branch structure, and a thermode is deposited above the reference ring. The thermode is used to receive resonant voltage signals of different resonant frequencies applied by a multi-channel signal generator, thereby transferring the original signals of sensor rings of different channels to different frequency domains.

[0010] Furthermore, the change in effective refractive index caused by the voltage modulation signal applied to the reference ring is less than 10 -4 , greater than 10 -6 .

[0011] Furthermore, the galvanometer-based scanning input optical system includes a tunable laser, a laser collimator, a semi-transparent and semi-reflective lens, a MEMS scanning galvanometer and a focusing concave mirror, wherein the tunable laser, laser collimator, semi-transparent and semi-reflective lens, and MEMS scanning galvanometer are located on the same optical axis, the angle of the MEMS scanning galvanometer on a two-dimensional plane is adjustable, and the focusing concave mirror is used to focus light of different deflection angles emitted by the MEMS scanning galvanometer into the input grating coupler of the multiple groups of time-division multiplexing sensing structure units of the sensor chip.

[0012] Furthermore, the MEMS scanning galvanometer is electrically connected to an external driving control system to achieve an adjustable angle of the MEMS scanning galvanometer on a two-dimensional plane.

[0013] Furthermore, the equivalent focal length f of the laser collimator is c satisfy:

[0014]

[0015] Among them, fc is the equivalent focal length of the laser collimator, ω output is the beam waist radius output from the laser collimator, λ is the wavelength, and MFD is the mode field diameter.

[0016] Furthermore, the focal length f of the focusing concave mirror is foc satisfy:

[0017]

[0018] Among them, f foc is the focal length of the focusing concave mirror, d is the radius of the collimated laser beam, ω p is the coupling spot diameter, and λ is the wavelength.

[0019] Furthermore, an optical power meter is arranged on one side of the semi-transparent and semi-reflective lens, and a first waveguide reflector and a second waveguide reflector are respectively arranged at the head and tail of the input grating coupler of the sensor chip, which are used to output the laser emission. The reflected laser light beam passes through the focusing concave mirror, MEMS scanning galvanometer and semi-transparent and semi-reflective lens in sequence, and is received by the optical power meter. The coupling effect is judged by the size of the optical power and the positioning of the structure on the sensor chip is realized.

[0020] Compared with the prior art, the present invention provides a multi-channel optical sensor that integrates time-division multiplexing and frequency-division multiplexing solutions, which uses a sensor chip composed of multiple groups of time-division multiplexing sensor structure units to realize information collection of the liquid to be tested. Each group of time-division multiplexing sensor structure units on the sensor chip is composed of multiple groups of cascaded double-ring structures. The scanning input optical system based on the galvanometer is used to input the light source to the input end of the multiple groups of time-division multiplexing sensor structure units in sequence. The multi-channel signal generator is electrically connected to the sensor chip and is used to apply resonant voltage signals of different frequencies to the cascaded double-ring structure to distinguish the optical signals output by the multiple groups of cascaded double-ring structures in the frequency domain. The photodetector is used to receive the optical signal output by the cascaded double-ring structure. The photodetector is electrically connected to the signal receiving and processing system for signal demodulation and analysis. The above structure has the following beneficial effects:

[0021] 1. The present invention uses time division multiplexing and frequency multiplexing to achieve multi-channel sensor detection, making the chip structure compact, increasing the space occupancy rate, and accommodating more sensor structures, thereby improving the scalability of multiplexing.

[0022] 2. The present invention realizes the automation of the measurement process through the design of the external drive control system and the signal receiving and processing system. Automatic scanning and automatic light alignment greatly improve the measurement efficiency, reduce the operation complexity, and make the equipment more user-friendly.

[0023] 3. The present invention uses a MEMS scanning galvanometer to accurately control the scanning of the laser beam in a two-dimensional plane, ensuring that the laser is accurately coupled to the input grating coupler of each sensing structure unit of the sensor chip. This high-precision scanning and positioning capability enables the optical sensor to achieve high accuracy and repeatability during the detection process.

[0024] 4. The present invention integrates microfluidic channel devices and a sensor chip designed with multiple sensor structure units, which can realize simultaneous measurement of multiple parameters of the sample to be tested, which is of great significance for the analysis and rapid screening of complex samples, can provide more comprehensive detection data, and improve the efficiency and quality of detection.

