MEMS Sensor Technology - Science topic

Dear Zhang Jiali

'sorry' for what?

The pull-in voltage of an electrically actuated MEMS device can be defined statically or dynamically: In the static case, the pull-in voltage is the threshold DC voltage for which the static equilibrium is stable and bounded. In the dynamic case, it is the highest DC voltage, applied as a step, for which the transient step response is bounded. In the static case the equilibrium curve has to be computed to be able to determine pull-in, whereas the dynamic the pull-in voltage is determined using a trial and error approach.

Dear Py,

There are many types of stress sensor. All pressure sensors can be used for this purpose. Sure there are mems pressure sensor. As material wise one can use resistive or capacitive sensors. Very thin sheet of semiconductors can be used as diaphragms to receive the pressure. There is also the piezoelectic materials which can be used as a pressure sensor.

Best wishes

The oscillatory response only can be seen when you have under damped scenario...you can estimate the squeeze film damping by using any damping solver simulator... alternatively you can also calculate it... The squeeze film damping varies linearly with square of the area, and inversely proportional to (gap)^3...thereafter divide it with the critical damping by the formula 2m×wn......If the ratio more than 1 it's overdamped ... you will not see and oscillatory response...if it's less than 1 then oscillatory response will be seen

Yes, SU-8 could be used as a protection coating for MEMS structures. Another possible material is parylene-C. Usually SU-8 should be spin coated on the device, whereas parylene-C can be evaporated onto the sample in a low-vacuum chamber. It is a standard polymer material used for many of the MEMS sealing applications.

Jose

Air suspension in case of passenger cars is based on four axle high sensors same like the similar application xenon headlight leveling. Could be so that in some top level cars gyro is used but as far as I'm involved there is no separate gyro.

To add on to previous answers, temperature is most commonly measured using a resistance temperature detector, or RTD. These are often composed of serpentine metal traces with a known resistance coefficient (platinum is a common choice). When the temperature of a metal increases, the resistance increases. Another method can use a semiconductor material such as polysilicon or germanium, or a semiconductor junction, which can have a much larger temperature coefficient than metal RTDs. Some of my research has actually involved using microfabricated electrodes to measure the temperature in fluids, by measuring the change in ionic mobility with temperature: check out

Hope this helps! What sort of applications are you looking at?

You can start with nano rotor/micro rotor devices..so far very few literatures are available on this topic. Nano rotor model can also be successfully used to simulate the nonlinear behavioir of various physiological molecular motors.

Hi Raghuram,

COMSOL Multiphysics is one software that involves equation based modeling. You can check those links if could help: https://goo.gl/YGJDN1 .

Also, a better and more time convenient method is to develop a Verilog-A model that characterize your whole system. Given that you already have one device described in differential equations you can model the other device also and write a complete model for the system and thus you can simulate them easily using any circuit simulation tools (e.g., Cadence Virtuoso).

Thanks a lot for reply.

I attached the comsol model file