Research On Weak Signal Detection Technology Of MEMS Glucose Sensor

When the human bodies’ insulin secretion is insufficient or insulin does notwork, blood glucose concentration will deviate from the normal level and lead todiabetes and its complications. Glucose concentration detection is the premise ofscientific diagnosis of diabetes. Based on the functional requirements of MEMSsensors used for glucose detection and interstitial fluid extraction with ultrafiltration,the micro-current detection technology of MEMS three-electrode glucose sensor isstudied and the detection and control circuits of sensor are developed. This papermainly studies the detection principle, designs and analyzes the circuits, tests theperformance of the circurts and uses the detection and control system to testglucose.Firstly, on the basis of analysis the detection principle of MEMS glucose sensor,the circurts (including constant-potential circuit and signal generating circuit) thatused to assist sensor in generating current are designed and the range ofmicro-current values is tested. By analyzing the electrochemical noise caused duringthe sensor working, denoising methods are proposed which lay a firm foundation fordesigning the micro-current detection circuits.Then, according to the characteristics of micro-current and the needs ofultrafiltration extracting motion control, the detection and control system isdesigned which consists of three major components: micro-current detection system,human-computer interaction and wireless communication and power-supply system.In order to validate the correctness of the designed circuits, the performance ofconstant potential circuit and I/V conversion circuit are analyzed using the Multisimsoftware. Besides, the source of noise in micro-current detection circuits is analyzedand the associated noise and its impact to the currents detection system arecalculated and analyzed. By arranging components and wiring and eliminating theleakage of electricity, noise immunity of the circuits is enhanced.On the basis of manufacturing the circuits board, the test system is built up andthe performance of static and dynamic characteristics of the circuits is tests. Staticcharacteristics include micro-current detection accuracy, reproducibility, sensitivity,resolution, stability and zero drift. Dynamic characteristics include the voltagefollowing characteristics of constant potential circuit, step and frequency responseof detection circuits. The test results show that the performance of detection systemmeets the design requirements.Finally, in order to test the glucose levels, the micro-current detection andcontrol circuits are integrated with MEMS glucose sensor and the response and repeatability of glucose concentration are tested. By processing the experiment datas,the glucose concentration prediction model is built up. Subsequent tests results showthat the results obtained by prediction model meet the clinical accuracyrequirements.