[0025] 5. The present invention integrates key parts such as the galvanometer scanning input optical system, sensor chip, microfluidic channel device, etc. into a miniaturized device, which only requires a light source and a photodetector, saving the cost of the system. The miniaturized design not only reduces the space and cost of the equipment, but also makes the equipment easy to carry and use, meeting the needs of rapid on-site detection. It is highly practical and worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0027] Figure 2 This is a chip structure diagram of the present invention.

[0028] Figure 3 It is the light path simulation diagram and the simulation light spot diagram of the present invention.

[0029] Figure 4 Schematic diagram of a single cascaded double ring structure of the present invention.

[0030] Figure 5 It is a simulation diagram of the transmission spectrum of the reference ring of the present invention and its first-order and second-order derivatives.

[0031] Figure 6 This is a simulation result diagram of the original signal and the demodulated signal of a single sensing structure of the present invention.

[0032] Figure 7 It is a simulation result diagram of the original signal and the demodulated signal of multiple groups of sensing structures of the present invention. DETAILED DESCRIPTION

[0033] The present invention provides a multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes. Figures 1 to 4The structural diagram of the present invention is used to illustrate the present invention. Among them, in the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, such as A and / or B, which can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two. The following terms "first" and "second" are used for descriptive purposes only and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0034] Example 1

[0035] like Figure 1 As shown, the present invention provides a multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes, including a scanning input optical system based on a galvanometer, a sensor chip 7, a multi-channel signal generator 8, a microfluidic channel device 9, a photodetector 10 and a signal receiving and processing system 12. Among them, the sensor chip 7 is composed of multiple groups of time division multiplexing sensor structure units, each group of time division multiplexing sensor structure units is composed of multiple groups of cascaded double-ring structures, the sensor chip 7 is embedded in the microfluidic channel device 9, the microfluidic channel device 9 is used to realize the inflow and outflow of the liquid to be measured on the sensor chip 7, the scanning input optical system based on the galvanometer is used to input the light source to the input end of the multiple groups of time division multiplexing sensor structure units in sequence, the multi-channel signal generator 8 is electrically connected to the sensor chip 7, and is used to apply resonant voltage signals of different frequencies to the cascaded double-ring structure, and distinguish the optical signals output by the multiple groups of cascaded double-ring structures in the frequency domain, the photodetector 10 is used to receive the optical signals output by the cascaded double-ring structure, and the photodetector 10 is electrically connected to the signal receiving and processing system 12 for signal demodulation and analysis.

[0036] Specifically, the sensor chip 7 is composed of multiple groups of time-division multiplexing sensor structure units, and the scanning input optical system based on the galvanometer is located obliquely above the sensor chip 7. The light source is sequentially input to different positions of the sensor chip 7 through galvanometer scanning, and the different positions correspond to the various input ends of the time-division multiplexing sensor structure unit. The time-division multiplexing sensor structure unit is composed of multiple groups of cascaded double-ring structures, and a multi-channel signal generator 8 is used to apply resonant voltage signals of different frequencies to the cascaded double-ring structures, so as to distinguish the optical signals output by the multiple groups of cascaded double-ring structures in the frequency domain.

[0037] like Figure 2 As shown, each group of time-division multiplexing sensing structural units of the sensor chip 7 is arranged at equal intervals, and each group of time-division multiplexing sensing structural units is composed of an input grating coupler 72, a Y branch structure 71 and a plurality of groups of cascaded double-ring structures connected in sequence, as shown in FIG. Figure 4As shown, each group of cascaded dual-ring structures includes a sensing ring 74, a reference ring 73 and an output grating coupler 75 connected in sequence. The sensing ring 74 is connected to the Y-branch structure 71. A thermode 76 is deposited above the reference ring 73. The thermode 76 is used to receive resonant voltage signals of different resonant frequencies applied by a multi-channel signal generator 8, thereby transferring the original signals of the sensing rings 74 of different channels to different frequency domains.

[0038] The structure of the scanning input optical system based on the galvanometer includes a tunable laser 1, a laser collimator 2, a semi-transparent and semi-reflective lens 3, a MEMS scanning galvanometer 5, a focusing concave mirror 6 and an external drive control system 11. The tunable laser 1, the laser collimator 2, the semi-transparent and semi-reflective lens 3, and the MEMS scanning galvanometer 5 are located on the same optical axis, the angle of the MEMS scanning galvanometer 5 on the two-dimensional plane is adjustable, and the focusing concave mirror 6 is used to focus the light of different deflection angles emitted by the MEMS scanning galvanometer 5 into the input grating coupler 72 of the multiple groups of time-division multiplexing sensing structure units of the sensor chip 7.

