Non-invasive glucose measurements in mice using mid-infrared emission spectroscopy

Background: In this article we present the design, construction and the first field tests of a new non-invasive blood glucose analyzer for mice using infrared radiation (IR) from a mouse tail. Thermal radiation from the blood vessels passes through a temperature gradient between the inner body and the ambient temperature outside. Method: The temperature gradient Causes an effective radiography of the colder skin layers resulting in an absorption spectrum of the fingerprint region in the infrared between 9 and 10 mu m and thus allows estimation of glucose concentration. The realization of these measurements required an optical geometry designed for optimal detection of the tail radiation. The implementation of signal modulation and lock-in detection reduces the noise of the measurement. Results and conclusion: The analyzer delivers a signal proportional to glucose concentration. Continuous glucose measurements were done and compared to an implanted glucose sensor. The glucose concentrations and time-dependent changes in both methods are similar, validating the concept for the non-invasive blood glucose analyzer described in this paper. (C) 2009 Elsevier B.V. All rights reserved.