MONITORING AND ACTIVE CONTROL OF HEAT AND MASS TRASFER IN MICRO- AND NANOSCALE

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Rapid progress in microtechnology has yielded microfluidic devices that comprise microchannel networks for chip-based biological analyses handling small fluid sample volumes. For further development of micro devices, the in-situ monitoring and feedback control system is strongly required. The present study focused on development of monitoring system of interface molecules consisting of the small-scale planar surface coil and nuclear magnetic resonance detection system, a measurement technique of ion diffusion and transport in a microchannel and selective separation techniques of nanoscale particles. Summary of the results is shown as bellow. An interface monitoring system of water molecules was constructed by small-scale planar surface coils and nuclear magnetic resonance detection technique. Using this system, the dependence of T2(CPMG) relaxation time measured by CPMG method on water content in polymer electrolyte membrane (PEM) as a porous media was observed. In addition, using the … More pulse-field-gradient spin echo method as a pulse sequence in the interface monitoring system, the relationship between self-diffusion coefficient of water molecular and water content and temperature in the PEM was obtained. The accuracies of T2(CPMG) relaxation measurement and self-diffusion coefficient measurement using the small-scale planar surface coils were evaluated. Velocity and pH in microspace that are responsible for chemical reaction and mixing were measured by micron-resolution particle image velocimetry with a high spatial resolution. The zeta-potential of particles and microchannel wall was affected by varing pH, which was confirmed by measurement of electrophoretic velocity of submicron particles and electroosmotic velocity in a microchannel. A selective separation technique of submicron particles was developed by generating the conductivity gradient in a microchannel, inducing a control of electroosmotic velocity and an electrophoretic force acting on particles. Moreover, a continuous separation technique of suspended particles was proposed by utilizing an acoustic radiation force and an electrostatic force, which realized the particle separation taking into account size difference. Less