In this paper, to find the quantitative errors of aqueous glucose induced by the temperature change at every wave point
ranging from 1200 to 1700 nm, the calibration curve is calculated and shown. During the measurement the temperature
varies from 30°C to 40°C, at a 2°C interval, and aqueous glucose concentration ranges from 100 mg/dL to 500 mg/dL, at
a interval of 100 mg/dL. The absorption of aqueous glucose decreases with the increasing of temperature, also the
absorbance decreases. In addition, only 1°C change in the temperature induces about -7xlO-3and -4x10-3 errors in the
absorbance of the aqueous glucose at the wavelength of 1550 and 1610 nm respectively. To decrease or even eliminate
the error caused by the temperature, two methods are put up in this paper.
KEYWORDS: Glucose, Photons, Absorption, Scattering, Diffuse reflectance spectroscopy, Blood, Monte Carlo methods, Tissue optics, Near infrared spectroscopy, Near infrared
Non-invasive glucose monitoring with optical methods has obtained increasing interest, in that the methods have shown great benefit for diabetes. Nevertheless, low sensitivity and signal to noise ratio (ratio of effective photons) are two major difficulties in non-invasively NIR spectral monitoring of blood glucose concentration. Designing the optical probe properly is one of the effective ways to improve measuring sensitivity and ratio of effective photons. In this paper, definition about ratio of effective photons in measurement of glucose is introduced. And then effect of glucose on optical properties of human skin is analyzed, based on this, two kind of sensitivities for diffuse reflectance, namely sensitivity to absorption and that to scattering, is derived. To investigate the ratio of effective photons and sensitivities, Monte Carlo simulations have been performed on a three-layered media with optical parameters similar to those of human skin. The results have shown that (1) high ratio of effective photons, even as high as 60%, can be obtained by choosing proper the separation between source and detector; (2) sensitivity of diffuse reflectance to absorption and scattering has different dependence on source-detector separation, which enables one can have different options by making use of different effect from glucose level changing. In the end, some suggestions have been put forward to improve precision of measurement of blood glucose.
Concept of penetration depth of diffused photons migrating in turbid medium is introduced, and subsequently, distribution of penetration depth and mean penetration depth in three-layered media are investigated by using of Monte Carlo simulation technique. An optimal source-detector separation is derived from the mean penetration depth referring to monitoring the change of chromophore concentration of the sandwiched layer. In order to verify the separation, we perform Monte Carlo simulations 80 times with varied absorption coefficient of the sandwiched layer. All these diffuse reflectance of 80 times of Monte Carlo simulations are used to construct a calibration model with the method of PLS. High correlation coefficients and low RMSEP at the optimal separation have conformed correctness of the selection.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.