Analytical Sciences

Particle Manipulation with External Field; From Recent Advancement to Perspectives

Akihisa MIYAGAWA* and Tetsuo OKADA**

*Department of Chemistry, Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
**Department of Chemistry, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan

Physical forces, such as dielectric, magnetic, electric, optical, and acoustic force, provide useful principles for the manipulation of particles, which are impossible or difficult with other approaches. Microparticles, including polymer particles, liquid droplets, and biological cells, can be trapped at a particular position and are also transported to arbitrary locations in an appropriate external physical field. Since the force can be externally controlled by the field strength, we can evaluate physicochemical properties of particles from the shift of the particle location. Most of the manipulation studies are conducted for particles of sub-micrometer or larger dimensions, because the force exerted on nanomaterials or molecules is so weak that their direct manipulation is generally difficult. However, the behavior, interactions, and reactions of such small substances can be indirectly evaluated by observing microparticles, on which the targets are tethered, in a physical field. We review the recent advancements in the manipulation of particles using a physical force and discuss its potentials, advantages, and limitations from fundamental and practical perspectives.

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