Liquid-Loaded Piezo-Silicon Micro-Disc Oscillators for Pico-Scale Bio-Mass Sensing

• Published in: Journal of microelectromechanical systems Vol. 29; no. 5; pp. 1083 - 1086
• Main Authors: Mansoorzare, Hakhamanesh, Shahraini, Sarah, Todi, Ankesh, Azim, Nilab, Rajaraman, Swaminathan, Abdolvand, Reza
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Biomarkers; Electrodes; Frequency stability; Insertion loss; liquid mass-sensing; Liquid phases; Liquid-loaded oscillator; Liquids; Microbalances; microelectromechanical disc resonator; Micromechanical devices; Oscillators; piezoelectric transducer; Piezoelectricity; Q factors; Resonant frequency; Resonators; Sensors; Silicon; Test vehicles; Tethers; Thin films; Transistors
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2020.3008319

In this work, we report on the implementation of a closed-loop liquid-loaded resonant mass sensor as a test vehicle for the realization of highly sensitive miniaturized biomarker assays. Using thin-film piezoelectric-on-silicon (TPoS) contour-mode disc resonators that are specifically designed and optimized for liquid-phase operation, a liquid-loaded low power (~1.6 mW) oscillator at ~17 MHz is demonstrated with a single transistor. By proper placement of the electrodes and the supporting tethers, a high liquid-loaded quality factor (~380) and a low insertion loss (~19 dB) are concurrently achieved which enable the accurate frequency tracking of the potential mass microbalance. The frequency shifts due to the liquid-loading and the preliminary characterized frequency stability of the oscillator imply a minimum mass detection resolution in the picograms range. [2020-0177]