The aim of the project Parallel plate structures for optical modulation within MEMPHIS (http://www.smartmix-memphis.nl/) is to investigate the realization and control of micromachined plates, suspended at extremely small distance above the substrate. Such plates are basic building blocks in many applications, e.g. power sensors, optical modulation using a mechanical structure in evanescent field, electro-mechanical tuning and electrical and optical switches. With decreasing distance it becomes more and more difficult to accurately control the gap distance. Forces due to (parasitic) charging and Casimir force need to be investigated. Suspended plates will be realized at distances between tens and a few hundreds of nanometers and need to be controlled with sub-nanometer resolution.