Ultra-low power event-driven sensing

The instrumentation industry requires remote monitoring devices that continuously listen and consume minimal power. Devices may be listening as sensors, measuring physical parameters such as temperature, vibration or leakage, or they may be listening for remote control to wake up a device and trigger an action such as communicating data.

However, always-on sensing draws continuous power, and therefore, in many situations, this kind of monitoring is not viable, as it would either require sensors to be wired into the mains, or frequent battery replacement.

We recently developed an integrated circuit that listens to sensors continuously, using only the power from the sensor, enabling the rest of the electronics to be fully powered down. Batteries now no longer need replacing, as lifetimes of decades can be achieved. Currently the technology has a fixed threshold of 0.5V, which limits its use to a subset of sensors that produce signals of several volts and a subset of applications where a sensor wake up threshold of 0.5V is applicable.

This project aims to further develop the wake up technology to address a much wider range of sensor applications. The project will reduce the threshold from 0.5V to 10mV and will also enable it to be tuned over a large range according to the application. We will design an ultra-low power (less than 10 nanowatt) configurable pre- amplifier to interface with the detector circuit, whilst still keeping all other circuitry powered off until an event occurs. This level of amplifier power consumption is smaller than the self-leakage from a small coin cell, so in practice will not reduce the lifetime of the sensor.

This project will design and evaluate a prototype sensor device with low, variable trigger threshold and lifetime limited by battery self-leakage only. We will commercialise the technology through sensor manufacturers by providing modules to be incorporated within their devices.