Self-powered Sub-nanowatt Microcontroller with On-chip Solar Cell for IoT Devices

Technology Overview

This technology offer is a sub-nanowatt microcontroller that can continue to operate even when the device battery runs out of energy. A novel power management technique allows the microcontroller to self-start and continue to function under dim light conditions, without any battery assistance, by using a tiny on-chip solar cell. As such, this design is battery-indifferent. This design can facilitate the size reduction of batteries used to power IoT sensor nodes, making them potentially 10 times smaller and cheaper to produce.

Technology Features & Specifications

The battery-indifferent 16-bit microcontroller can switch between two different modes:

  • Minimum-energy – maximising battery lifetime when battery energy is available
  • Minimum-power – minimising power consumption to about 0.5nW when battery is exhausted

This design includes a new power management technique that enables operations to be self-started, with power supplied by a tiny on-chip solar cell about 0.5 square millimetres in area, or by other forms of energy available from the environment, such as vibration or heat.

Operations can continue down to 50-lux indoor light intensity, which is equivalent to the dim light available at twilight.

This design enables the capability to sense, process, timestamp and store events of interest without interruption, and for such data to be wirelessly transmitted to the cloud when battery power becomes available again.

Potential Applications

Even when in minimum-power mode when battery power is not available, the reduced processing speed of the microcontroller is still adequate for many IoT applications, such as those that sense parameters varying slowly in time, including temperature, humidity, light, and pressure. Thus, this technology offer is suited for use in smart buildings, environmental monitoring, energy management, etc.

Customer Benefits

This technology offer allows IoT devices to be energy self-sufficient, without the need to be serviced regularly for battery changes. Thus, these IoT devices can be deployed on a massive scale, including in remote locations where regular servicing is difficult or impossible.

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