Solar powered energy-harvesting sensor system developed

Washington, Feb 10 (ANI): Scientists at the University of Michigan, US, have developed a 9 cubic millimeter solar-powered sensor system that can harvest energy from its surroundings to operate nearly perpetually.

The U-M system's processor, solar cells, and battery are all contained in its tiny frame, which measures 2.5 by 3.5 by 1 millimeters. It is 1,000 times smaller than comparable commercial counterparts.

The system could enable new biomedical implants as well as home-, building- and bridge-monitoring devices.

It could vastly improve the efficiency and cost of current environmental sensor networks designed to detect movement or track air and water quality.ith an industry-standard ARM Cortex-M3 processor, the system contains the lowest-powered commercial-class microcontroller.

It uses about 2,000 times less power in sleep mode than its most energy-efficient counterpart on the market today.

"Our system can run nearly perpetually if periodically exposed to reasonable lighting conditions, even indoors," said David Blaauw, an electrical and computer engineering professor.

"Its only limiting factor is battery wear-out, but the battery would last many years," he added.

"The ARM Cortex-M3 processor has been widely adopted throughout the microcontroller industry for its low-power, energy efficient features such as deep sleep mode and Wake-Up Interrupt Controller, which enables the core to be placed in ultra-low leakage mode, returning to fully active mode almost instantaneously," said Eric Schorn, vice president, marketing, processor division, ARM.

"This implementation of the processor exploits all of those features to the maximum to achieve an ultra-low-power operation," he added.

The sensor spends most of its time in sleep mode, waking briefly every few minutes to take measurements.

Its total average power consumption is less than 1 nanowatt. A nanowatt is one-billionth of a watt.

According to the developers, the key innovation is their method for managing power.

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.

One way the U-M engineers made the voltage conversion more efficient is by slowing the power management unit's clock when the processor's load is light.

Now, the designers are working with doctors on potential medical applications.

The system could enable less-invasive ways to monitor pressure changes in the eyes, brain, and in tumors in patients with glaucoma, head trauma, or cancer. (ANI)