Tham khảo tài liệu 'an introduction to mems engineering - nadim maluf and kirt williams part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 80 MEM Structures and Systems in Industrial and Automotive Applications 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 programs such as ANSYS ANSYS Inc. of Canonsburg Pennsylvania and CoventorWare Coventor Inc. of Cary North Carolina can simulate mechanical thermal and electrostatic structures see Figure . Substantial efforts are currently under way to develop sophisticated programs that can .
