An in Vivo Acquisition Device for Near Infrared Blood Spectra

The near infrared spectroscopy for the noninvasive determination of blood compositions has attracted significant interest in recent years. Lately the Dynamic Spectroscopy (DS), a new device for artery blood compositions detecting is introduced. It can eliminate the interferences of individual discrepancy and measurement conditions. But acquisition of the spectrum meeting the accuracy of blood compositions analysis is a bottleneck to be resolved. In this article, a new acquisition device of dynamic spectrum is present. On the hardware side, logarithmic amplifier is used to convert the photoelectric pulse wave to the logarithmic pulse wave. This modification compresses the dynamic range of the system and reduced the cost of the signal picking device. On the software side, based on the fast Fourier Transform (FFT) algorithm, the calculating of the peak to peak value of the photoelectric pulse wave in the time domain is converted to the extracting of the fundamental components of the logarithmic pulse wave. Due to the plus function of FFT to the signal to noise ratio (SNR), the resolution of the spectrum analysis is improved.