Exploration And Researches Of Non-invasive Blood Glucose Measurement Method Of Differential Spectroscopy Based On Blood Volume Difference

Non-invasive and continuous blood glucose monitoring by optical method playsan important role in diagnosis and treatment for diabetes patients. Non-invasive bloodglucose measurement is always a scientific research challenge, the main difficulty liesin the fact that glucose’s optical information is weak and measurement backgroundgreatly changes. To eliminate influences of measuring background on blood glucosemeasurement, several non-invasive blood glucose reference measurement methodshave been developed in recent years, and two reference measurement methods ofdifferential spectroscopy based on blood volume changing have been researched inthis article, the main research work includes:Due to the theory of differential spectroscopy measurement based on bloodvolume difference uses pulse information generated by blood circulation inNear-infrared(NIR) spectroscopy measurement, therefore, the intensity of pulseinformation is investigated first, and the influence of pulse information on bloodglucose measurement is revealed. Meanwhile, a strategy for selecting blood glucosemeasurement part according to pulse signal intensity is proposed for differentmeasurement methods. Since skin temperature can reflect pulse information indirectly,intensity information of skin surface temperature changes is effectively extracted byinfrared image sequences using wavelet transform and power spectrum analysis,information from finger, palm, and wrist is compared and found that amplitudechanges of finger is largest, palm is least, and wrist is in the middle; larger area ofpalm is analyzed and two dimensional scatter diagram of temperature amplitudechanges is acquired; finally, NIR spectroscopy acquisition experiment is conducted onthese three measuring parts, after comparison, viability of measurement part selectionmethod is verified.Furthermore, four possible measurement ways are proposed for two referencemeasurement methods, namely differential spectroscopy based on natural pulse anddifferential spectroscopy based on vascular occlusion, each measurement principleand characteristic is explained. Sources of random errors and influence factors areemphatically analyzed, and on this basis, achievable measurement accuracy of fourdifferential spectroscopy methods is evaluated, the results indicate that: 1) The concentration resolutions of four methods have great differences whenonly apparatus’s thermal noise is considered and under highest Signal toNoise Ratio (SNR) level. Differential NIR spectroscopy based on vascularocclusion spectrometry is closest to clinical test target, which is on10~30mg/dL level.2) Random noise induced by testing interface changes is actually measured byfour measurement ways, concentration resolutions at that time are acquired.The results show these four measurement ways do not meet the requirement.3) SNR of measuring signal is back stepped if the requirement that measurementaccuracy is below9mg/dL is satisfied, which has2or3orders of magnitudegap with actual measurement SNR.Finally, blood glucose measurement method based on two-wavelengthdifferential spectroscopy is proposed and a theoretical mathematical model of thismethod is built. Spectral data in vascular occlusion spectrometry is actually correctedand concentration resolution is greatly reduced. In order to validate its feasibility,OGTT test is conducted, offering reference for following development of differentialspectroscopy.Above all, two non-invasive blood glucose differential measurementspectroscopy methods based on blood volume changing have been researched in thisarticle, achievable accuracy levels at the present stage of four possible measurementways are evaluated, providing evidence for choosing blood glucose measurementmethods. Meanwhile, the feasibility of blood glucose measurement method based ontwo-wavelength differential spectroscopy is validated preliminarily in this article.