Non Invasive Estimation of Blood Parameters using Fingertip Photoplethysmography

Abstract

The non invasive measurement of chromophores in blood is in great need for diagnosis of major health hazards. Frequent monitoring of blood glucose levels, along newlinewith blood urea will allow early detection of diabetes, liver dysfunction and renal diseases and monitoring the treatment in clinical settings. Hyperglycemia has newlinealso been found to be associated with chronic auto immune diseases like Lupus, newlineTakayasu Artherities. The non invasive instrument used for accomplishing these newlinetasks must meet several criteria like, accuracy and precision of the measurement. newlineMany efforts have been made by many research groups all over the world in making the procedure as much less invasive as possible by trying to reduce the blood newlinedrawn for test to microliters or by reducing the cross sectional area of the suction newlineneedle. The device should be portable, low-cost and reliable overtime. There are newlinemany modes of diagnosis that satisfy these criteria but most of them are still in a newlinedevelopmental stage. newlineAlthough many methods have been proposed and are available in literature, near newlineinfrared (NIR) spectroscopy has the advantage of meeting these rigorous demands. newlineInitially, based on the intrinsic property of the analyte molecule, the NIR spectroscopy has been carried out and the wavelength of peak absorption has been newlineidentified. Using the identified wavelength a finger clip comprising of sensor and newlinedetector has been developed for collecting the in vivo PPG (photoplethsymograph) newlinesignals. These non invasive signals are used for estimating the concentration of newlinespecific blood analyte. newlineVarious statistical techniques have been used for carrying out the calibration of newlinethe in vivo signals obtained from the photoplethsymograph based sensing circuit. newlineSecondly, these signals are calibrated using artificial neural networks to predict newlinethe analyte concentration. As typical blood analytes, blood glucose and urea are newlineused to establish the proposed methodology to noninvasively estimate the blood newlineparameters. Altogether 282 patients were available for measurem