The safe and efficient transmission of electricity relies on the reliable operation of high-voltage cable systems. Partial discharge (PD) in cables often leads to insulation degradation; therefore, accurate detection of PD is crucial to ensuring the safe and stable operation of power equipment.

Traditional electromagnetic signal detection methods for PD measurement are prone to interference and struggle with accurate detection. To address this, professors Zhong Lisheng and Gao Jinghui from the School of Electrical Engineering at Xi'an Jiaotong University (XJTU) developed flexible acoustic sensors.

These devices possess inherent anti-electromagnetic interference properties and conformability to curved surfaces, making them an essential tool for precise PD sensing in cables.

However, a contradiction exists in flexible piezoelectric thin-film acoustic sensing materials between enhancing the piezoelectric coefficient and reducing the dielectric constant. This contradiction limited the piezoelectric voltage coefficient to the range of 20-40 mV•m•N⁻¹, consequently restricting sensing accuracy.

To overcome this bottleneck, the team proposed a buffer layer-mediated strategy to enhance the performance of flexible piezoelectric thin films. This involves introducing a TiO2 buffer layer beneath the Pb(Zr0.52Ti0.48)O3 (PZT) thin film.

On the one hand, the low dielectric constant of the buffer layer reduces the equivalent dielectric constant of the composite film. On the other hand, the buffer layer promotes PZT grain refinement, enhances preferential orientation, and induces self-polarization, increasing the piezoelectric coefficient of the PZT thin film and leading to a substantial improvement in the sensing performance of the flexible piezoelectric material.

This approach resulted in flexible piezoelectric thin films with a piezoelectric voltage coefficient as high as 124 mV•m•N⁻¹. The developed flexible ultrasonic sensor provides a novel sensing solution for the acoustic detection of PD in cables.

The research findings, Enhancing Sensitivity of Flexible Piezoelectric Thin-Film Acoustic Sensors via Buffer Layer Engineering for Insulation Health Monitoring of Power Cables, were published in the top international journal Advanced Functional Materials.