CN117470806A - Polymer glucose sensor based on Mach-Zehnder structure - Google Patents

Abstract

The invention discloses a polymer glucose sensor based on a Mach-Zehnder structure, which includes a PDMS lower cladding layer and a PMMA core layer arranged on the PDMS lower cladding layer. The PMMA core layer is a Mach-Zehnder structure pattern. GOD is fixed on the sensing arm of the PMMA core layer through an acidic coupling agent to form a three-dimensional rectangular contact. The polymer glucose sensor proposed by the present invention does not require external modulation means such as electro-optical light or thermal light. It can sense glucose in a wide concentration range only by measuring changes in output light power, and does not require long sensing arms and complex micro-electronics. Fluid control chip has the characteristics of simple device structure, compactness and high sensitivity.

Description

A polymer glucose sensor based on Mach-Zehnder structure

Technical field

The present invention relates to a glucose light sensing device, and in particular to a polymer glucose sensor based on a Mach-Zehnder structure, which can be used for glucose concentration measurement in a wide range.

Background technique

A glucose sensor is an instrument used to measure glucose concentration in the environment. It can help people understand the glucose concentration in the environment and better control their diet and lifestyle. Compared with traditional measurement methods, glucose sensors have the advantages of fast response, high sensitivity, and good stability, so they are widely used in fields such as food safety, biotechnology, and medical testing. For example, in food processing and manufacturing, glucose sensors can be used to detect the glucose content in food to ensure the quality and safety of food; in the agricultural field, glucose sensors can be used to detect the glucose content in soil to evaluate soil fertility and crop growth; in addition, in environmental monitoring, glucose sensors can also be used to detect glucose content in water bodies to assess the degree of pollution of water bodies and the health of the ecological environment.

Glucose monitoring instruments can be divided into wavelength measurement method and light intensity measurement method according to the sensing measurement method. The wavelength measurement method is based on the absorption or reflection spectral characteristics of a glucose solution at a specific wavelength to determine its concentration. This method not only requires the use of complex optical components, such as filters, gratings, or interferometers, but also requires precise wavelength measurement. equipment to achieve accurate measurements, which greatly increases the complexity and cost of the system. The wavelength shift of wavelength measurement methods may be small at certain concentrations, so their sensitivity is susceptible to the measurement accuracy of the spectrometer. The light intensity measurement method is a method of measuring changes in output light power intensity. This measurement solution does not require a spectrometer and greatly reduces the cost of measurement. Some sensors based on light intensity detection methods that have been reported so far have shortcomings such as limited sensitivity, complex and not compact structures, or high requirements for light sources. They have shortcomings such as fast response to the interaction between the substance to be measured and the sensor and a wide dynamic range. Certain shortcomings.

Therefore, how to explore an optical glucose measurement method and obtain a glucose sensor with high sensitivity, high linearity, high stability, and low detection limit on the premise of measuring glucose concentration with high precision is an urgent technical problem to be solved in this field. .

Explanation of terms: PDMS: polydimethylsiloxane; PMMA: polymethylmethacrylate; GOD: glucose oxidase; MMI: multimode interference coupler; PBS: phosphate.

Contents of the invention

The purpose of the present invention is to propose a polymer glucose sensor based on a Mach-Zehnder structure, which has high sensitivity, good linearity, strong stability and easy integration, and can effectively measure a wide range of glucose concentrations.

