Accelerometers, MEMS vs. ICP

When and where do we use the MEMs as opposed to the ICPs? What are the tradeoffs between the MEMs and ICP accels?

MEMS acc's are less well calibrated than the ICP units. The ICP are a more proven technology (ie more predictable reliability). Some MEMS accel's are lower accuracy, generally the cheaper ones. The cheap ones are used to add color, they accurately reflect the distribution of motion. The advantages of the MEMS accelerometers is they allow us to sample many more channels for a given level of effort (time and money). It's not very difficult to measure 40 MEMS accelerometers. It's a lot of work to measure 40 ICP accelerometers.

I would use ICPs anywhere you want to use accelerometers to measure shear wave velocity using the air piston hammers. You can do it with the MEMS, but it's harder. The Silicon Designs accelerometers are more accurate than the analog devices ones, I would say there's not much difference for our application between the Silicon Design's MEMS and the ICP accelerometers, and you should mix as required to meet the experiment needs without relying entirely on either design. Use the Analog Designs to really bulk up the channel count and to put them anywhere the transducers are at physical risk of being destroyed (eg cast in a pile tip).