Luke A. Beardslee

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Liquid-phase operation of resonant cantilevers vibrating in an out-of-plane flexural mode has to date been limited by the considerable fluid damping and the resulting low quality factors (Q factors). To reduce fluid damping in liquids and to improve the detection limit for liquid-phase sensing applications, resonant cantilever transducers vibrating in their(More)
The influence of the beam geometry on the quality factor and resonance frequency of resonant silicon cantilever beams vibrating in their fundamental in-plane flexural mode in water has been investigated. Compared to cantilevers vibrating in their first out-of-plane flexural mode, utilizing the in-plane mode results in reduced damping and reduced mass(More)
The detection of volatile organic compounds (VOCs) in the gas phase by mass-sensitive disk microresonators is reported. The disk resonators were fabricated using a CMOS-compatible silicon micromachining process and subsequently placed in an amplifying feedback loop to sustain oscillation. Sensing of benzene, toluene, and xylene was conducted after applying(More)
A silicon-based microsystem consisting of a mass-sensitive resonant sensor and a CMOS ASIC containing feedback circuitry is demonstrated for portable sensing applications. The feedback circuitry sustains oscillation of the resonant sensor at its mechanical resonance frequency ranging between 200 and 800 kHz. The microsystem has been used for detection of(More)
Passive, LC resonators have the potential to serve as small, robust, low cost, implantable sensors to wirelessly monitor implants following orthopedic surgery. One significant barrier to using LC sensors is the influence on the sensor's resonance of the surrounding conductive high permittivity media in vivo. The surrounding media can detune the resonant(More)
We have developed a simple wireless pressure sensor that consists of only three electrically isolated components. Two conductive spirals are separated by a closed cell foam that deforms when exposed to changing pressures. This deformation changes the capacitance and thus the resonant frequency of the sensors. Prototype sensors were submerged and wirelessly(More)
A new sacrificial molding process using a single mask has been developed to fabricate ultrathin 2-dimensional membranes from several biocompatible polymeric materials. The fabrication process is similar to a sacrificial microelectromechanical systems (MEMS) process flow, where a mold is created from a material that can be coated with a biodegradable polymer(More)
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