Design Of Wireless Tear Glucose Detection System Based On Electrochemical Sensor

With the acceleration of the aging process,diabetes has gradually become the most common chronic disease which has high incidence rate,serious complications and cannot be completely cured.This has aroused great attention from all walks of life.It is particularly important to monitor glucose concentration in blood and even body fluid of diabetic patients in time.Tear glucose detection is not only a non-invasive detection,but also expected to be integrated into the flexible wearable contact lens system in the future to realize the real-time detection.Therefore,it has important research value and certain medical application prospects.According to the characteristics of low concentration and small fluctuation of tear glucose,a wireless power supply tear glucose detection system was designed based on electrochemical sensor with high detection accuracy and sensitivity.Following works had been done in this paper:Firstly,a wireless tear glucose detection system based on electrochemical sensor was proposed.According to the demand of three electrode electrochemical sensor,the sensor readout circuit including the constant potential and signal amplification module was designed and manufactured.The circuit can provide 0.7V constant potential for the electrochemical sensor and amplify n A～μA level current.Data communication module was also designed which realized data communication function.Secondly,wireless power supply scheme for sensor readout circuit using microwave power transmission module was proposed.HFSS software was used to simulate and optimize the loop receiving antenna with central frequency of 2.4GHz which was suitable for eye sensing.On this basis,the fabrication technique of ink-jet printing antenna was studied and the optimal preparation conditions of ink-jet printing antenna were determined.According to the antenna prepared by different processes,the vector network analyzer was used to test.The center frequency of the ink-jet printing antenna is 2.38GHz,which is closest to the simulation result of 2.4GHz.The results show that the flexible antenna prepared by ink-jet printing had the highest receiving power under the same conditions.Finally,the filter and rectifier matching circuit were designed.The circuit was simulated and optimized by ADS software.The output voltage of the circuit was improved and the rectifier efficiency of the circuit reached 35.14%.According to the test of the system,the results are as follows:the system can receive power and get stable 2.5V output voltage after rectification at the distance of 3cm which can meet the power supply demand of the sensor readout circuit.The system can detect the concentration of tear glucose in the range of 0～0.8m M,the detection limit is 38μM and sensitivity is12.55μA·mm^-2·m M^-1.The wireless tear glucose detection system designed in this paper has high sensitivity and detection accuracy.The system also has strong anti-interference to other substances in tears and has compatibility to different electrodes.