[0039] The time division multiplexing scheme of the multi-channel optical sensor of the present invention is realized by a scanning input optical system based on a galvanometer. The MEMS scanning galvanometer 5 is electrically connected to the external drive control system 11, and can realize two-dimensional angle deflection under the adjustment of the external drive control system 11, and can sequentially couple the laser to the input grating coupler 72 of the multiple groups of time division multiplexing sensor structure units of the sensor chip 7, so as to realize time division multiplexing between the multiple groups of time division multiplexing sensor structure units. The range of the deflection angle covers the input grating coupler 72 of the multiple groups of time division multiplexing sensor structure units of the sensor chip 7.

[0040] The tunable laser 1 emits a laser, which is collimated by the laser collimator 2 and then irradiated onto the MEMS scanning galvanometer 5 after passing through the semi-transparent and semi-reflective lens 3. The MEMS scanning galvanometer 5 is driven by the output voltage of the external drive control system 11 to change the angle in the x and y directions respectively, and the input light beam is scanned and input in sequence. The laser beam is then focused onto the input grating coupler 72 on the sensor chip 7 through the focusing concave mirror 6. The diameter of the focusing spot of the input grating coupler 72 is about 25 μm, which is slightly smaller than the size of the input grating coupler 72, thereby reducing coupling loss and achieving efficient optical signal coupling.

[0041] The laser beam is collimated after passing through the laser collimator 2. In order to ensure the collimation effect of the laser collimator 2 on the laser beam, the equivalent focal length of the laser collimator 2 needs to be calculated. The equivalent focal length f of the selected laser collimator 2 is c is 10 mm, and the beam waist radius ω output from the laser collimator 2 output The expression is:

[0042]

[0043] Among them, ω output is the waist radius of the beam output from the laser collimator 2, λ is the wavelength, and f c is the equivalent focal length of the laser collimator 2, and MFD is the mode field diameter.

[0044] Here, when the mode field diameter is 10 μm and λ is 1.55 μm, ω is calculated to be output It is 0.987mm.

[0045] The Rayleigh length z of the laser beam R The expression is

[0046]

[0047] Calculate the Rayleigh length z R It is 1947.5mm.

[0048] The distance z from the exit of the laser collimator 2 to the focusing concave mirror 6 is about 35 mm. Therefore, when the laser beam reaches the focusing concave mirror 6, the radius d of the laser beam is about

[0049]

[0050] The radius d of the laser beam and the beam waist radius ω output The values ​​are close, the radius d of the laser beam is almost unchanged, the collimation effect is good, and the focal length of the laser collimator 2 is appropriately selected, so the laser beam can be equivalent to a collimated beam.

[0051] The laser beam is coupled into the input grating coupler 72 through the focusing concave mirror 6. In order to focus the laser beam to a suitable size to obtain a higher coupling efficiency, the focusing concave mirror 6 should be selected according to the wavelength λ, the radius d of the input collimated laser beam, and the coupling spot diameter ω. p To determine the focal length f foc Since the size of the input grating coupler 72 is 30 μm × 40 μm, the coupling spot diameter ω is set p is 25μm.

[0052]

[0053] Among them, f foc is the focal length, d is the radius of the collimated laser beam, ω p is the coupling spot diameter, and λ is the wavelength.

[0054] Since the incident light is deflected at an angle, coma will be formed. Currently, the most common method to reduce coma is to use aspherical mirrors, but the cost is high.

[0055] like Figure 3Shown is a simulation diagram of a spatial light beam. The left picture is a schematic diagram of light beam propagation, and the right picture shows the light spots projected by the light beams at the center and the outermost edge. The light spots at the edge produce coma but their spot radius basically meets the coupling requirements, which will lead to a decrease in the coupling efficiency of the light beam, but it can still be used normally by the system.

[0056] When the light beam is focused onto the sensor chip 7 through the spatial optical system, the mechanical structure design ensures that the position of the focused spot on the sensor chip 7 is near the position of the input grating coupler 72. Therefore, it is only necessary to fine-tune the position of the focused spot so that the spatial input light can be coupled into the sensor chip 7 through the input grating coupler 72.

