Researchers have uncovered an unexpected electrical response in ultrathin diamond membranes, challenging a century-old assumption about the material. An ultrathin diamond membrane produced stable voltage signals under mechanical strain, overturning the long-standing assumption that diamond is fundamentally non-piezoelectric. Flexible membranes make diamond responsiveUsing a recently developed edge-exfoliation method, the HKU researchers created an ultrathin and flexible polycrystalline diamond membrane. The stable and reproducible electrical output confirmed that the diamond membrane displayed a piezoelectric response. Future implantable devices, for example, could use piezoelectric diamond membranes as deformation sensors or as power sources that generate their own electricity.