Ambient backscatterers for low cost and low power wireless applications

Abstract

Sensors that are used in Internet-of-Things (IoT) area are hampered by extremely high costs and excessive battery power consumption – but wireless, reflective, sensor-tags could help address these issues. In agricultural applications: in order to monitor a field of 500 plants, the operating cost will typically rack up hundreds of pounds per field and will gobble tens of milliwatts per sensor. In this thesis we have tried to address some of these shortfalls by opting for each plant to have an antenna, one transistor that acts as a switch, and one microcontroller. Each sensor uses wireless communication based on a reflections technology known as backscatter. The antenna acts as a mirror and when it is illuminated with a signal, it reflects back the wave. The signal comes from an FM radio station and it is freely available in the air. The plant-sensor can modulate the information by a very smart switching of this antenna. We are trying, under laboratory conditions, to combine this low power, low-cost technology with tape-based, flexible nanomaterial printed sensors. As nanotechnology enables flexible inkjet printed electronics to revolutionise IoT applications, we developed a new technology and we hope that our nanomaterial based printed circuit sensors will help push state-of-the-art additive manufacturing in agricultural technology.