Integrated Low-Power Wireless Systems for the Next Generation of IoT, Sensors and Microrobots


Alex Moreno

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2023-261
December 1, 2023

The relentless pursuit of smaller, cheaper, and lower-power wireless electronics has driven the design of novel radio designs such as crystal-free radios, that offer a fully functional wireless node with minimal external components. At Berkeley, the Single-Chip Micro Mote (\scum{}), a 3x\SI{2}{\milli\meter}, \SI{4.2}{\milli\gram} crystal-free 802.15.4 and BLE wireless SoC, was developed to make swarms of mm-scale microrobots a reality. This dissertation will begin by discussing \scum{} in the context of system integration, including the challenge of accurate channel frequency tuning in the face of varying temperature and voltage conditions. By characterizing the RF frequency’s dependence on voltage droop during transmission, we were able to compensate for the RF frequency shift, increasing \scum{}’s 802.15.4 packet payload from 10B to 125B while powered from a solar cell.

Several integrated systems with \scum{} at their core will also be discussed, including a wirelessly-actuated, solar-powered, quarter-sized, \SI{286}{\milli\gram} microrobot MEMS gripper for microrobotics; and a \SI{244}{\milli\gram}, 5x\SI{8}{\milli\meter} BLE \scum{} tag, which was used to track an Asian hornet—feats not possible with commercial off-the-shelf components. The dissertation will conclude with a look at how future crystal-free radios could be designed to address the inherent instability of power sources in low-power systems, potentially pushing the envelope for even smaller, cheaper, lower-power and more reliable wireless electronics.

Advisor: Kristofer Pister and Ali Niknejad