近年，電気を用いずに駆動する動力源として自走液滴が注目されており，ドラッグデリバリーシステム等への応用が期待されている．しかし，実用化のためには自走現象の精密な制御が不可欠である一方，現状では油滴の自走方向がランダムであり応用展開は困難である． 　そこで本研究では，未だ実現されていない自走液滴の複雑な軌道制御を目的とする．水に速やかに溶解する尿素を用いた外骨格を作製し，尿素溶解が液滴内部対流に与える影響が小さいことを確認するとともに，外骨格形状の時間変化による自走軌道の多段階変更を実現する．

In recent years, self-propelled droplets have attracted attention as power sources that operate without electricity, and their application to drug delivery systems and related technologies is expected. However, precise control of the self-propulsion phenomenon is indispensable for practical applications, while the propulsion direction of oil droplets is currently random, making practical implementation difficult.
Therefore, this study aims to achieve complex trajectory control of self-propelled droplets, which has not yet been realized. An exoskeleton composed of urea, which rapidly dissolves in water, is fabricated, and it is confirmed that the dissolution of urea has only a small effect on the internal convection of the droplet. Furthermore, multistage switching of the self-propelled trajectory is achieved through time-dependent changes in the geometry of the exoskeleton.