DATE:

Friday, December 9, 2005

TITLE:

PMN-PT SINGLE CRYSTAL RESONATORS FOR ULTRA-SENSITIVE VAPOR SENSING (No. 93)

TIME:

3:30 PM

LOCATION:

GMCS-214

SPEAKER:

Kee Moon

Department of Mechanical Engineering

San Diego State University

ABSTRACT:

We report on an experimental comparison between PMN-PT single crystal resonators with commercially available QCM resonators showing significant superiority for new sensors over conventional quartz. Thickness acoustic mode resonators made out of PMN-PT film were fabricated for these tests. The thickness mode resonators make use of a mechanically polished PMN-PT single crystal film of thickness 30μm. The sensor response to methanol vapor condensation shows a frequency shift for the PMN-PT resonator 1000 times larger under the same environmental conditions than the commercial quartz microbalance sensor. A surface acoustic mode resonator using mechanically polished PMN-PT single crystal film of thickness 100μm was also fabricated and tested. The dimensions of the PZN-PT film sample were 5�2�0.12mm3. Thin gold interdigitated electrodes were applied on one side of the sample. A 50nm-thick gold film was evaporated on the surface and patterned using standard photolithography. This resonator sample also exhibits a resonance frequency similar to that of a commercial quartz microbalance sensor. A large frequency drop or sensitivity is again found for the PMN-PT sensors than the quartz sensors in this case. The frequency shift in the PMN-PT surface mode resonator is ~300 times larger to methanol vapor loading than in the quartz resonator.

HOST:

Jose E. Castillo