Title :
A model for piezoresistance in torsional MEMS springs
Author :
Lenci, Silvia ; Nannini, Andrea ; Pieri, Francesco
Author_Institution :
Dipt. di Ing. dell´´Inf., Univ. di Pisa, Pisa
fDate :
June 22 2008-April 25 2008
Abstract :
A piezoresistive readout method for MEMS torsional resonators is presented. To this purpose, a new theoretical model describing the piezoresistive effects on monocrystalline and polycrystalline beams, used as suspended resistors, is investigated. A square law, linking the angular displacement thetas to the resistance variation DeltaR, is derived. The theory is confirmed by ANSYS FE (finite element) simulations. When adding a feedback to an actuator, a piezoresistive sensing part can read the output signal without increasing the process complexity and represents an alternative to capacitive sensing. A measurement configuration, based on a Wheatstone bridge, as well as an implementation of this measurement scheme to silicon-germanium (SiGe) resonators are also proposed.
Keywords :
finite element analysis; micromechanical resonators; piezoresistive devices; resistors; ANSYS finite element simulations; angular displacement; monocrystalline beams; piezoresistive readout method; polycrystalline beams; resistance variation; suspended resistors; torsional MEMS springs; torsional resonators; Actuators; Finite element methods; Germanium silicon alloys; Joining processes; Micromechanical devices; Output feedback; Piezoresistance; Resistors; Silicon germanium; Springs;
Conference_Titel :
Research in Microelectronics and Electronics, 2008. PRIME 2008. Ph.D.
Conference_Location :
Istanbul
Print_ISBN :
978-1-4244-1983-8
Electronic_ISBN :
978-1-4244-1984-5
DOI :
10.1109/RME.2008.4595728