[0057] like Figure 2 As shown, the first waveguide reflector 77 and the second waveguide reflector 78 are designed at the head and tail of the input grating coupler 72 on the sensor chip 7. During the optical calibration process, we achieve coupling by monitoring the reflected light of the first waveguide reflector 77 and the second waveguide reflector 78. Figure 1 and Figure 2 As shown, the light beams returned by the first waveguide reflector 77 and the second waveguide reflector 78 pass through the focusing concave mirror 6, the MEMS scanning galvanometer 5 and the semi-transparent and semi-reflective lens 3 in sequence, and then the optical signal is received by the optical power meter 4 arranged on one side of the semi-transparent and semi-reflective lens 3. The optical power feedback from the optical power meter 4 is used to judge the coupling effect and realize the positioning of the structure on the sensor chip 7.

[0058] First, adjust the x direction of the MEMS scanning galvanometer 5 so that the optical power meter 4 receives a significant light intensity signal and records V x Then adjust the y direction of the MEMS scanning galvanometer 5 so that the optical power meter 4 receives the strongest light intensity signal and records V at this time. y After repeated fine-tuning in the x and y directions, the maximum light intensity signal is obtained and the voltage at this time is recorded as V x0 and V y0 , corresponding to the position of the first waveguide reflector 77. In the same way, the coupling voltages corresponding to the second waveguide reflector 78 on the other side are V x33 and V y33 The position of each input grating coupler 72 is defined by the driving voltage value of the galvanometer. Since two points determine a straight line and the spacing between each input grating coupler 72 is a constant, the voltage coordinates of the multi-channel input grating coupler 72 can be calculated based on the voltage coordinates of the two first waveguide reflectors 77 and the second waveguide reflector 78. x and V yThe voltage positioning value corresponding to each input grating coupler 72 is adjusted in turn, and the filter stays on each input grating coupler 72 for the filter scanning time t1 to complete a single test, and then moves to the next input grating coupler 71 after the moving time t2. The scanning and spectrum testing of all input grating couplers 71 are completed in turn, and then the scan is moved to the initial position for a cycle, so as to monitor the spectrum change process of the biosensor.

[0059] The use of a focusing concave mirror 6 instead of a lens for focusing the laser beam is to further reduce the overall size of the optical system. In the optical system, after the laser beam is output from the laser collimator 2, it is incident on the MEMS scanning galvanometer 5 at an angle of 22.5°. The mirror diameter of the MEMS scanning galvanometer 5 is 3mm. After coating, its reflectivity for the C band is greater than 98%. By applying a voltage of -10V to 10V, an angle deflection of -5.6° to 5.6° can be achieved in the x and y directions, respectively.

[0060] like Figure 2 As shown, the laser input into the input grating coupler 72 in each group of time-division multiplexing sensor structure units of the sensor chip 7 is split by the Y-branch structure 71 and then connected to multiple groups of cascaded double-ring structures. The signal distinction of each group of cascaded double-ring structures is achieved by using a multi-channel signal generator 8 to apply voltage signals of different resonant frequencies to the hot electrode 76. The original signals of the sensor rings 74 of different channels can be transferred to the frequency domain to achieve the distinction of multiple laser signals.

[0061] A single cascade double ring structure such as Figure 4 As shown, by applying voltage to the hot electrode 76 of the reference ring 73, the effective refractive index of the waveguide will be changed due to the thermal effect. When the applied voltage is a resonant signal V0sin(2πωt), the spectrum of the reference ring 73 will resonate and drift synchronously with the applied resonant voltage signal. For each cascaded double-ring structure, a multi-channel signal generator 8 applies voltage signals V0sin(2πω1t), V0sin(2πω2t), V0sin(2πω3t), ... of different resonant frequencies to the hot electrode 76, so that the original signals of the sensing rings 74 of different paths can be transferred to the frequency domain. At the output end, a photodetector 10 is used to complete the detection of all output signals. The resonant frequency signal corresponding to each path is multiplied by the output signal, and the sensing signal of each path can be restored after low-pass filtering. Therefore, a tunable laser 1 input and a photodetector 10 can be used to complete the signal input and signal reception, which simplifies the instruments used in experimental tests and saves costs.

[0062] The specific theory is as follows: According to the transmission matrix, the drop end transmission spectrum T of the sensor ring 74 is sen The expression is

[0063]

[0064] Among them, the transmission constant β1 = k0·n eff1 , Central wavelength λ0=1.55μm,n eff1 is the effective refractive index of the TM mode, k1 is the coupling coefficient between the ring and the waveguide, t1 is the transmission coefficient, α R1 is the transmission loss of the sensing ring 74 , and R1 is the radius of the sensing ring 74 .

