One of the biggest challenges for small wearable devices is how to power them. The smaller the devices are, the less space there is for batteries making runtime an issue in some instances. A group of researchers led by Huanyu “Larry” Cheng from Penn State University has developed a new method of powering wearable devices using energy harvested from radio waves.
Current sources of energy for wearable health-monitoring devices have drawbacks. Solar power can only harvest energy when exposed to the sun, while triboelectric devices can only harvest energy when the body is in motion. Cheng says that the researchers aren’t trying to replace those methods of power but are trying to provide additional consistent energy for wearable devices. The team developed a stretchable wideband dipole antenna system that can wirelessly transmit data collected from health-monitoring sensors.
The device consists of a pair of stretchable metal antennas integrated onto conductive graphene with a metal coating. The wideband design of the system allows it to retain frequency functions even when stretched, bent and twisted. That system is connected to a stretchable rectifying circuit to create a rectified antenna that can convert energy from electromagnetic waves into electricity.
The electricity can then be used to power wireless devices or charge energy storage devices like batteries and supercapacitors. Researchers believe the technology is a building block and that it can be combined with wireless transmissible data devices to provide a critical component to work with existing sensor modules developed by the team. The next step for the researchers will be to explore miniaturized versions of the circuits and work on developing the rectifier’s stretchability.
The team believes they have created a platform that could be easily combined and applied with other modules developed in the past. Researchers will explore opportunities to extend or adapt the new technology for other applications.