Engineers prepare ultra-low power transistors that could operate for years without battery

A newly introduced type of transistor opens up an assortment of novel electrical applications comprising implantable or wearable devices by drastically diminishing the volume of power used. Devices based on such sort of ultralow power transistor, introduced by engineers at the University of Cambridge, could operate for months or even years without needing a battery by utilizing energy from the environment.

Based on the same principle of a computer in sleep mode, the novel transistor needs harnesses a small ‘leakage’ of electronic current, known as a close-off-state current, for its functionalities. Such leak, like water dripping from a troubling tap, is a feature of all transistors, but this is the very first time that it has been efficiently captured and utilized functionally.

The results open up novel avenues for system design for the Internet of Things wherein most of the things we interact with every day are linked to the Internet. The transistors can be generated at low temperatures and can be highlighted on almost any substance, from plastic and glass to paper and polyester. They are grounded on a specific geometry that uses a non-desirable feature, namely the point of link between the semiconducting elements and metal of a transistor, a so-known ‘Schottky barrier.’

“We challenge the traditional perception of a how a transistor must be,” says Professor Arokia Nathan of Cambridge’s Department of Engineering. “We have found that such Schottky barriers that almost engineers attempt to avoid, actually have the basic characteristics for the sort of ultra-low power applications we are considering at, like wearable or implantable electrical for health monitoring.

The novel design gets around one of the core troubles preventing the development of ultra-low power transistors, called the ability to produce them at highly small sizes. As transistors are smaller, their two electrodes begin to influence the nature of one another, and the voltages spread, implying that below a specific size, transistors fail to operate as desired. By altering the design of transistors, the Cambridge scientists were able to utilize the Schottky barriers to keep the electrodes independent from one another, so that the transistors can be reduced down to highly small geometers.

The design also claims a very high level of gain or signal boost. The operating voltage of thetransistor is less than a volt, with power consumption below a billionth of a watt. Such ultra-low power consumption makes them ideal for applications where thefunction is highly important than speed, which is the core of the Internet of Things.

“It is an ingenious transistor concept,” says Professor GehanAmaratunga, Head of the Electronics, Energy and Power Conversion Group at Cambridge’s Engineering Department. “Such sort of ultra-low power operation is a pre-essential for most of the novel ubiquitous electrical applications, where what matters functionality – in essence ‘intelligence’ without the need for speed. In such applications, the possibility of having a completely autonomous electronics now becomes an opportunity. The system can depend on harvesting background energy from the environment for highly long-term functionality, which is akin to organisms like bacteria in biology.”