A Century-Old Belief About Diamond Has Just Been Overturned

Researchers have uncovered an unexpected electrical response in ultrathin diamond membranes, challenging a century-old assumption about the material.

Diamond is renowned for resisting pressure, heat, chemicals, and wear. But researchers have now shown that, when made thin enough, it can also generate electricity when bent. An ultrathin diamond membrane produced stable voltage signals under mechanical strain, overturning the long-standing assumption that diamond is fundamentally non-piezoelectric.

The work was led by Professor Zhiqin Chu of the Department of Electrical and Computer Engineering and Professor Yuan Lin of the Department of Mechanical Engineering at the University of Hong Kong (HKU).

For more than a century, diamond was excluded from the class of materials that convert mechanical deformation into electrical charge. Its exceptional hardness, strength, thermal conductivity, chemical stability, acoustic velocity, dielectric breakdown strength, and ultrawide bandgap made it valuable in advanced devices, but usually only as a durable structural platform for separate piezoelectric layers in microelectromechanical systems (MEMS). As a result, the idea of generating electricity directly from diamond was widely considered unrealistic.

Diamond Membrane Piezoelectricity and Deflection Tests — Ultrathin polycrystalline diamond membranes respond to charged objects. Credit: The University of Hong Kong

Flexible membranes make diamond responsive

Using a recently developed edge-exfoliation method, the HKU researchers created an ultrathin and flexible polycrystalline diamond membrane. Making the material this thin allowed normally rigid diamond to bend substantially, and that deformation consistently produced measurable voltage signals.

To ensure the signals did not come from environmental interference or triboelectric artifacts caused by contact and friction, the researchers repeatedly bent the membrane under several controlled conditions. The stable and reproducible electrical output confirmed that the diamond membrane displayed a piezoelectric response.

Zhiqin Chu and Yuan Lin With HKU Research Team — The interdisciplinary research team led by Professor Zhiqin Chu (second from left) and Professor Yuan Lin (third from the left). Credit: The University of Hong Kong

Grain boundaries generate the voltage

First-principles calculations traced the effect mainly to asymmetrical grain boundaries, the interfaces where individual diamond crystals meet within the membrane. As bending increased, electrical charge accumulated along these boundaries, producing a voltage difference between the membrane’s upper and lower surfaces.

Diamond is biocompatible, chemically stable, and nontoxic, making the effect potentially useful in medical and energy technologies. Future implantable devices, for example, could use piezoelectric diamond membranes as deformation sensors or as power sources that generate their own electricity.

The findings expand diamond’s possible uses beyond its traditional role as a mechanical support material. They could also inform the development of reliable miniature energy systems and sensing devices that operate without an external power supply.

Reference: “Uncovering piezoelectric effect in polycrystalline diamond membranes” by Jixiang Jing, Bicong Wang, Yumeng Luo, Yicheng Wang, Zhongqiang Wang, Yiyao Liu, Dong-Keun Ki, Xinghua Shi, Qi Wang, Kwai Hei Li, Yuan Lin and Zhiqin Chu, 18 March 2026, Science Advances.
DOI: 10.1126/sciadv.aea8318

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