On-chip self-sensing function of 4x4 matrix micromachined resonating piezoelectric membranes for mass detection applications

International audienceIn this paper, we studied the dynamic behavior of micromachined piezoelectric membranes as an alternative to the QCMs biosensors. Contrary to FPW sensors that use progressive waves at the resonance, we use standing waves on our mechanical structures which allow us to obtain higher integration density. 4×4 matrixes of piezoelectric membranes use PbZr xTi1-xO3 (PZT) as piezoelectric film which geometries have been drawn by lift-off techniques. Each membrane (circular shaped, with a radius equal to 150 microns) can be individually addressed for actuation and/or sensing. Here we show that the same kind of membranes exhibit excellent self-sensing capabilities by using the direct piezoelectric effect of the PZT layer. The open-loop resonant frequencies of several membranes were measured by examining the self-induced charge on the sense electrode using a proximity electronics circuit. We simultaneously performed resonant frequencies measures by means of a dynamic optical interferometer that completely matched the electrical self-sensed resonant spectra. In this case the piezoelectric membranes were actuated in two different ways, either by using an external transducer or by using the self-actuating (reverse piezoelectric effect) capability of each membrane