About MEMS

The term MEMS is an acronym for MicroElectroMechanical Systems. In this context,

• “Micro” means that the devices are extremely tiny, in the order of micrometers or smaller.
• “Electro” means that some electrical component is involved.
• “Mechanical” means that the system performs some mechanical motion.
• “Systems” refers to the fact that all these features are combined in one package.

MEMS technology exploits the existing microelectronics infrastructure to create complex machines on a micrometer scale. Extensive applications for these devices exist in both commercial and industrial systems. Well-known components such as integrated silicon pressure sensors, accelerometers, and motion detectors have found use for several years in automotive and industrial applications. Research activity in microfluidics is changing medical-diagnostic processes such as DNA analysis, and it is spurring the development of successful commercial products.

MEMS is Multiphysics by nature

It is common knowledge that MEMS are made of tiny electromechanical components, but some engineers do not appreciate the fact that almost all MEMS devices involve multiple areas of physics—multiphysics. At a minimum, MEMS devices involve at least the electrical and mechanical sciences. It is also common that the electronic and mechanic elements are coupled through thermal or electrochemical effects, thereby adding a third or fourth physical phenomenon to the system.

This multiphysics nature of MEMS devices requires that the system designer has a vast understanding and knowledge of these various branches of physics. Because some microscale effects are totally new or behave differently than at the macroscale, engineers require new system-design philosophies. The MEMS engineer is a true systems designer, handling several physical phenomena simultaneously—and COMSOL Multiphysics and the MEMS Module can do the same.

Microfabrication

Most MEMS devices are manufactured using lithography-based microfabrication, a technology that the microelectronics industry has refined for highly integrated circuits. Thanks to these efforts there are excellent methodologies and facilities for mass production. Suppliers can thus set the price of microsystems at a totally different level compared to their macro-scale counterparts.

Lithographic fabrication techniques, however, do present some limitations on geometrical structures in MEMS devices. Microfabrication is based on planar technology where the components are usually flat. From the modeling point of view, a flat structure presents some challenges, specifically in mesh generation and in finding numerical solutions. To get accurate solutions, the shape of a single triangle (2D) or tetrahedron (3D) in the mesh should be as regular as possible. In flat structures you can achieve regularity by decreasing the mesh size to accommodate the shortest distances, but doing so increases memory requirements. Fortunately, advances in modeling techniques such as mesh rescaling, mesh mapping, and mesh extrusion can reduce the mesh size and relieve memory demands. In addition, certain industries have moved away from the use of silicon in favor of glasses and plastics, and we are now seeing the emergence of chips in biotechnology that include microfluidic systems that can be regarded as true MEMS devices (Ref. 1).

MEMS Simulation Software - The MEMS Module

MEMS pioneers in both research and industrial organizations have solved several challenges in the modeling and manufacturing areas. They have been able to apply existing tools to help analyze the behavior of MEMS devices through numerical methods. Meanwhile, it is apparent that the time is right to introduce new tools that demonstrate how well finite-element-based numerical solvers perform in this area. The MEMS Module, can help researchers, designers, and instructors explore the electro-thermal-chemical-mechanical behavior of microsystem components, as well as the behavior of microfluidic devices, and further develop these fascinating new areas.

References

(1). Julian Gardner and others, Microsensors, MEMS and Smart Devices, John Wiley & Sons, 2001.

(2). System Planning Corporation, Market Survey, 1999.

Read more: MEMS Module Overview