Christopher M. Collier

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This study was designed to determine whether there was any measurable difference in the effectiveness of bacterial plaque removal between 4 commercially available dental flosses. By means of a highly standardized and controlled in vitro experimental model technique utilizing 50 freshly extracted third molars, the possibility of intra- and inter-individual(More)
An on-chip system is presented with integrated architectures for digital microfluidic actuation and sensing. Localized actuation is brought about by a digital microfluidic multiplexer layout that overcomes the challenges of multi-microdrop interference, and complete two-dimensional motion is shown for microdrops on a 14 × 14 grid with minimized complexity(More)
A digital microfluidic architecture is introduced for micron-scale localized fluid actuation and in in-situ optical sensing. Contemporary device integration challenges related to localization and device scalability are overcome through the introduction of a bi-layered digital microfluidic multiplexer. Trinary inputs are applied through differential(More)
In this work, fundamental ultrafast transient responses are studied for optical wireless communication (OWC) detectors. It is shown that material impulse responses, associated with transient photoconductivity, and geometrical input responses, associated with transient optical power, must be considered in tandem when OWC photodetection is pursued with broad(More)
Photoconductive (PC) terahertz (THz) emitters are often limited by ohmic loss and Joule heating-as these effects can lead to thermal runaway and premature device breakdown. To address this, the proposed work introduces PC THz emitters based on textured InP materials. The enhanced surface recombination and decreased charge-carrier lifetimes of the textured(More)
A 16 × 16 digital microfluidic multiplexer is demonstrated. The device makes use of dual-phase AC activation in a bi-layered electrode structure for actuating microdrops independently. A switching arrangement is employed to localize two out-of-phase AC waveforms in one overlapped region of the two-dimensional multiplexer grid. The superimposed AC waveforms(More)
In this Letter, a spherical retro-modulator architecture is introduced for operation as a bidirectional transceiver in passive optical wireless communication links. The architecture uses spherical retroreflection to enable retroreflection with broad directionality (2π steradians), and it uses all-optical beam interaction to enable modulation on ultrafast(More)
The development and ultimate operation of a nanocomposite high-aspect-ratio photoinjection (HARP) device is presented in this work. The device makes use of a nanocomposite material as the optically active layer and the device achieves a large optical penetration depth with a high aspect ratio which provides a strong actuation force far away from the point(More)