Design Of Data Acquisition System In Non-invasive Blood Components Analysis By Near Infrared Spectroscopy Based On FPGA

Blood component testing is an important method to diagnose disease. Routine blood component detection using blood sampling, which not only bring pain and cross infection to the patients, but also cannot immediately get result. Therefore, the “human blood components noninvasive, continuous monitoring” is for people urgently hope. Near-infrared absorption spectroscopy(NIRS) technique has a great advantage in the detection of non traumatic blood components, such as no reagents, no pollution, no trauma and continuous monitoring. However, domestic and foreign scholars in this field have spent a lot of time, still can?t make the near infrared non-invasive blood component analysis technology to achieve the level of clinical application.Main problems are: the signal of blood biochemical composition is very weak, such as glucose, cholesterol and triglyceride. More over all sorts of organizations has big influence on the near infrared spectral interference of blood. We proposed “blood volume spectral subtraction method” to eliminate human tissue background interferences, “blood volume spectral subtraction method” was proposed. However, the spectral instrument measuring system should meet the following requirements:(1) spectrum system must collect all wavelengths signal at the same time;(2) spectrometer can collect 50 amplitude spectrum per second at least;(3) the signal-to-noise ratio of spectrometer is at least 10000:1. On the basis of the early stage of the laboratory research results, the detector we use can collect 16 independent wavelengths at the same time, so it can ensure all wavelengths of light intensity signal be collect at the same time, more over insure the instrument has high acquisition speed and signal-to-noise ratio. So it requires the data acquisition system of the instrument can simultaneously collect 16 channel blood pulse wave data at a high speed and high signal-to-noise ratio.In this paper, the data acquisition system of high speed and multi-channel spectral data in non-invasive blood component analysis is studied. This paper mainly includes the hardware and software design of the data acquisition system. The main conclusions were as follows:1) This article introduced the hardware system of the high-speed multi-channel data acquisition system of near infrared non-invasive blood components analysis in detail, and the design plan is proposed. The hardware system consists of two pieces eight channels A/D chips to achieve 16 channel data acquisition; Data storage is realized by using an SRAM chips; Data communication is realized by using USB chip CY7C68013, FPGA is used as the control core of system.2) Design the FPGA logic of the high-speed multi-channel data acquisition system of near infrared non-invasive blood components analysis in detail, which contain A/D control module, ping-pong RAM control module, SRAM control module and USB data communication module, using Verilog HDL language to complete the design of the various modules, realized the 16 channel human blood pulse wave data acquisition of high speed, high signal-to-noise ratio.3) A 1.357 V voltage stabilizer were measured by the system, the spectrum data acquisition system can collect 16 channels signal parallel and fast under the sampling frequency of 19531 Hz and the repetitive signal-to-noise ratio is over 40000:1. The system can collect 305 spectrograms per second, more over it can get high SNR human body blood pulse wave signal under the same circumstances. After filtering the quantitative SNR can be up to 151.1331, the mean square error(mse) can be 5.61E-05.5) We studied the denoising method of the pulse wave signal and found the wavelet method is effective. Experiments shows that using sym8 to two layers of decomposition, the wavelet function form use the rigrsure, threshold by hard threshold can get the best filtering effect.