Hi all, gh56 I saw that you have not been able to touch upon BioMems yet. I took this class during my last undergraduate semester and I would like to give you a little information about it from what I understood from the class. First, BioMems stands for Biological or Biomedical micro-electro-mechanical-systems. In terms of meters, we are talking about 10e-6, therefore these are very small devices that integrates mechanical and electrical components (such as sensors, transducers, actuators) that can sense, measure, communicate and act. They have a biological or biomedical function and application. For example, a microcantilever transducer can be produced and can be coated with antibodies that captures a certain virus while ignoring the other components in the sample, this is a chemical sensor array. Another example of BioMems, is the lab-on-a-chip device (a small, portable, low cost and easy to use device) which uses microfluidics to measure and diagnose and it only needs microliters of a sample to do this.
In terms of microfabrication, the basic building block of these devices is silicon and every process starts with lithography followed by thin film deposition. etching which could be done Isotropically and anisotropically. Etching has many techniques in order to create a preferable undercut feature. There is more to microfabrication techniques but this are some useful basics of BioMems that could give you an idea of the subject.