MEMS technology is enabling the development of inexpensive, autonomous wireless sensor nodes with volumes ranging from cubic mm to several cubic cm. These tiny sensor nodes can form rapidly deployed, massive distributed networks to allow unobtrusive, spatially dense, sensing and communication. MEMS enable these devices by reducing both the volume and energy consumption of various components. This paper will review some of the wireless sensor nodes under development and applicable MEMS devices for small and efficient optical communication, micropower generation, and sensing. In addition, CMOS post-process micromachining will be discussed as a method of achieving low cost and high integration. 1.

Abstract—A low-energy successive approximation analog-todigital converter (ADC) targeted for use in distributed sensor networks is presented. The individual nodes combine sensing, computation, communications, and power into a tiny volume. Energy is extremely limited, forcing the nodes to operate with very low duty cycles. This paper describes the design and implementation of an ADC to meet the unique requirements of sensor networks. The ADC reported here consumes 31 pJ/8-bit sample at 1-V supply and 100 kS/s, with a standby power consumption of 70 pW. This energy consumption is one of the lowest ever reported. Index Terms—Analog-to-digital converter (ADC), charge redistribution, CMOS, energy, low power, sensor networks, Smart Dust, successive approximation.

The Smart Dust project aims to explore the limits of system integration by packing an autonomous sensing, computing, and communication node into a cubic millimeter mote that will form the basis of massive distributed sensor networks, thus demonstrating that a complete system can be integrated into 1mm3. Effectively exploring this space requires new approaches to design that emphasize energy and volume constraints over all others. To this end a 16 mm3 autonomous solar-powered sensor node with bi-directional optical communication has been demonstrated, with smaller nodes forthcoming. System integration limits will shrink even further as carbon nanotube technology matures.