Development Of Near-infrared Cerebral Tissue Blood Oxygenation Detection System Based On USB

As an important human physiological indicator, oxygen parameters of brain tissue can be used to test and evaluate human brain function and related functions. Currently the primary means to test oxygen parameters are finger pulse oxygen saturation testing, functional magnetic resonance imaging (fMRI), near-infrared spectroscopy (NIRS) techniques and so on. NIRS technology can be non-destructive, real-time, continuous monitoring of brain oxygen, overcomes the shortcomings that Other equipment is so Complex and Costly as to real-time, Continuously monitor oxygen parameters of brain tissue. So NIRS technology is widely used in brain mechanism, sports physiology, rehabilitation medicine and so on.NIRS oxygen parameter detection technology is made by Jobsis in 1977. Since then, especially since the beginning of the 20th century and 90 years, with the continuous advancement of photoelectric detection technology, signal processing techniques and computer technology, NIRS oxygen parameter detection technology has also been a rapid development. Traditional NIRS oxygen detection system uses a PCI bus card, parallel or serial (RS-232) and so on, At present, Universal Serial Bus (USB) interface for its easy installation, high-bandwidth, easy to extend the advantages is becoming the development trend of modern data transmission. Now a variety of computer peripherals devices are increasingly using USB bus data transfer, Therefore, compared to NIRS oxygen detection system with the traditional interface, the system with USB interface will be more conducive to scientific research applications.Near-infrared spectra of oxygen detection system based USB interface use two wavelengths 760nm and 850nm near-infrared light-emitting diodes, uses Op-amp integrated photodiodes OPT101 as the media converter, adopts Freescale 8-bit MCU MC68HC908SR12 as core of the data acquisition system that collects the signal measured, uploads the results to PC through the USB interface, and achieves non-destructive, real-time, continuous monitoring of human tissue oxygen parameters. The system control program is divided into two parts:host computer programs and lower computer program. Host computer program is USB drivers and applications on PC, which is responsible for establishing USB communication with the MCU, for sending control commands and receiving data, at the same time for displaying and saving data. Lower computer program is USB firmware on MCU, which is mainly responsible for the collection of near-infrared spectral data, for establishing USB communications with PC and uploading the data collected.Based on the theory of human tissue spectroscopy, the paper clarifies the theoretical methods how to obtain oxygen parameters by NIRS technology or modified Lambert-Beer law. Based on the theoretical study, the paper improves the near-infrared spectroscopy oxygen detection system software and hardware design through the combination of NIRS technology and USB interface technology. the system that uses this design has the advantages of easy installation, plug and play, which can be widely used in brain function tests and various fields through non-destructive, real-time, continuous monitoring of human tissue oxygen parameters.