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Researchers have demonstrated for the first time that devices that run on almost zero power can transmit data across distances of up to 2.8 kilometers--breaking a long-held barrier and potentially enabling a vast array of interconnected devices. For example, flexible electronics--from knee patches that capture range of motion in arthritic patients to patches that use sweat to detect fatigue in athletes or soldiers--hold great promise for collecting medically relevant data.
But today’s flexible electronics and other sensors that can’t employ bulky batteries and need to operate with very low power typically can’t 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. By contrast, this study’s long-range backscatter system, which uses reflected radio signals to transmit data at extremely low power and low cost, achieved reliable coverage throughout a 4,800-square-foot house, an office area covering 41 rooms and a 1-acre vegetable farm.Image credit: Dennis Wise/University of Washington
