Browsing by Author "Qiu, Jinze"
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Item Contribution of electrostatic interaction to the image formation in 3D thermal noise imaging(2006-12) Qiu, Jinze; Florin, Ernst-LudwigThree dimensional structures are able to be imaged by scanning the volume with a nanometer-size Brownian particle. The contribution of electrostatic interaction to the image formation in thermal noise imaging was studied. The problem was simplified to one dimension by replacing the complex three-dimensional structure with a planar coverslip. A simple fluorescence experiment was designed first to calibrate the distance from the trapping center to the planar surface. Strong electrostatic repulsion between like charged surfaces was observed in the experiments at low ionic strength as expected. Further fluorescence experiments shows that minimum separation decreases as salt concentration increases. It was found that 0.01mol/l is the optimal salt concentration for the given experimental condition. Higher concentrations lead to a permanent adhesion of particles to the surface making thermal noise imaging impossible.Item New biomedical applications of near-infrared femtosecond laser ablation(2010-12) Qiu, Jinze; Milner, Thomas E.; Neev, Joseph; Teichman, Joel M.; Tunnell, James; Dunn, Andrew; Downer, Mike; Chan, Kin F.The main purpose of this research was to investigate new medical applications of femtosecond laser ablation. A near-infrared femtosecond laser was tested and proved to be able to overcome the existing limitations and outperform the conventional long-pulse lasers in the areas of human urinary calculus (kidney stone) lithotripsy and skin treatment. The two primary objectives of my research are: 1) to investigate the feasibility of using femtosecond pulsed laser radiation to ablate urinary calculus of various compositions. The laser-calculus interaction mechanism was characterized using pump probe imaging and fast flash imaging. A novel fiber delivery system was developed to transmit and focus high energy femtosecond pulses for urinary calculus lithotripsy. The successful demonstration of the femtosecond laser lithotripsy provided a promising treatment method better than the existing long-pulse laser lithotripsy in a few different aspects, including less collateral damage to surrounding tissue, small-size debris and more controlled experimental condition. 2) to investigate the depth limitation of femtosecond subsurface ablation in scattering skin sample and develop a prototype tissue optical clearing device to enhance femtosecond beam penetration for deeper subsurface cavitation production in the skin. The successful demonstration of the device has potential benefits to new femtosecond-based therapies for reshaping or removing subcutaneous tissues.