Smart Dust requires both evolutionary and revolutionary advances in miniaturization, integration, and energy management. Designers can use microelectromechanical systems (MEMS) to build small sensors, optical communication components, and power supplies, whereas microelectronics provides increasing functionality in smaller areas, with lower energy consumption. Figure 1 shows the conceptual diagram of a Smart Dust mote. The power system consists of a thick-film battery, a solar cell with a charge-integrating capacitor for periods of darkness, or both. Depending on its objective, the design integrates various sensors, including light, temperature, vibration, magnetic field, acoustic, and wind shear, onto the mote. An integrated circuit provides sensor-signal processing, communication, control, data storage, and energy management. A photodiode allows optical data reception. We are presently exploring two transmission schemes: passive transmission using a corner-cube retroreflector, and active transmission using a laser diode and steerable mirrors. The mote's minuscule size makes energy management a key component. Current battery and capacitor technology stores approximately 1 joule per cubic mm The Smart Dust project is probing microfabrication technology's limitations to determine whether an autonomous sensing, computing, and communication system can be packed into a cubic-millimeter mote to form the basis of integrated, massively distributed sensor networks.

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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.

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