RF-powered, backscatter-based cameras

RF-powered devices equipped with general-purpose microcontrollers face energy limitation constraints for performing arbitrarily complex sensing and computation tasks. While richer capabilities such as image capture and processing would enable many new RF-powered use-cases, this energy limitation narrows the application space. Enabling richer sensing tasks has two main challenges: efficiently retaining and utilizing harvested energy, and storing and communicating large quantity of sensor data. This paper reviews the WISPCam design, an RF-powered programmable camera. Taking into account both of the mentioned challenges, WISPCam integrates an off-the-shelf VGA camera which is a rich sensor example energy and data wise. The paper also presents an ultra-low power scheme that is able to provide periodic updates on charge state of the device before enough energy has been accumulated for the camera to capture an image. This paper presents a novel data storage and bi-directional communication scheme that enables reliable transfer of complete images to an RFID reader application even when packets are lost or the device runs out of energy.