[0065] For the reference ring 73, the power of the input light P in for

[0066] P in =P source ·T sen

[0067] Among them, P source is the input light source power, T sen is the drop end transmission spectrum of the sensing ring 74.

[0068] Transmission spectrum T of the drop end of reference ring 73 ref The expression is

[0069]

[0070] Among them, k2 is the coupling coefficient between the ring and the waveguide, t2 is the transmission coefficient, and α R2 is the transmission loss of the reference ring 73, R2 is the radius of the reference ring 73, and the transmission constant β2 = k0·n eff2 , n eff2 Affected by the thermal effect of the applied voltage, the applied resonant voltage is V0sin(2πωt), V0 is the amplitude of the applied voltage, ω is the modulation frequency, and the thermal modulation efficiency is m. The expression of the effective refractive index is Among them, n eff0 is the original effective refractive index, Δn eff is the change in refractive index.

[0071] The light modulated by the reference ring 73 is P out , for which n eff0 Taylor expansion

[0072]

[0073] The expansion includes constant terms, first-order terms, and second-order terms. Since the higher-order terms are small, they are ignored. Figure 5 are the output spectrum T of the drop end of the reference ring 73 ref , first-order derivative and the second-order derivative

[0074] The chip design is based on the SOI platform, with a waveguide height of 220nm and a width of 550nm. Other parameters used in the simulation are shown in Table 1:

[0075] Table 1 Main parameters of device design on silicon-based chip

[0076]

[0077] like Figure 6 (a) shows the drop-end sensing spectrum of the sensor ring 74 with a radius of 125 μm, that is, the original signal. After the resonant voltage is modulated, the optical signal P output by the output grating coupler 75 is out , and cos(2πω de t) and then low-pass filtered. The signal obtained at this time is the first-order derivative of the transmission spectrum of the reference loop 73. Therefore, the filtered result is divided by the first-order derivative The original signal can be restored.

[0078] However, considering that the Taylor expansion also contains the second-order derivative In order to avoid the interference of the second-order derivative on the restoration result, it is necessary to ensure For a small amount, Therefore, it is required that the change in effective refractive index caused by the voltage modulation signal on the reference ring 73 is less than 10 -4 , greater than 10 -6 When the resonant voltage with a modulation frequency of ω = 100 Hz is applied to the reference loop 73, the output optical signal P out and cos(2πω de t) and use ω de =200Hz and ω de = 240Hz, restore and low-pass filter, divide by the first-order derivative After that, the restored signal obtained in the simulation is as follows Figure 6 (b) As shown. Therefore, it can be seen that the original signal can be restored by demodulating with the corresponding frequency, while the original signal cannot be restored with the non-corresponding frequency. eff =0.00001, at this time, the second-order derivative term has little effect on the restoration of the signal, and there are a small number of stray waves, but it does not affect the basic resonance information of the original signal.

[0079] like Figure 7 (a) shows the effective refractive index n of the sensor ring 74 eff1The three signals are divided into 1.746, 1.7463, and 1.7466. The three signals are modulated by voltage signals with frequencies of 100, 110, and 120 Hz, respectively, and then demodulated by frequencies of 200, 220, and 240 Hz, respectively. Figure 7 As shown in (b), the signal of each channel can be restored.

[0080] The sensor chip 7 is embedded in the microfluidic channel device 9, which is used for the inflow and outflow of the biological sample solution to be tested at the sensing ring 74 detection window of the sensor chip 7. The multi-channel design of the microfluidic channel device 9 allows the detection of multiple samples at the same time, so as to improve the detection efficiency. When the sensor chip 7 performs biospecific sensing, different specific biofilm modifications can be performed on the sensing areas of different sensing units to achieve multi-parameter detection of the sample to be tested.

[0081] The photodetector 10 is inverted on the upper side of the sensor chip 7, and is used to receive the multi-path optical signals output by the output grating coupler 75 of the sensor chip 7. The photodetector 10 is electrically connected to the signal receiving and processing system 12, and is used to realize the analysis and processing of the optical signals, and distinguish the signals of each group of time-division multiplexing sensor structure units by the time period of signal transmission. By demodulating the signal using the corresponding demodulation frequency, the signals of multiple groups of cascaded dual-ring structures in a single time-division multiplexing sensor structure unit can be extracted respectively.

[0082] Furthermore, the signal receiving and processing system 12 also has a user interface function, which can display the measurement results to the user in an intuitive form such as digital readings, charts, etc., and supports data storage, export and remote transmission, facilitating further data analysis and sharing.

