Graphene harvester runs a temperature sensor from power line magnetic fields
Researchers at the University of Arkansas and the University of Michigan have powered a temperature sensor using energy harvested from the magnetic field around electrical power lines.
The prototype uses a graphene inductor at the 60 Hz mains frequency used in the US. A custom circuit converts the harvested AC signal to DC and charges capacitors that supply the sensor. The reported load operates at nanowatt power levels. “The inductor adds charge to these capacitors at a slow rate,” said Arkansas physicist Paul Thibado. Its charging rate exceeds the sensor’s consumption, allowing charge to accumulate.
The storage element matters because the field and the load are not necessarily available on the same timetable. A capacitor can supply a measurement during a temporary interruption, provided its stored energy and leakage permit it. Adding a transmitter or increasing the sampling rate would change that balance. The demonstrated load is a temperature sensor, so the result does not establish an energy budget for a complete wireless node.
The paper appears in the Journal of Vacuum Science & Technology B. NTS Innovations holds the exclusive licence to develop the graphene harvesting technology commercially.
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Image: The graphene sensor research team. Russell Cothren / University of Arkansas. Supplied with the university release. Image source.