In order to achieve the above objects, the technical solution of the present invention is:

The invention provides a polymer glucose sensor based on a Mach-Zehnder structure, which includes a PDMS lower cladding layer, a PMMA core layer and a PDMS upper cladding layer from bottom to top; the PMMA core layer includes an input waveguide, an output waveguide, a 1×2 MMI coupler, 2×1 MMI coupler, curved waveguide, sensing arm and reference arm; the sensing arm and the reference arm are equal in length and parallel, and they are arranged symmetrically with the center line as the axis; through acidic water at a temperature of 40°C The coupling agent fixes GOD on the sensing arm of the PMMA core layer to form a three-dimensional rectangular contact structure. The upper surface of the three-dimensional rectangular contact structure is lower than the upper surface of the PDMS upper cladding layer and higher than the upper surface of the sensing arm;

The refractive index variation range of the GOD is 1.3352-1.3400, the arm length of the sensing arm is 1740µm, and the arm spacing between the sensing arm and the reference arm is 130µm; the bending radius of the curved waveguide is 800µm, and the curved waveguide The lateral length of the curved waveguide is 430µm, and the deflection angle of the curved waveguide is 0.28rad;

The loss of the polymer glucose sensor based on the Mach-Zehnder structure is controlled within 1.6dB, and the sensitivity is 2.67 mW/(mg/mL).

Preferably, the polymer glucose sensor based on Mach-Zehnder structure has a loss of 1.58dB and an extinction ratio of 41.43dB.

When the input light power is 10mW and the glucose solution concentration is 0mg/mL, the maximum output light power is 6.95mW, and when the glucose solution concentration is 2.6mg/mL, the minimum output light power is 0.0005mW, and the sensor achieves a glucose concentration of 0 -Linear response within the range of -2.6mg/mL, glucose concentration sensing range is 0-2.6mg/mL.

The relative standard deviation of the polymer glucose sensor based on the Mach-Zehnder structure is (1.5-2.5)×10 ^-3 , and the lowest detection limit is 0.1 mg/mL.

The thickness of the PDMS lower cladding layer and the PDMS upper cladding layer are both 10µm and the refractive index is 1.4040; the thickness of the PMMA core layer is 1µm and the refractive index is 1.4880; the distance from the upper surface of the sensing arm to the upper surface of the three-dimensional rectangular contact structure is 2-3µm.

Preferably, the waveguide width of the curved waveguide is 1.5µm and the height is 1µm.

The GOD solution is obtained by: dissolving GOD powder in PBS buffer with a pH of 5.5 to form a GOD solution with a mass concentration of 30 mg/mL;

The GOD solution is dropped on the sensing arm of the PMMA core layer and solidified to form a three-dimensional rectangular contact structure on the sensing arm.

Compared with the prior art, the beneficial effects of the present invention are:

1. The input optical power of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention is 10 mW, and the output optical power varies between 0.0005-6.9500 mW when the glucose solution concentration is 0-2.6 mg/mL. The length of the sensing arm of the present invention is 1740 µm, which greatly reduces the size of the device. The structure is simple and compact, and the measurement of a wide range of glucose solution concentrations can be achieved without the need for a long sensing arm and a complex microfluidic chip.

2. During the preparation of the glucose sensor of the present invention, by controlling the GOD temperature to 40°C and the pH to 5.5, GOD can be kept at optimal activity, so that the output optical power of the polymer glucose sensor with a Mach-Zehnder structure reaches the maximum value, and the sensitivity is 2.67 mW/ (mg/mL), and the loss is controlled within 1.6dB. It has the characteristics of high stability (relative standard deviation about (1.5-2.5)×10 ^-3 ) and low detection limit (0.1mg/mL).

Description of the drawings

Figure 1 is a schematic structural diagram of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 2 is a schematic diagram of the curved waveguide structure and parameters of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention; (a) is a diagram of the influence of lateral length on the change in output optical power under different deflection angles; (b) is a diagram of the change in output light power under deflection The influence of bending radius on the change of output optical power at an angle of 0.28rad;

Figure 3 is a comparison diagram of the output optical power of different arm spacings of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention; (a) is the arm spacing when the coupling effect occurs between the reference arm and the sensing arm (left picture) and the corresponding Output optical power (right picture); (b) is the arm spacing when no coupling effect occurs between the reference arm and the sensing arm (left picture) and the corresponding output optical power (right picture); (c) is different arm spacing Comparison chart of the change of output optical power with refractive index;

