In a pioneering development at the University of Michigan, researchers have come up with a tiny solar-powered sensor that is capable of supplying almost continuous energy. The device consists of a processor, solar cells and a battery, all enclosed in a small frame, measuring just 2.5 by 3.5 by 1 millimeters. Using an industry-standard ARM Cortex-M3 processor, the system contains the lowest-powered commercial-class microcontroller. It consumes about 2,000 times less power in sleep mode than its most energy-efficient counterpart available does today.
This research, presented yesterday at the International Solid-State Circuits Conference in San Francisco has the potential to enable new biomedical implants as well as new devices to monitor buildings, bridges and homes. The new sensor has been designed to spend most of its time in sleep mode, waking briefly every few minutes to take measurements. Claims are that its total average power consumption is less than 1 nanowatt.
According to the developers, their method for managing power is the key innovation. The processor only needs about half of a volt to operate, but its low-voltage, thin-film Cymbet battery puts out close to 4 volts. The voltage, which is essentially the pressure of the electric current, must be reduced for the system to function most efficiently.