Nano-rheology engineering using in-air micro-droplet technology

软凝聚材料，如液晶、凝胶、胶束和生物系统，其特点是其有组织的微观结构，以自组装的方式形成。这些材料还具有对温度和压力变化、剪切变形、电场/磁场作用等外界刺激的强烈响应的特点。近年来，利用上述软凝聚态材料实现软集成器件的制造已经进行了许多研究。本研究的目的是建立纳米流变学工程技术，观察微液滴在空气中形成并经历各种相变的动态过程。在本研究中，我们开发了一种通过微观和高速观察微颗粒碰撞来观察微垃圾化学反应的新技术。我们成功地用小化学反应器中分子的扩散来解释化学反应的过程。我们还开发了一种利用一维流体系统中直径波动的自发增长来制造一系列高信誉率50万次的液体颗粒的新技术：由细喷嘴连续产生的液体射流由压电驱动器调制其直径。通过观察流体射流的破裂现象，我们可以成功地证明射流形状的演变为我们提供了水溶液的动态力学性能，如表面张力和粘弹性。综上所述，本项目所开发的技术将成为研究纳米流体物理的有力工具。

Soft condensed materials, such as liquid crystal, gel, micelle and bio systems are characterized by its organized micro-structures, which is formed in a self assembling manner. These materials are also featured by its strong response to the outer stimulation such as the change of temperature and pressure, shear deformation, and the application of the electric/magnetic field. Recently, many investigations have been carried out to realize the fabrication of soft integrated devices by using the above soft condensed materials. The purpose of this study is to establish the nano-rheoloy engineering technique which observes the dynamic process of micro fluid droplet formed and undergoing various phase transition in the air. In the study, we developed a new technique to observe the pico-litter chemical reaction through the microscopic and high speed observation of the collision of micro particles. We succeeded in explaining the proceeding of the chemical reaction in terms of the diffusion of molecules in small chemical reactors.We have also developed a new technique to fabricate a series of liquid particle with high reputation rate of 500,000 shots per our by using the spontaneous growth of the fluctuation in diameter in the one dimensional fluid system : a liquid jet continuously generated from a thin nozzle is modulated in its diameter by a piezo-driver. By observing the break-up phenomena of the fluid jet, we could successfully show that evolution in the shape of the jet provides us of the dynamic mechanical properties of the aqueous solution, such as surface tension and visco-elasticity. In conclusion, the technique developed by us in this project would be powerful tools to investigate the nanoscopic fluid physics.