Figure 4 is a comparison diagram of the output light power response under different sensing arm lengths of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 5 is a light field diagram of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 6 is a schematic diagram of the measurement system of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 7 is a response diagram of the change in output light power of a polymer glucose sensor based on a Mach-Zehnder structure obtained at different temperatures and pH; (a) is a diagram of the influence of different temperatures on the output light power; (b) is Chart showing the influence of different pH on the output light power;

Figure 8 is a response diagram of the output optical power of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention as the glucose concentration changes;

Figure 9 is a specific response diagram of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 10 is a stability response diagram of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention;

Figure 11 is a durability response diagram of the polymer glucose sensor based on the Mach-Zehnder structure of the present invention; (a) is a comparison diagram of the output light power of the same polymer glucose sensor at different times and under different glucose concentrations; (b) is Comparison of sensitivity and loss of the same polymer glucose sensor at different times and different glucose concentrations;

Reference signs:

1. PDMS lower cladding, 2. PMMA core layer, 3. PDMS upper cladding, 4. 1×2 MMI coupler, 5. 2×1 MMI coupler, 6. Curved waveguide, 7. Sensing arm, 8 , reference arm, 9. input waveguide, 10. output waveguide, 11. centerline.

Detailed ways

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. The embodiments described below with reference to the drawings are exemplary. are only used to explain the technical solutions of the present invention and should not be understood as limitations of the present invention.

The structure of the polymer glucose sensor (polymer glucose sensor for short) based on the Mach-Zehnder structure in this embodiment is shown in Figure 1 . It includes PDMS lower cladding layer 1, PMMA core layer 2 and PDMS upper cladding layer 3 from bottom to top. PMMA core layer 2 includes input waveguide 9, output waveguide 10, 1×2 MMI coupler 4, 2×1 MMI coupler 5, curved waveguide 6, sensing arm 7 and reference arm 8, sensing arm 7 and reference arm 8 Set up axially symmetrically with the center line 11, etch the PDMS upper cladding 3 near the area where the sensing arm 7 is located, expose all the upper, left and right sides of the sensing arm 7, GOD fills the etched area and passes through the acidic The coupling agent is fixed on the sensing arm 7 of the PMMA core layer 2 to form a three-dimensional rectangular contact structure. The upper surface of the three-dimensional rectangular contact structure is lower than the upper surface of the PDMS upper cladding layer 3 and higher than the upper surface of the sensing arm 7 .

In this embodiment, the thickness of the PDMS lower cladding layer and the PDMS upper cladding layer are both 10µm, and the refractive index is 1.4040; the thickness of the PMMA core layer is 1µm, and the refractive index is 1.4880; the distance from the upper surface of the sensing arm to the upper surface of the three-dimensional rectangular contact structure The distance is 2-3µm.

The curved waveguide structure and parameters of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment are shown in Figure 2. When selecting the curved waveguide 6, a rectangular waveguide with a waveguide width of 1.5µm and a height of 1µm is selected for coupling and docking with the 1×2MMI coupler 4 at the front end. The bending radius, lateral length and deflection angle of the curved waveguide 6 are three important factors that have a greater impact on optical loss. (a) in Figure 2 shows the impact of the lateral length on the change in output optical power under different deflection angles. In deflection When the angle is 0.28rad, the output optical power loss is smaller and more stable. (b) in Figure 2 shows the effect of bending radius on the change in output optical power when the deflection angle is 0.28rad. When the deflection angle is 0.28rad and the lateral length is 430µm, the output optical power loss is the smallest when the bending radius is 800µm. And relatively stable. After comprehensive consideration, the present invention selects the bending radius of the curved waveguide 6 as 800µm, the lateral length as 430µm, and the deflection angle as 0.28rad. At this time, the waveguide loss of the curved waveguide 6 reaches a minimum value, and its normalized output optical power is 0.96a.u.

