Bracket-Diaphragm Coupled Fabry-Perot Acoustic Sensor for Partial Discharge Detection

We demonstrate a bracket-diaphragm-based Fabry-Perot (FP) cavity fabricated by two-photon 3D printing technique as a highly-sensitive acoustic sensor for the detection of partial discharge. The diaphragm consists of two parts, one is the low-frequency dominant bracket structure, while the other features a high-frequency dominant diaphragm. To achieve high acoustic sensing performance, the whole structure is optimized for mechanical mode-coupling resonance, which can significantly enhance the response to acoustic waves. The sensing performance of the device for acoustic wave detection is investigated. Furthermore, the sensor is utilized for the detection of partial discharge. Results show that the device can detect the acoustic emission waves with frequencies up to 340 kHz and exhibits well-distance responsiveness. With a minimum detectable pressure (MDP) of $3.81~\mu $ ${\mathrm {Pa/Hz}}^{\mathbf {1/2}}$ at 150 kHz, the sensor shows desirable potential for applications in partial discharge detection of electrical equipment.