In this study, we have demonstrated in situ, all-electrical detection of Bacillus anthracis ( BA) spores using lead magnesium niobate-lead titanate/tin (PMN-PT/Sn) piezoelectric microcantilever sensors ( PEMS) fabricated from PMN-PT freestanding films and electrically insulated with methyltrimethoxysilane (MTMS) coatings on the tin surface. Antibody specific to BA spore surface antigen was immobilized on the platinum electrode of the PMN-PT layer. In phosphate-buffered saline (PBS) solution, the PMN-PT/Sn PEMS exhibited quality (Q) values ranging from 50 to 75. The detection was carried out in a closed-loop flow cell with a liquid volume of 0.8 ml and a flow rate of 1 ml min(-1). It was shown that one sensor, "PEMS-A'' ( 500 mu m long, 800 mu m wide, with a 22 mu m thick PMN-PT layer, a 20 mu m thick tin layer and a 1 +/- 0.5 x 10(-12) g Hz(-1) mass detection sensitivity) exhibited resonance frequency shifts of 2100 +/- 200, 1100 +/- 100 and 700 +/- 100 Hz at concentrations of 20 000, 2000, and 200 spores ml(-1) or 16 000, 1600, and 160 total spores, respectively. Additionally, "`PEMS-B'' ( 350 mu m long, 800 mu m wide, with an 8 mu m thick PMN-PT layer, a 6 mu m thick tin layer and a 2 +/- 1 x 10(-13) g Hz(-1) mass detection sensitivity) exhibited resonance frequency shifts of 2400 +/- 200, 1500 +/- 200, 500 +/- 150 and 200 +/- 100 Hz at concentrations of 20 000, 2000, 100, and 45 spores ml(-1) or 16 000, 1600, 80, and 36 total spores, respectively.
