Design and Technology of Submillimeter Autonomous Microsystems:
E.C. Kan, Z. Liu, P. Wang, M. Kim and Y.N. Shen
Cornell University, US
Si technology has made unprecedented progress in the past 40 years in scale, cost, complexity and yield. There are many predictions on the remaining scaling possibilities in Si technology (Wong 1999), but two categories of genuine knowledge are crucial in any kind of future microsystem integration: 1) the low-cost, high-yield manufacturing of nanoscale layers and planar resolution, 2) the hierarchical design system for physical technology and functional design to handle the immense complexity. These two establishment in Si technology are enough to make it the choice for the nanotechnology integration platform. Most efforts in Si technology have focused on functional modules for computing and control applications, though in the last 15 years more attempts have been made in integrated wireless communication (Darpatech 1999) and mechanical sensing and actuation (Kovacs 1998). However, for a submillimeter autonomous microsystem whether biological or inorganic, if the reproduction module is excluded, the most critical system component is power generation, with all other functional modules of communication, sensing, actuation, computing and control operated under the available power budget. This real-power integration scheme (for both continuous and peak power) has a deep impact on the choice of technology and module implementation.
Small insects, such as fleas and mites, are submillimeter autonomous microsystems and their ways of operation are good examples of the real-power paradigm. Information collection, processing and transmission are usually not optimized for bandwidth as bit per second, but for power per bit based on the available power budget. Not only that we can learn from the system integration principles of these small insects, but there is a more intriguing question. If we remove the constraint on reproduction by providing a controlled manufacturing process with a totally different technology integration scheme, can we achieve an autonomous microsystem that is comparable in form factor, but much better in specific functionality?
Several schemes for power generation under small system size in Si technology will be compared (Amirtharajah 1998, Darpatech 1999). We will then argue that the new technology integration of EEPROM and MEMS can provide many critical features to functional modules that meet the small and unstable power budget (Kan 2001). This is mainly achieved by smart use of the nonvolatile charges. We will demonstrate prototypes of electrostatic repulsive forces for micro-mechanical structures, static-charge antenna for near-field transmission, large dynamic-range chemical sensors, and vibration-based self-starting generators. Comparison with other options including biological modules will be made in view of integration capabilities, power efficiency and overall controllability.
NSTI Nanotech 2003 Conference Technical Program Abstract