UCLA

The recent emergence of the Internet of Things (IoT) has coincided with the popularity of wireless sensor networks (WSNs), which transmit and receive data to and from IoT devices. Wirelessly powered WSNs offer significant advantages over battery-powered WSNs since they do not suffer from issues regarding battery leakage and limited battery life.

This thesis presents two miniaturized wireless and battery-less localization systems for use in WSNs. Both systems comprise a printed circuit board (PCB) having a microchip, on-PCB coils, and resonating capacitors. The microchip, fabricated in the TSMC 180 nm process, is wirelessly powered by an RF signal and transmits back a locked sub-harmonic signal generated from the powering signal, eliminating the need for a power-hungry oscillator. The PCB has a form factor of 17 mm × 12 mm × 0.2 mm. The first system, having a 6 µW power consumption, has been proposed to be used for wireless capsule endoscopy and demonstrates an accuracy of less than 5 mm in ex vivo measurements. Additionally, the system has been verified to detect a motion as small as 50 µm, as well as rates of motion up to 10 bpm. The second system, having a 1.5 µW power consumption, has been proposed to be used for fracture mapping at temperatures up to 250 °C and pressures up to 24 MPa.