Near-infrared bulk optical properties of goat wound tissue and human serum: consequences for an implantable optical glucose sensor

Abstract

Near-infrared (NIR) spectroscopy offers a promising technological platform for continuous glucose monitoring in the human body. Moreover, these measurements could be performed in vivo with an implantable single-chip based optical sensor. However, a thin tissue layer may grow in the optical path of the sensor. As most biological tissues are highly scattering, they only allow a small fraction of the collimated light to pass, significantly reducing the light throughput. To quantify the effect of a thin tissue layer in the optical path, the bulk optical properties of serum and tissue samples grown on implanted dummy sensors were characterized using double integrating sphere and unscattered transmittance measurements. The estimated bulk optical properties were then used to calculate the light attenuation through a thin tissue layer. The combination band of glucose was found to be the better option, relative to the first overtone band, as the absorptivity of glucose molecules is higher, while the reduction in unscattered transmittance due to tissue growth is less. Additionally, as the wound tissue was found to be highly scattering, the unscattered transmittance of the tissue layer is expected to be very low. Therefore, a sensor configuration which measures the diffuse transmittance and/or reflectance instead was recommended. (a) Dummy sensor; (b) explanted dummy sensor in tissue lump; (c) removal of dummy sensor from tissue lump; and (d) 900 µm slices of tissue lump.

Complex refractive index of normal and malignant human colorectal tissue in the visible and near‐infrared

“…Such calculations are important for optimizing the therapeutic effect of light delivery to tissue (in the “forward” direction), as well as for the improvement of contrast and resolution of optical diagnostic and tomographic methods (in the “reverse” direction) . Moreover, our results directly suggest the refractive index as a marker of colorectal dysplasia and unfold the feasibility of novel endoscopic tools based on well‐established refractive index sensor technologies .…”

In Situ Exfoliation Growth Strategy Realizing Controlled Synthesis of 3D to 2D MOF Materials as High-Performance Electrochemical Biosensors

“…To further evaluate the feasibility and accuracy of PBA/MIL-53­(NiFe)/NF in practical applications, goat serum is chosen to simulate the human blood environment for real sample analysis. − According to the normal glucose level in human serum, 4.8, 5.2, and 5.7 mM concentrations of glucose are added to the goat serum samples as standard solutions. Then, PBA/MIL-53­(NiFe)/NF is applied as the working electrode to measure the glucose concentration.…”