Multisensor array of mass microbalances for chemical detection based on resonant piezo-layers of screen-printed PZT

Original mass-microbalance sensors for gravimetric chemical detection are presented which are based on thickness-mode piezoelectric composite resonators made by lead zirconate titanate (PZT) films screen-printed on alumina substrate. By exploiting a cheap and affordable technology, such devices easily enable to manufacture gravimetric multisensor arrays on the same substrate. This is demonstrated by the presented four-sensor array manufactured on a 25×25 mm2 substrate, which also incorporates a thermostating element to minimize thermal drift. The resonators operate around 7 MHz and have a mass sensitivity in the order of 500 Hz/μg. The operating principle and sensor structure is described, and experimental results are reported relative to the sensors covered with purposely prepared polymeric coatings and exposed to hydrocarbon vapours (toluene and hexane) and SO2.