The comparison chart of the output optical power at different arm spacings of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 3. If the distance between the sensing arm 7 and the reference arm 8 is too close, the coupling effect will occur (the energy input by the left waveguide is gradually coupled to the right waveguide as the propagation distance increases), and it will also affect the sensing of the sensor. performance. When the arm spacing is not greater than 4µm, it can be seen from (a) in Figure 3 that the arm spacing is too close at this time, which will seriously affect the sensing performance of the sensor; comprehensively consider the bending radius, lateral length and deflection angle of the curved waveguide 6 Together with the arm spacing, it is determined that when the arm spacing is 130µm, there will be no coupling effect between the waveguides between the sensing arm 7 and the reference arm 8. As shown in (b) of Figure 3, the output optical power The maximum value can be reached, at which time the device loss is minimal, as shown in (c) of Figure 3.

The sensitivity S of the polymer glucose sensor based on the Mach-Zehnder structure can be expressed as:

,

In the formula, λ is the wavelength, L is the arm length of the sensing arm, n _c is the refractive index of the liquid to be measured, N _eff is the effective refractive index of the sensing arm, is the relationship between the effective refractive index of the sensing arm and the change of glucose concentration. Through formula analysis, it can be seen that not only the effective refractive index N _eff of the sensing arm will affect the sensitivity of the glucose sensor, but also the arm length L of the sensing arm will also affect its sensitivity. At the same time, the polymer glucose sensor that combines the refractive index and Mach-Zehnder structure Transmission power analysis, increasing the evanescent field range in which the light field contacts the object to be measured can also improve its sensing sensitivity. For the light-intensity Mach-Zehnder structure polymer glucose sensor, the light intensity will repeat twice in a change period, so only the light intensity response change of 1/2 period is considered.

After specifically catalyzing the glucose reaction, the refractive index of GOD decreases. After the catalytic reaction of glucose solutions with enzymes of different concentrations, the refractive index of the solution also decreases. In addition, the sensitivity and sensing range of the Mach-Zehnder structure polymer glucose sensor are a pair of mutually restrictive quantities. In this embodiment, the refractive index change range of GOD is set to 1.3352-1.3400, and the arm length of the sensing arm 7 is 1740µm. If the arm length continues to increase, the detected glucose concentration range will be reduced, and the refractive index change range of GOD is 1.3352. Within the range of -1.3400, its output optical power is not monotonous; similarly, if the arm length continues to increase, the sensitivity of detected glucose will decrease, and when the sensing arm 7 is a rectangular waveguide structure with three surfaces in contact with the object to be measured, When the arm spacing is 130µm, the bending radius of the curved waveguide 6 is 800µm, the lateral length is 430µm and the deflection angle is 0.28 rad, it has high sensitivity and linearity in this refractive index range, and ensures the maximum sensing range. At the same time, minimization of devices is achieved.

The comparison chart of the output light power response of the polymer glucose sensor based on the Mach-Zehnder structure under different sensing arm arm lengths in this embodiment is shown in Figure 4. When the refractive index change range of GOD is in the 1.3352-1.3400 interval, the output optical power difference at the end point of the interval is the largest and is monotonic in this interval, the sensitivity reaches the maximum. Only when the arm length of the sensing arm 7 is 1740µm, the GOD refractive index change range is in the interval 1.3352-1.3400 and the output optical power is monotonic in this interval; when the sensing arm length is less than 1740µm, the GOD refractive index change range The sensitivity in the 1.3352-1.3400 range will decrease and cannot meet the glucose detection requirements.

The light field diagram of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 5. When the arm length of the sensing arm 7 is 1740µm and the sensing arm 7 is a rectangular waveguide structure with three sides in contact with the object to be measured, the arm spacing is 130µm, the bending radius of the curved waveguide 6 is 800µm, the lateral length is 430µm and the deflection When the angle is 0.28rad, the light field is effectively limited to the PMMA core layer 2 area. At this time, the extinction ratio of the glucose sensor is 41.43dB.

