title: In situ detection of Bacillus anthracis spores using fully submersible, self-exciting, self-sensing PMN-PT/Sn piezoelectric microcantilevers.
abstract: 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 microm long, 800 microm wide, with a 22 microm thick PMN-PT layer, a 20 microm 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 microm long, 800 microm wide, with an 8 microm thick PMN-PT layer, a 6 microm 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.
authors.affiliation: Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104, USA.
authors.forename: John-Paul
authors.initials: JP
authors.lastname: McGovern
authors.forename: Wan Y
authors.initials: WY
authors.lastname: Shih
authors.forename: Wei-Heng
authors.initials: WH
authors.lastname: Shih
mesh_terms: D000818:Animals; D000881:Anthrax / Q000517:prevention & control*; D001408:Bacillus anthracis; D015374:Biosensing Techniques; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D008855:Microscopy, Electron, Scanning; D013171:Spores, Bacterial / Q000648:ultrastructure