Modelling of the mechanical behaviour of a differential capacitor acceleration sensor

✍ Scribed by Wolfgang Kuehnel

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 744 KB
• Volume: 48
• Category: Article
• ISSN: 0924-4247
• DOI: 10.1016/0924-4247(94)00983-o

✦ Synopsis

A mechanical model and its mathematical solution are presented, which have been developed in order to calculate the sensitivity and frequency behaviour of an acceleration sensor. The sensor is built up as an interdigitated differential capacitor and is driven in a 'high frequency' detection circuitry with an overall electromechanical closed-loop configuration. It is fabricated using surface micromachining techniques and consists of (2 \mu \mathrm{m}) thick polysilicon beams. Due to the processes during manufacturing technology, the material contains an inherent tensile stress, such that the mechanical behaviour is not only determined by the restoring bending moments of the suspension tethers. The calculated deflection of the sensor element amounts to only (0.6 \mathrm{~nm} g^{-1}); its resonance frequency is about (21 \mathrm{kHz}). The results will be discussed and compared with the results obtained by finite-element analysis.