Array adsorbent-coated lead zirconate titanate (PZT)/stainless steel cantilevers for dimethyl methylphosphonate (DMMP) detection

Piezoelectric cantilever sensors consisting of a piezoelectric layer bonded to a non-piezoelectric substrate are sensitive to minute mass changes at the cantilever tip. With simple electrical actuation and sensing, they can be easily miniaturized for array detection. We demonstrated room-temperature detection of dimethyl methylphosphonate (DMMP), a simulant of the nerve agent, sarin, using array lead zirconate titanate (PZT)/stainless steel cantilevers coated with different metal oxide adsorbents. Binding of DMMP molecules to the adsorbent surface at the cantilever tip increases the cantilever mass and decreases the cantilever resonance frequency. Detection of DMMP is achieved by monitoring the cantilever resonance frequency shift. Exposed to DMMP, a microporous-SiO2-coated cantilever exhibits a sharp resonance frequency decrease that saturates within minutes. A mesoporous-Al2O3-coated cantilever shows a sluggish resonance frequency shift that does not saturate after an hour. An uncoated PZT/stainless steel cantilever shows no resonance frequency shift when exposed to the DMMP vapor. The combination of the three vastly different DMMP adsorption behaviors on silica, alumina, and stainless steel offers a unique pattern for DMMP recognition, which was demonstrated by the present array sensing using PZT/stainless steel cantilevers. In addition, the microporous SiO2 coating can be regenerated at room temperature for repeated use and the sensor system can be easily portable.