Microelectromechanical Systems (MEMS)
Micromachining of silicon allows for low-cost fabrication of sensors and actuators. Research on MEMS transducers has been carried out in our group from 1982 to 2003. A variety of such transducers were explored, such as condenser, piezoelectric, piezoresistive, transistor-modulating, and acousto-optic types. Also, a MEMS acoustical actuator based on the piezoelectric principle was realized.
Most successful was the silicon condenser microphone. The first description was presented by us in 1983 . Research in many laboratories was carried on in the 1980’s and 90’s [2,3]. The first commercial MEMS microphones appeared on the market in 2003. The first and main application was in mobile telephones, other applications followed. The advantage of these microphones is their low vibration sensitivity and high service temperature. In smartphones, typically two to four such transducers are used for better noise suppression and directivity. Worldwide production amounts to several billion per year.
 D. Hohm and G. M. Sessler, in Proc. of the 11th Int. Congress on Accoustics (Paris, 1983), Vol. 6, pp. 29–32.
 G. M. Sessler, J. Audio Engineer. Soc. 44, 16-22 (1996).
 G. W. Elko and K. P. Harney, Acoustics Today 5 (issue 2), 4 – 13, (2009)