Research On Portable Biochemical Sensor High Precision Detection Technology And System Implementation

Biochemical sensors are important front-end sensing elements for biological and chemical detection,which are mainly used in environmental pollution monitoring,biomedical detection,and scientific research and industrial and agricultural production.Light Addressable Potentiometric Sensor(LAPS)is a semiconductor-based biochemical sensor.Compared with other similar sensors,LAPS has many advantages,such as simple structure,high accuracy,fast response speed and light addressing,which makes researchers here and abroad have carried out many studies on LAPS in biological,chemical and other fields.But due to the environmental noise interference,semiconductor lattice defects,light modulated signal fluctuations and other reasons,the LAPS detection accuracy and signal to noise ratio(SNR)are affected.Therefore,this paper focuses on improving the LAPS detection accuracy and SNR,proposes a high-precision detection technique based on orthogonal phase detection.On the other hand,the current LAPS detection system needs to be improved in miniaturization and integration.For this purpose,a portable biochemical sensing circuit system is designed to provide a scheme for the future application of LAPS detection system in clinical and home life.The main studies of this paper mainly include the following aspects:1.For overcoming the LAPS detection lack of precision,a technique based on orthogonal phase detection method for LAPS detection is proposed.In this method,the phase information of the output signal can be obtained by the LAPS output signal multiplying with two orthogonal signals,through the low-pass filter dividing the DC component.The method of realizing the detection technology by Lab VIEW software and PCB hardware circuit is introduced respectively.2.To verify the correctness of the application of orthogonal phase detection technology in the field of LAPS detection,and to compare the conventional detection method with the phase detection method,a LAPS detection system with Lab VIEW as the data processing platform and data acquisition card as the core is built.The realization method of the detection system is introduced in detail,and under this detection system,the influence,the sensitivity,the linearity,the SNR,and the light intensity of the modulated light signal on the amplitude detection method and the phase detection method are compared and analyzed,and the selection recognition of LAPS is verified.3.To realize the integration of LAPS detection system in sensing,detection,and display parts and to solve the problems faced by LAPS detection system in miniaturization,a portable biochemical sensing circuit system with FPGA and ARM as the core is designed.First,the overall design scheme of the detection system is introduced,then the hardware implementation of the key modules in the portable biochemical sensing system is described in detail,and the software implementation method of the portable biochemical sensing circuit system is given.Under the system,the spatial concentration distribution of the measured substances at 256 points on the area of 4 cm×4 cm of the LAPS was completed.And the sensitivity and precision of LAPS detection are improved by the above research.The experimental results show that the detection method based on orthogonal phase detection technology improves the sensitivity of the traditional detection method by 7 m V/p H,the accuracy increases by 14.9 mp H,the SNR increases by 8.2827 d B.A portable biochemical sensing circuit system designed in this paper is of great significance for the study of miniaturization of LAPS detection system.