Highly sensitive temperature sensor using one-dimensional Bragg Reflector for biomedicalapplications.

Abstract

A theoretical investigation of multi-layer Bragg Reflector (BR) structure to design highly sensitive temperature sensor is proposed to measure the temperature over a wide range. Characteristic-Matrix (CM) mathematical tool isused to design and analyse the proposed temperature sensor. A 1D Distributed Bragg Reflector multi-layer structure is used to design and analyse the sensing characteristics of the proposed sensor. Periodic modulation in the Refractive-Index (RI) of the two materials, high and low, forms DBR multi-layer structure. Germanium and air are used as the two alternate materials of BR for high and low dielectric layers respectively. Parameters of many semiconductor materials, including germanium, varies with temperature. Here we have considered RI variation of germanium with the temperature to model and design theproposed sensor. A defect layer is introduced at the center ofmulti-layer structure to obtain theresonating modeforanincident electromagnetic wave. The sensor candetecttemperature over a wide range from100 to 550K. Aresonating mode, shifting towards different wavelength region is observed for the temperature variations. The influence of increase in the DBR layers (N)and defect cavity geometrical length (lD) is studied. The obtained results conclude that the cavity defect length and BR layers affectsthe sensing parameters of the designed sensor. The obtained RI sensitivity, Q-factor, temperature sensitivity anddetection limit of the sensor are 2.323μm/RIU, 115,000, 1.18nm/K and 9.024×10-6 RIU respectively. Theoretically obtained transmission spectrum was validated using Monte Carlo simulation.