Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. They can be deeply embedded in the physical world or spread throughout our environment. The missing elements are an overall system architecture and a methodology for systematic advance. To this end, we identify key requirements, develop a small device that is representative of the class, design a tiny event-driven operating system, and show that it provides support for efficient modularity and concurrency-intensive operation. Our operating system fits in 178 bytes of memory, propagates events in the time it takes to copy 1.25 bytes of memory, context switches in the time it takes to copy 6 bytes of memory and supports two level scheduling. The analysis lays a groundwork for future architectural advances.

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We have demonstrated an autonomous two-legged microrobot which has taken its first steps. The body of the robot is fabricated in a planarized silicon-on-insulator (SOI), two-layer polysilicon process and is 8.5 mm x 4 mm x 0.5 mm in size. We previously reported initial leg motion from an off-board controller but have now incorporated control and power supplies onto the robot, resulting in autonomous operation for the first time. This solar-powered microrobot has two, one degree-offreedom (DOF) legs and drags its tail end. Leg motion is generated via electrostatic inchworm motors on the robot body. The robot is a three chip hybrid assembled from one chip which contains the robot's motors and legs, a second chip which integrates both solar cells and high voltage buffers, and a third chip which incorporates CMOS circuitry for sequencing the legs. The robot has demonstrated 3 mm of motion shuffling sideways and has lifted its front end more than 300 µm above the surface. The total weight of the three-chip robot is only 10.2 mg.

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Technological progress in integrated, low-power, CMOS communication devices and sensors makes a rich design space of networked sensors viable. They can be deeply embedded in the physical world or spread throughout our environment. The missing elements are an overall system architecture and a methodology for systematic advance. To this end, we identify key requirements, develop a small device that is representative of the class, design a tiny event-driven operating system, and show that it provides support for efficient modularity and concurrency-intensive operation. Our operating system fits in 178 bytes of memory, propagates events in the time it takes to copy 1.25 bytes of memory, context switches in the time it takes to copy 6 bytes of memory and supports two level scheduling. The analysis lays a groundwork for future architectural advances.