Rapid, Sensitive and Selective Optical Glucose Sensing with Stimulated Raman Scattering (SRS)

Abstract

Optical blood glucose sensing offers pain-free, non-invasive, continuous monitoring with minimum risk of infection since it does not require breaking the skin barrier. Among various optical detection and spectroscopic techniques, only Raman scattering offers both high-accuracy and chemical-specific acquisition along with label-free sensing. However, spontaneous Raman scattering is a feeble process. The integration time is long and high laser intensities are demanded to achieve acceptable sensitivity in detecting physiologically relevant glucose levels. This hinders the inherent advantages of Raman scattering-based technologies as a wearable medical point-of-care device. Therefore, this study applies stimulated Raman scattering (SRS) to glucose sensing, which overcomes the limitations of spontaneous Raman spectroscopy. This is the first study demonstrating the application of SRS in glucose concentration monitoring. Herein, by enhancing the Raman effect using stimulating excitation, we have recorded a linear calibration curve for concentrations below 100 mol/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with a theoretical limit of detection (LOD) of 3.5 mol/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in a phenomenal 0.6 s integration time merely by employing univariate data analysis. In addition, we have assessed the optimum required averaged laser power and sensing mechanism's feasibility in complete human serum glucose measurement and established a highly selective detection mechanism by solely identifying the characteristic Raman shift peak of glucose around 1130 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> .