Bend a diamond membrane about 5 micrometres thick, and it generates roughly 70 millivolts at just 1.4% bending strain, a voltage coefficient of 82.2 millivolts-meters per newton, according to a study published March 18, 2026, in Science Advances.
That number matters because it beats established piezoelectric materials like barium titanate, a benchmark researchers didn’t expect a diamond to touch.
For more than 100 years, textbooks classified diamond as strictly non-piezoelectric, since generating an electrical charge under mechanical stress requires a material that can bend and deform, not exactly diamond’s reputation.
Researchers led by Professor Zhiqin Chu and Professor Yuan Lin at the University of Hong Kong decided to test that assumption on a version of diamond thin enough to actually flex.
The scientists used microwave plasma chemical vapour deposition to grow diamond membranes layer-by-layer on a silicon substrate and then detached the one-micron-thick, two-inch-wide membrane through edge-exposed exfoliation using sticky tape in what is said to have taken around 10 seconds.
The scientists attached the membrane to a flexible polyethylene terephthalate substrate and fixed it on one side while subjecting it to pressure from the other end to detect any voltage generated due to its bending.
They found that any voltage detected was not influenced by rubbing and environmental factors and attributed it to asymmetrical grain boundaries in the membrane, which result in charge polarisation between the upper and lower parts of the material.
More importantly, the effect disappears completely in the case of a single-crystal diamond since it is the imperfections at these boundaries that cause this phenomenon to happen.
The maximum piezoelectric response was observed in diamond films with thicknesses close to 5 micrometres, and this was attributed to the grain-boundary asymmetry changes as the diamond grows.