The measurement system of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 6 . The polymer glucose sensor based on the Mach-Zehnder structure after silanization coupling modification of GOD is dripped with glucose solution for sensing measurement. The tunable laser emits light with a wavelength of 1550 nm through the polarization controller and then coupled into the tapered optical fiber. To the input waveguide 9 of the polymer glucose sensor based on the Mach-Zehnder structure, the input light interferes with the sensing arm 7 and the reference arm 8, and is coupled and output to the optical power meter by the output waveguide 10 through the tapered optical fiber, thereby obtaining the result based on The relationship between concentration and output light power of polymer glucose sensor with Mach-Zehnder structure.

In this embodiment, when fixing GOD, it is necessary to control the temperature and pH of the GOD, so as to optimize the performance of the polymer glucose sensor based on the Mach-Zehnder structure while maintaining the optimal activity of GOD.

This embodiment uses covalent coupling method to achieve simple, efficient and stable fixation of GOD. First, use a silane solution to functionalize the surface of the sensing arm 7, and use silane to build a "molecular bridge" between the interface of the enzyme and the polymer material; then use 1-(3-dimethylaminopropyl)-3 -The cross-linking agent composed of ethylcarbodiimide hydrochloride and N-hydroxysuccinimide further couples the surface of the sensing arm 7;

Dissolve GOD powder in PBS buffer with a pH of 5.5 to form a 30 mg/mL GOD solution. Place the device after etching the PDMS upper cladding layer 3 in a high and low temperature test chamber, and control the temperature to 40°C. Add GOD solution and solidify to form a three-dimensional rectangular contact structure on the sensing arm, and rinse the unfixed GOD on the surface of sensing arm 7 with PBS buffer to complete the fixation of GOD.

The response diagram of the change in output light power of the polymer glucose sensor based on the Mach-Zehnder structure obtained at different temperatures and pH in this example is shown in Figure 7 . The present invention controls the temperature to change between 35-45°C through a high and low temperature test chamber, uses glucose solutions of the same concentration, the same volume, and different temperatures to conduct experiments, and analyzes the optical transmission characteristic curve corresponding to the polymer glucose sensor based on the Mach-Zehnder structure. changes with temperature. The effect of temperature on optical transmission characteristics is shown in Figure 7 (a). When the temperature of GOD is increased to 40°C, the most intense specific catalytic reaction occurs on the surface of sensing arm 7, and the sensing arm 7 effectively refracts The rate change is the largest, so the output light power change reaches the maximum; further increasing the temperature value of the PBS buffer, the effective refractive index change of the sensing arm 7 will decrease, which will lead to the output light of the polymer glucose sensor based on the Mach-Zehnder structure. The amount of power variation is reduced.

In the present invention, the pH value of the PBS buffer solution with pH=4.0 and pH=8.0 is mixed with HCl and NaOH, controlled within a certain range, and measured by a pH meter, and then narrows the pH range at 0.5 pH intervals to find the optimum pH. Use glucose solutions of the same concentration, same volume, and different pH for drop measurement. The influence of the pH value of the solution on the optical transmission characteristics is shown in (b) of Figure 7. When the pH value of the PBS buffer is increased to 5.5, the active groups on the GOD molecules are in a dissociated state and occur on the surface of the sensing arm 7. After the specific catalytic reaction, the effective refractive index of the sensing arm 7 will change the most, so the output light power reaches the maximum change. Further increasing the pH value of the PBS buffer, the dissociation state of the active groups on the GOD molecule is inhibited, which is not conducive to the binding of enzyme and glucose. The effective refractive index change of the sensing arm 7 will be reduced, which will lead to the Mach-Zehnder structure-based The change in output light power of the polymer glucose sensor is reduced.

