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

微技术的快速发展已经产生了微流控设备，它包括用于基于芯片的生物分析的微通道网络，以处理小体积的流体样本。为了进一步发展微型器件，对现场监测和反馈控制系统提出了很高的要求。本研究的重点是开发由小型平面表面线圈和核磁共振检测系统组成的界面分子监测系统、离子在微通道中扩散和传输的测量技术以及纳米粒子的选择性分离技术。结果摘要如下所示。利用小型平面表面线圈和核磁共振检测技术构建了水分子界面监测系统。利用该系统，观察了聚合物电解质膜(PEM)作为多孔介质时，用CPMG法测得的T2(CPMG)弛豫时间与其含水率的关系。此外，使用…在界面监测系统中，采用多脉冲梯度自旋回波法作为脉冲序列，得到了水分子的自扩散系数与膜内含水率和温度的关系。对用小尺寸平面线圈测量T2(CPMG)弛豫和自扩散系数的精度进行了评估。采用高空间分辨率的微米分辨率粒子图像测速仪，测量了微观空间中与化学反应和混合有关的速度和pH值。通过对亚微米颗粒的电泳速度和微通道内电渗速度的测量，证实了pH的变化对颗粒和微通道壁上的Zeta电位的影响。通过在微通道中产生电导率梯度，控制电渗速度和作用在颗粒上的电泳力，发展了一种亚微米颗粒的选择性分离技术。提出了一种利用声辐射力和静电力对悬浮颗粒进行连续分离的技术，实现了考虑颗粒尺寸差异的颗粒分离。较少

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