IoT without batteries?

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Power supply is one of the major challenges for IoT devices. But not for an innovative microchip with flexible power management.

In IoT devices, the power supply is much larger and more expensive than the chip that it powers. This is an obstacle for certain developments, such as in the direction of further miniaturization. On the one hand, the devices are expensive to maintain if the batteries are too small, since they have to be replaced frequently. On the other hand, current IoT devices without battery support simply stop working. In other words, “to be on the safe side” energy storage units must have a certain capacity.

Energy-self-sufficient systems with energy harvesters, such as solar cells or thermocouples that continuously recharge with small amounts of energy from the battery surroundings, at least provide some “relief”. But here, too, the device stops working immediately if the battery is empty.

A 16-bit microchip developed at the National University of Singapore (NUS) called BATLESS aims to overcome precisely this limitation. With new power management technology, it starts on its own and works with the help of a tiny on-chip solar cell with no battery support. IoT sensor nodes are able to work with a ten times smaller and less expensive battery, as they no longer have to guarantee the function of an IoT node.

Flexible power management

The microchip from Singapore works in two different modes: minimum energy and minimum power. If it gets its energy from the battery, minimum energy mode maximizes the running time. When the battery is “exhausted”, it changes to minimum power mode. Consumption is then about half a nanowatt, which comes from the solar cell with an area of half a square millimeter. The chip uses 1,000 to 100,000 times less power than the best existing microcontrollers designed for minimum-energy operation. The researchers also claim that the 16-bit microchip can operate 100,000 times faster than conventional models.

Even without battery support, the two modes of the BATLESS chip enable events in the surroundings to be recorded without interruption so that they can then be transmitted wirelessly when the battery is sufficiently charged.

Next steps

The research team demonstrated the new technology at a light intensity of 50 lux, which is equivalent to twilight conditions. The battery is to be “shrunk” to just a few millimeters with the aim of completely eliminating it some time in the future. Considering the expected billions of IoT devices we can expect to see in the future, this is surely a goal which, based loosely on Shakespeare, is “to be desired with the utmost ardour”.

Power management (Image: pixabay/intografics).

A new chip uses 1,000 to 100,000 times less power than the best existing microcontrollers designed for minimum-energy operation. (Image: pixabay/intografics).