In order to test the sensing range and sensitivity of the polymer glucose sensor based on the Mach-Zehnder structure, glucose solutions with different concentrations of 0-3mg/mL were configured, and glucose solutions with different concentration gradients were configured at a concentration interval of 0.1mg/mL. Solution, for example, prepare a glucose solution with a concentration of 1 mg/mL. Add 10 mg of glucose powder to 10 mL of PBS buffer with a pH of 5.5 and stir evenly using a magnetic stirrer.

The response diagram of the output optical power of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment changes with the glucose concentration is shown in Figure 8. In the experimental measurement, an input optical power of 10 mW was used to measure the glucose concentration sensing range C _L of the polymer glucose sensor based on the Mach-Zehnder structure and its response ability to different concentrations of glucose. In order to eliminate the interference caused by glucose solutions of different concentrations each time, the sensing arm 7 needs to be rinsed with deionized water before each independent measurement. Figure 8 shows the optical output characteristics of the polymer glucose sensor based on the Mach-Zehnder structure under different glucose concentrations. As the concentration of the glucose solution increases, the output optical power changes in the direction of power reduction. Experimental results show that when the glucose solution concentration is 0mg/mL, the maximum output light power is 6.95mW, and when the glucose solution concentration is 2.6mg/mL, the minimum output light power is 0.0005mW. The device achieves a glucose concentration range of 0 Linear response within -2.6mg/mL. The polymer glucose sensor based on the Mach-Zehnder structure has an extinction ratio of 41.43dB, a C _L of 0-2.6mg/mL, and a sensitivity of 2.67 mW/(mg/mL).

The specific response diagram of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 9. The intensity response of the sensor to three different solutions (PBS, NaCl and glucose) was compared. The maximum output light power response change of the polymer glucose sensor based on the Mach-Zehnder structure to glucose was 6.95mW, and the maximum output light power response to PBS and NaCl was 6.95mW. The output light power response changes were 0.16mW and 0.11mW respectively. The results show that the GOD on sensing arm 7 can specifically recognize glucose. Therefore, the polymer glucose sensor based on the Mach-Zehnder structure has good selectivity for glucose.

The stability response diagram of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 10. Stability is another important performance indicator of polymer glucose sensors and an important indicator of the accuracy of measurement results. The stability of the polymer glucose sensor can be expressed as: repeated measurements of the output light power under the same experimental environment (same concentration, temperature, pH, and volume of glucose solution) to characterize the fluctuation of the measured output light power. Therefore, the relative standard deviation can be used to measure the stability of the polymer glucose sensor based on the Mach-Zehnder structure. The measurements of glucose solutions with concentrations of 1 mg/mL and 2 mg/mL were repeated 10 times, and the measurement results were recorded every 5 minutes. The measured output light power fluctuation curve with time is shown in Figure 10. The experimental results show that although the sensor measurement The output optical power fluctuates to varying degrees with time, but it also fluctuates within a very small range. The relative standard deviation of the single-point concentration measurement is about 2×10 ^-3 . Therefore, the polymer glucose based on the Mach-Zehnder structure of the present invention The sensor has good stability in measuring the concentration of glucose solution.

The durability response diagram of the polymer glucose sensor based on the Mach-Zehnder structure in this embodiment is shown in Figure 11. Durability means that the light intensity response to glucose solutions of different concentrations can maintain good consistency and accuracy. Excellent durability is a necessary prerequisite for long-term use of the sensor. The response test of the polymer glucose sensor after being stored at room temperature for different times was carried out. The specific experimental operations were as follows: After the same polymer glucose sensor was stored at room temperature for 15 days and 40 days respectively, it was tested using glucose solutions of different concentrations. Measurement, the optical output characteristic curves under different glucose concentrations at different times are shown in (a) in Figure 11. After 15 days and 40 days, they show a consistent change trend with the initial measurement results. As the concentration continues to increase, the output optical power obviously increases. Moving in the decreasing direction, the change rates after 15 days and 40 days are 2.2% and 3.2% respectively. At the same time, the two main performance parameters of sensitivity and loss were also examined. It can be seen that after 15 days and 40 days, the measurement results are shown in (b) in Figure 11. The loss of the polymer glucose sensor based on the Mach-Zehnder structure There is no significant change in the sensitivity, the loss range is 2.36-2.50dB, and the sensitivity range is 2.67-2.53mW/(mg/mL). Although the response intensity, loss and sensitivity of the device after being left for a period of time are slightly reduced compared to the performance when tested immediately after processing, the glucose sensing range of the polymer glucose sensor based on the Mach-Zehnder structure does not change significantly, indicating that at room temperature The polymer glucose sensor still maintains a high degree of consistency in its response to glucose after being stored for different times.

