University of Washington engineers present the first battery-free cellphone design that consumes only a few micro-watts of power. The new design can sense speech, actuate the earphones, and switch between uplink and downlink communications, all in real time. The system developed by researchers from the Allen School of Computer Science & Engineering and the UW Department of Electrical Engineering optimizes transmission and reception of speech while simultaneously harvesting power which enables the battery-free cellphone to operate continuously.