[0083] The present invention can use time division multiplexing and frequency multiplexing simultaneously to realize multiplexing and multi-parameter measurement.

[0084] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes, characterized in that: include: A scanning input optical system based on a galvanometer, a sensor chip (7), a microfluidic channel device (9), a multi-channel signal generator (8), a photodetector (10) and a signal receiving and processing system (12); The sensor chip (7) is composed of a plurality of groups of time-division multiplexing sensor structure units, each group of time-division multiplexing sensor structure units is composed of a plurality of groups of cascaded double-ring structures, the sensor chip (7) is embedded in a microfluidic channel device (9), and the microfluidic channel device (9) is used to realize the inflow and outflow of the liquid to be tested on the sensor chip (7); the scanning input optical system based on the galvanometer is used to input the light source to the input ends of the plurality of groups of time-division multiplexing sensor structure units in sequence; the multi-channel signal generator (8) is electrically connected to the sensor chip (7) and is used to apply resonant voltage signals of different frequencies to the cascaded double-ring structures to distinguish the optical signals output by the plurality of groups of cascaded double-ring structures in the frequency domain; the photoelectric detector (10) is used to receive the optical signals output by the cascaded double-ring structures and convert them into electrical signals; the photoelectric detector (10) is electrically connected to the signal receiving and processing system (12) and is used to receive the electrical signals and perform demodulation and analysis.

2. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 1, characterized in that: Each group of time-division multiplexing sensing structural units of the sensor chip (7) is arranged at equal intervals, and each group of time-division multiplexing sensing structural units is composed of an input grating coupler (72), a Y-branch structure (71) and a plurality of groups of cascaded double-ring structures connected in sequence, and each group of cascaded double-ring structures includes a sensing ring (74), a reference ring (73) and an output grating coupler (75) connected in sequence, the sensing ring (74) is connected to the Y-branch structure (71), and a hot electrode (76) is deposited above the reference ring (73), and the hot electrode (76) is used to receive resonant voltage signals of different resonant frequencies applied by a multi-channel signal generator (8), thereby transferring original signals of sensing rings (74) of different channels to different frequency domains.

3. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 2, characterized in that: The voltage modulation signal applied to the reference ring (73) causes a change in the effective refractive index of less than 10 -4 , greater than 10 -6 .

4. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 1, characterized in that: The scanning input optical system based on a galvanometer comprises a tunable laser (1), a laser collimator (2), a semi-transparent and semi-reflective lens (3), a MEMS scanning galvanometer (5) and a focusing concave mirror (6), wherein the tunable laser (1), the laser collimator (2), the semi-transparent and semi-reflective lens (3) and the MEMS scanning galvanometer (5) are located on the same optical axis, the angle of the MEMS scanning galvanometer (5) on a two-dimensional plane is adjustable, and the focusing concave mirror (6) is used to focus light of different deflection angles emitted by the MEMS scanning galvanometer (5) into the input grating coupler (72) of multiple groups of time-division multiplexing sensing structure units of the sensor chip (7).

5. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 4, characterized in that: The MEMS scanning oscillator (5) is electrically connected to an external drive control system (11) to achieve an adjustable angle of the MEMS scanning oscillator (5) on a two-dimensional plane.

6. A multi-channel optical sensor integrating time division multiplexing and frequency multiplexing schemes according to claim 4, characterized in that: The equivalent focal length f of the laser collimator (2) is c satisfy: Among them, f c is the equivalent focal length of the laser collimator (2), ω output is the beam waist radius output from the laser collimator (2), λ is the wavelength, and MFD is the mode field diameter.

7. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 4, characterized in that: The focal length f of the focusing concave mirror (6) is foc satisfy: Among them, f foc is the focal length of the focusing concave mirror (6), d is the radius of the collimated laser beam, ω p is the coupling spot diameter, and λ is the wavelength.

8. The multi-channel optical sensor integrating time division multiplexing and frequency multiplexing scheme according to claim 2, characterized in that: An optical power meter (4) is arranged on one side of the semi-transparent and semi-reflective lens (3), and a first waveguide reflector (77) and a second waveguide reflector (78) are arranged at the head and tail of the input grating coupler (72) of the sensor chip (7) respectively, for emitting laser light. The reflected laser light beam passes through the focusing concave mirror (6), the MEMS scanning galvanometer (5) and the semi-transparent and semi-reflective lens (3) in sequence, and is then received by the optical power meter (4). The coupling effect is judged by the size of the optical power and the positioning of the structure on the sensor chip (7) is achieved.

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