Research on the best measurement situation between optical probe and tissue surfaces in non-invasive detection

Near-infrared spectroscopy is often used for the non-invasive detection of composition in the human body, such as that of blood glucose and haemoglobin, due to its high penetration depth intotissues. Although it is feasible to position the optical probe precisely, contact situation between probe and humantissues is a difficult problem to determine because of physiological tremor and mechanical performance of bio-softtissue. Here, we proposed a novel estimation method for the situation between the optical probe andtissue surfaces based on the dynamic auto-correlation matrix of two-dimensional correlation spectroscopy (2DCOS) andradar chart. The diffuse reflectancespectra from the left palm of 4 healthy volunteers were collected while the optical probe gradually approached and pressed bio-tissues with a custom-design controlling device. 2DCOS in the wavelength with lower absorption (1000-1400 nm) was calculated under the perturbation of relative-distance and contact pressure between the optical probe andtissue surface. The synchronous 2DCOS showed that the surface reflection and diffuse reflectance were greatly affected by the contact conditions in 1100 nm, 1220 nm, and 1300 nm. Then the dynamic auto-correlation matrix of 2DCOS was established for the adjacentspectra, and the significant difference wavelengths were used to buildradar charts to determine the critical contact situation visually. Results showed that the maximum variations of dynamic auto-correlation matrix appeare...

Source: Review of Scientific Instruments - November 21, 2016 Category: Physics Authors: Xuyao Yu, Rong Liu, Hui Yu, Jiao Wang, Jun Wang and Kexin Xu Source Type: research