A Late-Model Optical Biochemical Sensor Based on OTS for Methane Gas and Glucose Solution Concentration Detection

The traditional sensor structures are usually designed for single-function detection, but a dual-function optical biochemical sensor that can simultaneously detect methane (CH
₄
) gas and glucose solution concentrationvia the change of refractive index (RI) is proposedin this paper,which is suitable for multiple application scenarios. Two kinds of cavities with different thicknesses are developed for gas and liquid measurement respectively. The sensitive and narrow absorption peak benefits from the optical Tamm state (OTS) based on the metal properties, which provides the basis for high-precision detection. By coating the CH
₄
-sensitive membrane, the qualitativea nd quantitative analysis of CH
₄
concentration
$C_{CH4}$
of 0–3% (RI of 1.4364–1.4478) can be accurately realized. The sensitivity (S) is 7.89 THz/RIU, the figure of merit (FOM) is up to 1315, the quality (Q) value is 88832, and the lower detection limit (DL) is about 3.8
$\times$

$10^{-5}$
. If such a sensor is used to detect the concentration of glucose aqueous solution (
$C_{G}$
) of 140–330 g/L (RI of 1.3489–1.3715), the corresponding values are 2.55 THz/RIU, 319, 66601, and 1.5
$\times$

$10^{-4}$
, which can provide the possibility for the biomedicine blood glucose detection. In addition, the effects of different metal layer thicknesses on sensor performance are discussed briefly.