Researchers in South Korea and the UK have produced a film that makes electricity when you bend it - and crucially it is over a million times better at this than other crystalline solids with the same properties. Their approach makes it possible to control the strength of permanent electric fields in designer films, which is required for devices like photovoltaics. Piezoelectric materials generate electric fields when pressed or pulled. In contrast, flexoelectric materials produce these fields when bent - they react to variation in strain across the material, rather than strain itself. But because solids are typically difficult to bend,...