Researchers at the University of Hong Kong have discovered that ultrathin, flexible diamond membranes can generate electricity when mechanically deformed, a finding that contradicts a long-held scientific assumption. The discovery, led by Professor Zhiqin Chu and Professor Yuan Lin, could pave the way for diamond-powered sensors, energy systems, and medical implants.
For over a century, diamond has been considered a non-piezoelectric material – meaning it was not expected to produce an electrical voltage when bent or stressed. This understanding has limited its use in microelectromechanical systems (MEMS), where it typically serves as a structural component for other piezoelectric materials. The notion of generating electricity *from* diamonds was therefore considered impractical.
The HKU team overcame this limitation by creating ultrathin, flexible polycrystalline diamond membranes using a recently developed edge exfoliation method. This process allowed the normally rigid diamond to bend significantly. When the researchers flexed the membrane, they observed consistent and repeatable voltage signals. Extensive mechanical cycling experiments were conducted to verify the results and eliminate potential interference from environmental factors or triboelectric effects.
Detailed first-principles calculations revealed that asymmetry at the grain boundaries within the polycrystalline diamond membrane is responsible for the electrical effect. These boundaries separate the tiny diamond crystals that comprise the material, and their behavior under bending creates electrical charge polarization.
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