Novel microchip can operate even when battery runs out, researchers claim

Engineers claim to have developed an innovative microchip, called BATLESS, that can continue to operate even when the battery runs out, an advance that may lead to longer lasting devices, especially those which demand extreme power efficiency.

BATLESS, as described at International Solid-State Circuits Conference (ISSCC) 2018 Conference held in the US, is designed with a new power management technique that allows it to self-start and continue to function under dim light without any battery assistance, using a very small on-chip solar cell.

According to the researchers, including those from the National University of Singapore (NUS), the microchip may substantially reduce the size of batteries required to power sensor nodes in Internet of Things (IoT) devices which are connected with each other over the internet.

They said the new microchip could make the IoT sensor nodes 10 times smaller and cheaper to produce.

"We have demonstrated that batteries used for IoT devices can be shrunk substantially, as they do not always need to be available to maintain continuous operation," said lead scientist, Massimo Alioto from NUS.

"Tackling this fundamental problem is a major advancement towards the ultimate vision of IoT sensor nodes without the use of batteries, and will pave the way for a world with a trillion IoT devices," Alioto said.

The researchers said when the battery energy is available, the chip runs in minimum-energy mode to maximise the battery lifetime.

However, they said when the battery is exhausted, the chip switches to the minimum-power mode and operates with a tiny power consumption of about half a nanoWatt -- a billion times smaller than the power consumption of a smartphone during a phone call.

This power, the scientists noted, can be provided by a very small on-chip solar cell that is about half a square millimetre in area, or other forms of energy available from the environment, such as vibration or heat.

Despite being in minimum-power mode when battery is not available, the reduced speed of the microchip is still adequate for numerous IoT applications that need to sense parameters that vary slowly in time like temperature, humidity, light, and pressure, they added.

"BATLESS is the first example of a new class of chips that are indifferent to battery charge availability," Alioto said.

"In minimum-power mode, it uses 1,000 to 1,00,000 times less power, compared to the best existing microcontrollers designed for fixed minimum-energy operation," he added.

According to the NUS researchers, BATLESS microchip covers a very wide range of possible energy, power, and speed trade-offs, as allowed by the flexibility offered through the two different modes.