What are microsystems? And, what is different about their mechanics? And nano?
Microsystems are integrated systems of small size where the feature sizes are generally of micron dimensions, but sometimes a little larger extending up to millimeters. More important than this "size" qualification, the unique feature of microsystems is the extent to which actuation, sensing, control, manipulation, and computation are integrated in the same system. The notion of integration is also inherent in the way microsystems are manufactured. The same applies to modeling and design. And, that is why special attention is given to the subject we will be studying in this course, by focussing on mechanics.
Microsystems field is more popularly known as MEMS--Microelectromechanical systems. With its early origins in mid-to-late 1960s and accelerated development since late eighties, MEMS field has sufficiently matured now. The "gee-whiz" "show-and-tell" era of "cool" miniaturized devices has almost ended; large and small MEMS industries are seriously competing in the commerical market. Efforts are underway to optimize the performance and cost and to improve the reliability of MEMS. Microfabrication is expensive and time-consuming, which makes it uneconomical to rely upon "build-and-test" approach. Therefore, the issues of simulating them and designing them have become very important. There are now a large number of companies whose mission is developing software for modeling and designing MEMS.
Is modeling and design of MEMS different from that of traditional macro ststems? The answer to this is no and yes: "No" beacuse there is almost no new physics or chemistry in most MEMS devices. And therefore, the governing equations are the same as we know them at the macro scale; "Yes" because there are scaling effects that change coefficients in these equations radically and bring about interesting consequences. And then there is integration. How do you simulate and design a device that tightly couples effects of several domains, sometimes all in a single structure? By "domains", we refer here to physical and chemical phenomena such as elastic, electrostatic, thermal, magnatic, dynamics, optical, fluidic, etc. Thus, we often need to solve coupled equationas that govern two or more domains simulataneously. Now, think about the system-level issues. How do you design a system that integrates components of several types such as elastic structures, electronic circuits, fluidic elements, optical units, etc., -- all on the same platform? We will discuss these issues in this course. But our focus will be on mechanics.
While our focus is on modeling and design, of necessity, we will also learn about microfabrication and the operating principles of various MEMS devices. So, you get a bird's eye view of the MEMS field as a bonus.
And then there is nano... Even before microsystems field matured, nano entered the scene. This course will not delve into this topic but will limit itself to what is popularly known as NEMS--nanoelectromechanical systems. Thermoelastic damping is one topic that goes to the level of nano or sub-micro dimensions. We might consider some other topics, if there is interest and if time permits.