Starting with a list of specifications for the MEM device or system, the design process begins with the identification of the general operating principles and overall structural elements, then proceeds onto analysis and simulation, and finally onto outlining of the individual steps in the fabrication process. This is often an iterative process involving continuous adjustments to the shape, structure, and fabrication steps. The layout of the lithographic masks is the final step before fabrication and is completed using specialized CAD tools to define the two-dimensional patterns.

Early design considerations include the identification of the general sensing or actuation mechanisms based on performance requirements. For instance, the output force requirement of a mechanical microactuator may favor thermal or piezoelectric methods and preclude electrostatic actuation. Similarly, the choice of piezoresistive sensing is significantly different from capacitive or piezoelectric sensing. The interdisciplinary nature of the field brings together considerations from a broad range of specialties, including mechanics, optics, fluid dynamics, materials science, electronics, chemistry, and even biological sciences. On occasion, determining a particular approach may rely on economic considerations or ease of manufacture rather than performance. For example, the vast majority of pressure sensors use cost-effective piezoresistive sense elements instead of the better performing, but more expensive, resonant-type sense structures.

The design process is not an exact analytical science but rather involves developing engineering models, many for the purpose of obtaining basic physical insights. Computer-based simulation tools using finite-element modeling are convenient for analyzing complex systems. A number of available...