Optical Magnetic Field Microsensors Based on GaN Diode Optopairs Integrated With Magnetic Fluids

In this work, the development of optical magnetic microsensors based on chip-scale GaN-on-sapphire diode optopairs integrated with magnetic fluids is demonstrated. The submillimeter-sized optopairs function as light emitters and detectors and the transparent sapphire substrate as light-guiding media is covered with magnetic fluids using PDMS recesses. The magnetic fluid strength introduces the optical reflection introduces changes in optical reflection at the boundary between the sapphire and the magnetic fluid, thus varying the amount of light received by the photodetector. Verified through experimental measurements, the micro-sensor exhibits a wide detection range of 50-2000 Gs and a fast response time of 0.06 s. The developed magnetic sensor provides remarkable features of rapid response, wide measurement range, high compactness, and simplicity of operation, making it well-suited for use in practical applications.