Autonomous Microsystems for Downhole Applications: Design Challenges, Current State, and Initial Test Results.

This paper describes two platforms for autonomous sensing microsystems that are intended for deployment in chemically corrosive environments at elevated temperatures and pressures. Following the deployment period, the microsystems are retrieved, recharged, and interrogated wirelessly at close proximity. The first platform is the Michigan Micro Mote for High Temperature (M³HT), a chip stack 2.

Energy Harvesting for GaAs Photovoltaics Under Low-Flux Indoor Lighting Conditions.

GaAs photovoltaics are promising candidates for indoor energy harvesting to power small-scale (≈1 mm) electronics. This application has stringent requirements on dark current, recombination, and shunt leakage paths due to low-light conditions and small device dimensions. The power conversion efficiency and the limiting mechanisms in GaAs photovoltaic cells under indoor lighting conditions are studied experimentally.

A 10.6mm Fully-Integrated, Wireless Sensor Node with 8GHz UWB Transmitter.

This paper presents a complete, autonomous, wireless temperature sensor, fully encapsulated in a 10.6mm volume. The sensor includes solar energy harvesting with an integrated 2 μAh battery, optical receiver for programming, microcontroller and memory, 8GHz UWB transmitter, and miniaturized custom antennas with a wireless range of 7 meters.

MBus: An Ultra-Low Power Interconnect Bus for Next Generation Nanopower Systems.

As we show in this paper, I/O has become the limiting factor in scaling down size and power toward the goal of invisible computing. Achieving this goal will require composing optimized and specialized-yet reusable-components with an interconnect that permits tiny, ultra-low power systems. In contrast to today's interconnects which are limited by power-hungry pull-ups or high-overhead chip-select lines, our approach provides a superset of common bus features but at lower power, with fixed area and pin count, using fully synthesizable logic, and with surprisingly low protocol overhead.