Optomechanical Holographic Sensors - COMSOL Modelling & Experimental Studies

Optomechanical sensors have the potential to address the growing requirement for highly sensitive devices for the detection of indoor air pollutants, such sensors being low cost, highly stable, accurate and with simple readouts. In this work, an optomechanical sensing platform is presented in the form of a bilayer (photopolymer/polydimethylsiloxane) cantilever sensor. The photopolymer's hydrophilic nature allows the sensor to detect variations in relative humidity (RH) although there is significant potential for functionalization to detect other airborne analytes. In addition to a static deflection mode of sensing, a holographic diffraction grating recorded in the photopolymer layer allows for a second, more accurate, optical sensing mode. COMSOL Multiphysics, was used to model the bilayer sensor response, the results being compared with the experimental results. The deflection sensing mode offers a detection limit of 1.5 % RH while the optical mode allows for detection of 0.10 % RH.