The parts not described in the present invention are applicable to the existing technology.

Claims (7)

1. A polymer glucose sensor based on Mach-Zehnder structure, including a PDMS lower cladding layer, a PMMA core layer and a PDMS upper cladding layer from bottom to top; characterized in that the PMMA core layer includes an input waveguide, an output waveguide, 1×2 MMI coupler, 2×1 MMI coupler, curved waveguide, sensing arm and reference arm; the sensing arm and the reference arm are equal in length and parallel, and they are set symmetrically with the center line as the axis; at a temperature of 40°C GOD is fixed on the sensing arm of the PMMA core layer through an acidic coupling agent to form a three-dimensional rectangular contact structure. The upper surface of the three-dimensional rectangular contact structure is lower than the upper surface of the PDMS upper cladding layer and higher than the upper surface of the sensing arm. ; The refractive index variation range of the GOD is 1.3352-1.3400, the arm length of the sensing arm is 1740µm, and the arm spacing between the sensing arm and the reference arm is 130µm; the bending radius of the curved waveguide is 800µm, and the curved waveguide The lateral length of the curved waveguide is 430µm, and the deflection angle of the curved waveguide is 0.28rad; The loss of the polymer glucose sensor based on the Mach-Zehnder structure is controlled within 1.6dB, and the sensitivity is 2.67 mW/(mg/mL). 2. The polymer glucose sensor based on Mach-Zehnder structure as claimed in claim 1, characterized in that the polymer glucose sensor based on Mach-Zehnder structure has a loss of 1.58dB and an extinction ratio of 41.43dB. 3. The polymer glucose sensor based on Mach-Zehnder structure as claimed in claim 1, characterized in that when the input optical power is 10mW and the glucose solution concentration is 0mg/mL, the maximum output optical power is 6.95mW, and when When the glucose solution concentration is 2.6mg/mL, the minimum output light power is 0.0005mW. The sensor achieves a linear response to the glucose concentration in the range of 0-2.6mg/mL, and the glucose concentration sensing range is 0-2.6mg/mL. 4. The polymer glucose sensor based on Mach-Zehnder structure as claimed in claim 1, wherein the relative standard deviation of the polymer glucose sensor based on Mach-Zehnder structure is (1.5-2.5)×10 ^-3 , the lowest detection limit is 0.1mg/mL. 5. The polymer glucose sensor based on Mach-Zehnder structure as claimed in claim 1, characterized in that the thickness of the PDMS lower cladding layer and the PDMS upper cladding layer are both 10 μm, and the refractive index is 1.4040; the PMMA core layer The thickness is 1µm and the refractive index is 1.4880; the distance from the upper surface of the sensing arm to the upper surface of the three-dimensional rectangular contact structure is 2-3µm. 6. The polymer glucose sensor based on Mach-Zehnder structure according to claim 1, wherein the waveguide width of the curved waveguide is 1.5 μm and the height is 1 μm. 7. The polymer glucose sensor based on the Mach-Zehnder structure as claimed in claim 1, wherein the GOD solution is obtained by dissolving GOD powder in a PBS buffer with a pH of 5.5 to form a mass concentration of 30 mg. /mL GOD solution; The GOD solution is dropped on the sensing arm of the PMMA core layer and solidified to form a three-dimensional rectangular contact structure on the sensing arm.