Transistor could allow devices to function for months without a battery

Researchers at the University of Cambridge have developed a transistor which operates on energy ‘scavenged’ from its environment and say this could enable devices which function for months or years without a battery.

Using a principle to that of a computer in sleep mode, the transistor harnesses leakage current for its operation – the first time this has been captured and used functionally. The transistors can be produced at low temperatures and printed on materials ranging from glass and plastic to polyester and paper. The transistor is based on a geometry which uses a characteristic previously thought to be ‘non desirable’ – the point of contact between the metal and semiconducting components of a transistor, or Schottky barrier. “We’re challenging conventional perception of how a transistor should be,” said Professor Arokia Nathan of Cambridge’s Department of Engineering. “We’ve found that these Schottky barriers, which most engineers try to avoid, have the ideal characteristics for the type of ultralow power applications we’re looking at, such as wearable or implantable electronics for health monitoring.” The new design is also said to get around one of the main issues preventing the development of ultralow power transistors, namely the ability to produce them at very small sizes, while offering high gain. Operating at less than 1V and consuming less than 1nW, the transistor is said to be suited to applications where function is more important than speed. “If we were to draw energy from a typical AA battery based on this design, it would last for a billion years,” said Dr Sungsik Lee, also from the Department of Engineering.

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