New devices can transmit information with almost zero power

Scientists have developed devices that run on almost zero power and can transmit data across distances of up to 2.8 kilometers, paving the way for a vast array of 'smart' interconnected devices.
The team built a contact lens prototype and a flexible patch that attaches to human skin, which successfully transmitted information across a 3,300-square-foot atrium.
Previous smart contact lens designs can achieve a three- foot range, researchers said.
Current flexible electronics and sensors that can operate with very low power typically can not communicate with other devices more than a few feet or meters away.
This limits their practical use in applications ranging from medical monitoring and home sensing to smart cities and precision agriculture.

The long-range backscatter system, developed by researchers at the University of Washington in the US, uses reflected radio signals to transmit data at extremely low power and low cost.

The device achieved reliable coverage throughout 4,800- square-foot house, an office area covering 41 rooms and a one-acre vegetable farm.
"Until now, devices that can communicate over long distances have consumed a lot of power. The tradeoff in a low-power device that consumes microwatts of power is that its communication range is short," said Shyam Gollakota, associate professor at UW.
"Now we've shown that we can offer both, which will be pretty game-changing for a lot of different industries and applications," said Gollakota.

The team's latest long-range backscatter system provides reliable long-range communication with sensors that consume 1,000 times less power than existing technologies capable of transmitting data over similar distances.
It is an important and necessary breakthrough toward embedding connectivity into billions of everyday objects.
The system will be commercialised by Jeeva Wireless, a company founded by the UW team.
The sensors are so cheap - with an expected bulk cost of 10 to 20 cents each - that farmers looking to measure soil temperature or moisture could affordably blanket an entire field to determine how to efficiently plant seeds or water.

Other potential applications range from sensor arrays that could monitor pollution, noise or traffic in "smart" cities or medical devices that could wirelessly transmit information about a heart patient's condition around the clock.