Diamond has long been regarded as a material that cannot generate an electrical voltage when bent or compressed. Researchers in Hong Kong have now demonstrated that extremely thin and flexible diamond membranes can do exactly that. The discovery could eventually be used in miniature sensors, medical implants and electrical systems that harvest energy from movement.
Researchers at the University of Hong Kong have measured a clear and repeatable piezoelectric effect in polycrystalline diamond membranes. The result challenges a scientific assumption that has remained established since the beginning of the 20th century.
Piezoelectricity is the ability of a material to convert mechanical stress into an electrical voltage. When the material is bent, compressed or stretched, electrical charges inside its structure move. This creates a potential difference that can be measured between different sides of the material.
This does not mean that diamond creates energy from nothing. It converts a small amount of mechanical energy from movement into electrical energy, in much the same way as other piezoelectric materials.
The study was led by Professors Zhiqin Chu and Yuan Lin from the Faculty of Engineering at the University of Hong Kong. The findings were presented by the university and reported by ScienceDaily on 31 August 2026.
Diamond must be made extremely thin
Conventional diamond is exceptionally hard and rigid. It consists of carbon atoms arranged in a strong and highly symmetrical crystal structure. This symmetry is an important reason why diamond has not previously been considered piezoelectric.
For a piezoelectric effect to occur, positive and negative charges must be able to shift so that one side of the material develops a different electrical potential from the other. In a perfectly symmetrical diamond crystal, these charge displacements would normally cancel each other out.
Diamond has therefore mainly been used as a passive structural material in electronics and microtechnology. It is extremely hard, conducts heat effectively and withstands chemicals, strong electrical fields and demanding operating conditions.
In microelectromechanical systems, known as MEMS, diamond has, for example, served as a strong supporting structure for other materials that already possess piezoelectric properties.
The research team wanted to establish whether diamond would behave differently if it were made thin enough to bend significantly. Using a recently developed method for separating ultrathin layers, the researchers produced a flexible polycrystalline diamond membrane.
Polycrystalline means that the material does not consist of a single, perfect diamond crystal. Instead, it is made up of many extremely small crystals, or grains, joined together.
Once the membrane was sufficiently thin, the normally rigid diamond could be bent. During this process, the researchers recorded stable electrical voltage signals.
They repeated the experiments over numerous mechanical cycles to determine whether the signals would continue to appear. According to the researchers, the results were stable and reproducible.
The team also conducted tests to rule out environmental interference and the possibility of triboelectricity. A triboelectric charge can develop when two surfaces touch or rub against one another. It is the same phenomenon that can produce a static electric shock after someone walks across a carpet.
According to the researchers, these control experiments provided strong evidence that the voltage originated in the diamond membrane itself when it was bent.
Crystal boundaries create the effect
The explanation for the result appears to lie in the boundaries between the diamond’s many small crystal grains.
The researchers used advanced calculations at the atomic level to investigate what happens inside the material. Their analysis indicated that the structure at the grain boundaries does not have the same perfect symmetry as the interior of an individual diamond crystal.
When the membrane bends, electrical polarisation develops around these asymmetrical boundaries. Electrical charges are then distributed differently between the upper and lower parts of the material.
This produces a small potential difference – in other words, an electrical voltage – between the two surfaces of the membrane. The more strongly the membrane is bent, the more pronounced the displacement of charge around the grain boundaries becomes.
The fundamental crystal structure of diamond has not suddenly changed. The effect results from a combination of the material’s extreme thinness, its ability to bend and the asymmetrical boundaries between its crystal grains.
The discovery therefore does not necessarily contradict existing scientific knowledge about perfect diamond crystals. Instead, it shows that polycrystalline diamond in membrane form can acquire properties that are not present in a large, uniform diamond crystal.
This is an important distinction. Ordinary jewellery diamonds will not begin producing useful electricity when compressed or shaken. The researchers have developed a specialised technical diamond material with an exceptionally thin structure.
Could power sensors and medical implants
The findings could open new applications for synthetic diamond. The material’s main advantage is its combination of mechanical strength, chemical stability, heat resistance and electrical properties.
Diamond is also biocompatible and non-toxic, making it attractive for medical technology. A thin diamond membrane could, for example, function as a sensor capable of detecting pressure, movement or deformation inside the human body.
In the longer term, mechanical movements in the body could potentially be converted into small amounts of electricity for sensors or implants. This could reduce dependence on batteries or extend the interval between battery replacements.
Similar technology could be used in miniature self-powered industrial sensors. Vibrations from machinery, vehicles or buildings could then be converted into the electricity required to take measurements and transmit data wirelessly.
It is still far too early, however, to describe diamond as a new source of large-scale energy. The study shows that the membranes can generate an electrical voltage, but the available information does not demonstrate that they produce enough power for larger devices.
Several questions must be answered before the technology can be commercialised. Researchers need to determine how much energy can be harvested, how efficient the conversion process is and whether the membranes can be manufactured in large quantities at a reasonable cost.
Their operational lifetime must also be investigated. A material used in a sensor or medical implant may need to withstand millions or even billions of bending cycles without losing its electrical function.
The discovery should therefore primarily be viewed as a materials science breakthrough. It demonstrates that diamond does not have to remain merely a passive protective or structural material. In the right form, it can also become an active component that responds electrically to its surroundings.
Source: University of Hong Kong and ScienceDaily, published on 31 August 2026.
