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NUS engineers invent BATLESS microchip that helps IoT devices achieve battery indifference

NUS engineers invent BATLESS microchip that helps IoT devices achieve battery indifference

The National University of Singapore (NUS) announced
that NUS Associate Professor Massimo Alioto and his team of engineers have invented a new
smart microchip that can self-start and continue to operate even when
the battery runs out of energy.

The novel technology would help maximise the lifetime and enables
smaller and cheaper Internet of Things (IoT) devices. This research breakthrough would
substantially reduce the size of batteries required to power IoT sensor nodes,
making them 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. 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,” said Associate Professor Massimo Alioto from the
Department of Electrical and Computer Engineering at the NUS Faculty of
Engineering.

IoT devices, such as sensors, are often deployed on a
massive scale and in places that are usually remote and difficult to service
regularly, thus making their self-sufficiency essential. As such, one of
the key challenges of IoT devices is to have long-lasting operation under
tightly constrained energy sources, thus demanding high level of power
efficiency.

According to the press release, current batteries in IoT
devices are much larger and up to 3 times more expensive than the single
chip they power. Their size is determined by the sensor node lifetime, which
directly affects how often they need to be changed. This has implications on
maintenance cost and impact on the environment when batteries are disposed. However,
existing IoT devices cannot operate without battery, and small batteries are
fully discharged more frequently. Hence, battery miniaturisation often results
in highly discontinuous operation of IoT devices, as they stop functioning
every time the battery runs out of energy.

To address this technology gap, a team of engineers from the
NUS has developed an innovative microchip, named BATLESS, that can continue to
operate even when the battery runs out of energy.

BATLESS is designed with a novel 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. The microchip is
also equipped with a new power management technique that enables operations to
be self-started, while being powered directly by the tiny on-chip solar cell,
with no battery assistance.

“BATLESS is the first example of a new class of chips that
are indifferent to battery charge availability. In minimum-power mode, it uses
1,000 to 100,000 times less power, compared to the best existing
microcontrollers designed for fixed minimum-energy operation. At the same time,
our 16-bit microcontroller can also operate 100,000 times faster than others
that have been recently designed for fixed minimum-power operation. In short,
the 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,” Associate Professor Alioto added.

Battery indifference is the ability for IoT devices to
continue operations, even when the battery is exhausted. It is achieved by
operating in two different modes: minimum-energy and minimum-power.

When the battery energy is available, the chip runs in
minimum-energy mode to maximise the battery lifetime. However, 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. Power 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,
including temperature, humidity, light, and pressure. Among many other
applications, BATLESS is very well suited for smart buildings, environmental
monitoring, energy management, and adaptation of living spaces to occupants’
needs.

Such ability to switch between minimum energy and minimum
power mode means that the BATLESS microchip enables the IoT device to uninterruptedly
sense, process, capture and timestamp events of interest, and for such valuable
data to be wirelessly transmitted to the cloud when the battery becomes
available again.

The research breakthrough has been presented at the
International Solid-State Circuits Conference (ISSCC) 2018 conference in San
Francisco, the premier global forum for presenting advances in solid-state
circuits and systems-on-a-chip.

The NUS Engineering team is now exploring new
solutions to build complete battery indifferent systems that cover the entire
signal chain from sensor to wireless communications, thus expanding the current
work on microcontrollers and power management. The research team aims to
demonstrate a solution that shrinks the battery to millimetres, with the
long-term goal of completely eliminating the need for it.

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