Piezoelectric bimorph micro-cantilever: a new gas pressure sensor

Micro-cantilevers are excellent micro-mechanical sensors. In this work, a piezoelectric bimorph cantilever was used as a wide range pressure sensor. Contrary to common cantilever sensor systems, the piezoelectric film of the bimorph cantilever acts as both a sensor and an actuator. The sensor detects the change in the resonance frequency of the micro cantilever with the piezoelectric film. The sensor works as a driven and damped oscillator. Firstly, description and optimisation of the cantilever are discussed in this paper. Secondly, experimental results are described. They show that both pressure and temperature can be measured simultaneously with a piezoelectric bimorph cantilever. I. INTRODUCTION Since the development of the atomic force microscopy, interest in micro-fabricated cantilevers has grown. Micro- machined cantilevers are excellent sensors, they are extremely sensitive and miniature, mass produced and low cost sensors. They operate by detecting changes either in resonance frequency, amplitude, Q-factor or deflection caused by either mass loading, surface stress variation, or any other changes of the cantilever's environment. In the first part of this work, we describe the vibration of a driven and damped simple cantilever and the impedance of a piezoelectric bimorph cantilever. Then, we discuss the optimisation of the piezoelectric bimorph cantilever. In the second part, we present the experimental results of pressure measurements at different temperatures obtained with a commercially available piezoelectric bimorph cantilever. We show it is possible to measure both pressure and temperature with a piezoelectric bimorph cantilever simultaneously.