Researchers at the University of Michigan have developed a tiny solar powered sensor – 1,000 times smaller than comparable commercial counterparts.
The system’s processor, solar cells, and battery are all contained in a frame measuring 2.5 x 3.5 x 1mm. The system contains the ARM Cortex-M3 processor, which uses about 2,000 times less power in sleep mode than its most energy-efficient counterpart on the market today.
According to electrical and computer engineering professor David Blaauw, the system can run nearly perpetually if periodically exposed to reasonable lighting conditions, even indoors and the only limiting factor is the life of the battery.
The sensor usually operates in sleep mode, waking briefly every few minutes to take measurements. Its total average power consumption is less than 1 nanowatt. – one-billionth of a watt.
ARM Cortex-M3 processors are popular in the micro controller industry for their low-power, energy efficient features such as deep sleep mode and Wake-Up Interrupt Controller, which enables the core to be placed in very low leakage mode, returning to fully active mode almost instantaneously.
So what could such a tiny solar powered sensor be used for? The researchers say the device could vastly improve the efficiency and cost of current environmental sensor networks designed to detect movement or track air and water quality.
The system could also enable new biomedical implants and the designers are working with doctors on potential medical applications such as less-invasive ways to monitor pressure changes in the eyes, brain, and in tumours in patients with glaucoma, head trauma, or cancer. In the body, the sensor could conceivably harvest energy from movement or heat, rather than light.
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