High-Resolution Tilt Sensor Based on Stripe-Shaped GaN Optoelectronics

Technological advancement has driven a significant rise in the demand for compact sensing devices capable of detecting slight angle changes. This work introduces an optical tilt sensor for high-resolution tilt measurement. The GaN-on-sapphire device, with dimensions of $6\times 1.5\times 0.12$ mm2, comprises a light-emitting diode (LED) and a photodetector (PD) monolithically integrated within a single chip. The stripe-shaped device is flip-chip mounted on a printed circuit board and enclosed in an acrylic container with a size of $51\times 10\times 10$ mm3, filled with silicone oil. The oil acts as a liquid pendulum, modulating the light that reaches the detector when the sensor is tilted. The experimental evaluation reveals that the GaN tilt sensor exhibits a linear response and a sensitivity of $10.2~\mu $ A/° within ±6°, achieving a high resolution of 0.0006° and fast response/recovery times of 85/83 ms. A control circuit incorporating a programmable microprocessor is implemented for wireless data transmission. These attractive attributes render the developed sensor a promising option for various high-resolution, real-time tilt sensing needs, and its potential for angle monitoring in different practical applications is demonstrated.