At the  University of Cambridge (UK), a new type of transistor has been developed which operates at extremely low levels of energy making it ideal for use in wearables and sensors that operate from batteries or even energy harvesting from secondary energy sources. In theory an AA cell contains enough energy to power a transistor for 1 billion years!
As far as I know Cambridge is not Hogwarts so there is unlikely to be any magic involved, just classical semiconductor research methods. Sungsik Lee and Arokia Nathan have published a paper outlining the results of their research at Cambridge in the renowned journal Science under the title ‘Subthreshold Schottky-barrier thin-film transistors with ultralow power and high intrinsic gain’ It describes a type of transistor based on a thin film of indium gallium tin oxide with a Schottky barrier layer operating in the deep subthreshold regime (i.e., near the OFF state) at low supply voltages (<1 volt) and ultralow power (<1 nw) with high gain (>400). By using a Schottky-barrier at the source and drain contacts, the current-voltage characteristics of the transistor are virtually channel-length independent with an infinite output resistance.

The characteristics of the thin film transistor make it ideal for use with extremely high impedance circuits, where low frequency analog signals need amplification using low energy levels. Wearables and sensors for smart devices are just two likely applications.