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体装置，包括用于处理小流体样本量的基于芯片的生物分析的微通道网络。为了进一步发展微型器件，迫切需要现场监测和反馈控制系统。本文主要研究了由小尺度平面表面线圈组成的界面分子监测系统和核磁共振检测系统、离子在微通道中的扩散和输运测量技术以及纳米级粒子的选择性分离技术。结果摘要如下所示。采用小尺度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CPMG法测得的T2（CPMG）弛豫时间与聚合物电解质膜（PEM）中水分含量的关系。此外，在界面监测系统中，采用…More脉冲场梯度自旋回波法作为脉冲序列，得到了PEM中水分子自扩散系数与含水率和温度之间的关系。对小尺度平面线圈测量T2（CPMG）弛豫和自扩散系数的精度进行了评价。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空间中负责化学反应和混合的速度和pH。通过测量亚微米粒子的电泳速度和微通道内的电渗透速度，证实了pH值对粒子和微通道壁的ζ电位的影响。通过在微通道中产生电导率梯度，诱导对粒子的电渗透速度和电泳力的控制，建立了亚微米粒子的选择性分离技术。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方法，实现了考虑粒径差异的悬浮颗粒分离。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