A tunable MOEMS open microring resonator for the detection of water concentration in ethanol solutions

In this work, we present a micro-opto-electromechanical system (MOEMS) designed as a tunable microring resonator with a novel open-ring configuration. The device incorporates a low-voltage rotary electrostatic actuator to mechanically tune the overlapping region of the open ring, thereby adjusting the resonant frequency and eliminating the need for costly tunable laser sources. The behaviour and performance of the structure are assessed by employing it as an ethanol purity sensor through electromechanical and optical simulations. Results demonstrate the overall feasibility of the device, highlighting its mechanical stability and its ability to detect ethanol concentration changes via shifts in the resonant frequency.