Battery life extended by Bristol voltage detector

The voltage detector chip, developed by Dr Bernard Stark and colleagues in the Bristol Electrical Energy Management Research Group at Bristol University, requires only a few picowatts to activate other circuits.

In this way it could be used to control industrial, environmental or medical sensors that consume no power when waiting for a particular event to happen. Instead, the chip would switch on the sensor in response to the energy contained in the event itself, such as the infrared light in a TV remote control, the motion of a tracker, or the sound waves generated by a component rattling, said Stark.

The device is based on the same principle as the chips used inside computers to monitor power supply rails to ensure the voltage does not dip below a certain threshold.

The researchers have developed a detector in which the chip responds to a very low voltage threshold, he said.

“The chip detects voltage over a certain threshold, in our case 0.5 volts, and uses almost no power, around 1,000-10,000 times less power than you would need to monitor a voltage rail,” he said.

In this way, the chip allows designers to develop circuits that perform continuous monitoring without using battery power, and which can be woken up wirelessly.

Power management techniques are used to ensure the current is switched off as soon as it is inactive, said Stark.

“Once the voltage detector has triggered and the sensor has given its information, there is no need for it to be burning any power, so we actively switch that power off again,” he said.

The technology could allow battery size to be reduced to the point at which they can be embedded into the sensors themselves. It could also extend the life of the batteries such that they last as long as the sensor.

What’s more, because the sensor is only switched on to capture the event that it is monitoring, it could also eliminate the need for companies to filter through large amounts of irrelevant data to reach the information they are looking for, said Stark.