All-Digital 1550 nm Optical Aqueous Glucose Solution Measurement System

摘要

An all-digital 1550 nm optical measurement system is proposed for measuring the concentration of aqueous solutions of glucose to investigate the feasibility of NIR blood glucose measurements. A microcontroller was used to generate the excitation signal for a 1550 nm laser module as well as generate the reference signal to perform the lock-in amplifier function. A sine wave was generated inside the firmware to drive the laser module through a current DAC. The reference signal was generated by reading the monitor diode inside the laser module through the microcontroller’s internal ADC. A cooled photodetector was used to measure the light level where its output was digitized by a 24-bit ADC after analog signal conditioning. The glucose concentration result for the measurement was calculated performing DSP functions using the mentioned signals as set out in this paper. A correlation was successfully observed between measured signal level and glucose concentration.