27 research outputs found
Optical Levitation of a Droplet under Linear Increase of Gravitational Acceleration
Optical levitation of a liquid droplet in gas phase was investigated under
timedependent change of the gravitational acceleration with specific flight
pattern of an airplane. Through multiple trials under linear increase of
effective gravitational acceleration, we performed the experiment of ptical
trapping of a droplet from 0.3g_0 to 0.9g_0, where g_0 = 9.8 m/s^2. During such
change of the effective gravitational acceleration, the trapping position on a
droplet with the radius of 14 μm was found to be lowered by ca. 100
μm. The essential feature of the change of the trapping position is
reproduced by a theoretical calculation under the framework of ray optics. As
far as we know, the present study is the first report on optical levitation
under time-dependent gravitational change
Sample Handling and Chemical Kinetics in an Acoustically Levitated Drop Microreactor
Accurate measurement of enzyme kinetics is an essential part of understanding the mechanisms of biochemical reactions. The typical means of studying such systems use stirred cuvettes, stopped-flow apparatus, microfluidic systems, or other small sample containers. These methods may prove to be problematic if reactants or products adsorb to or react with the container’s surface. As an alternative approach, we have developed an acoustically-levitated drop reactor eventually intended to study enzyme-catalyzed reaction kinetics related to free radical and oxidative stress chemistry. Microliter-scale droplet generation, reactant introduction, maintenance, and fluid removal are all important aspects in conducting reactions in a levitated drop. A three capillary bundle system has been developed to address these needs. We report kinetic measurements for both luminol chemiluminescence and the reaction of pyruvate with nicotinamide adenine dinucleotide, catalyzed by lactate dehydrogenase, to demonstrate the feasibility of using a levitated drop in conjunction with the developed capillary sample handling system as a microreactor
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Effects of diffraction on the measurement of the acoustic properties of liquids in thin-walled containers
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Low power acoustic harvesting of aerosols
A new acoustic device for levitation and/or concentration of aerosols and sniall liquid/solid samples (up to several millimeters in diameter) in air has been developed. The device is inexpensive, low-power, and, in its simplest embodiment, does not require accurate alignmen1 of a resonant cavity. It is constructed from a cylindrical PZT tube of outside diameter D = 19.0 mm and thickness-to-radius ratio h/a - 0.03. The lowest-order breathing mode of the tube is tuned to match a resonant mode of the interior air-filled cylindrical cavity. A high Q cavity results that can be driven efficiently. An acoustic standing wave is created in the inteirior cavity of the cylindrical shell where particle concrmtration takes place at the nodal planes of the field. It is shown that drops of water in excess of 1 mm in diameter may be levitated against the force of gravity for approxirnately 100 mW of input electrical power. The main objective of the research is to implement this lowpower device to concentrate and harvest aerosols in a flowing system. Several different cavity geonietries iwe presented for efficient collection of 1 he conaartratetl aerosols. Concentraiion factors greater than 40 iue demonstrated for particles of size 0.7 1.1 in a flow volume of 50 L/minute