PNIPAm-co-AAcハイドロゲルを用いた溶液中での環境応答性自走ロボットの構築
(Development of Environmentally Responsive Self-Propelling Robots in Solution Using PNIPAm-co-AAc Hydrogels)

近年，化学エネルギーを直接利用して自律駆動するロボットに関する研究が注目を集めている．溶液中で自律駆動を示す現象の代表例として，自走液滴が挙げられるが，その自走原理に起因して，溶液との反応量
や，運動方向の制御が応用に向けた課題となっている．そこで本研究では，pH環境に応答して膨潤・収縮挙動を示PNIPAm-co-AAc ハイドロゲルに，自走液滴の一種である 1-ペンタノールを内包する手法を提案する．それによって，外部環境に応答したゲルの膨潤に伴い，自走液滴を放出することで，自立駆動を示すゲルロボットの構築を目指す．また、作製したゲルロボットに対して反応界面を制限する外骨格フレームを装着することで，自走方向の制御性についても検討する．

In recent years, autonomous robots that directly utilize chemical energy have attracted significant attention. Self-propelled droplets are a representative example of such systems exhibiting autonomous motion in solution. However, due to their underlying propulsion mechanisms, controlling the reaction rate with the surrounding solution and the direction of motion remain major challenges for practical applications. In this study, we propose a method to encapsulate 1-pentanol—a type of self-propelled droplet—into PNIPAm-co-AAc hydrogels, which exhibit pH-responsive swelling and deswelling behavior. By leveraging the swelling of the gel in response to the external environment to release the encapsulated 1-pentanol, we aim to construct a gel robot capable of autonomous propulsion. Furthermore, we investigate the controllability of the propulsion direction by equipping the fabricated gel robot with an exoskeleton frame that restricts the reaction interface.
 

Self-propulsion behavior of the emulsion gel robot for approximately 1 minute immediately after immersion (5× speed).

Self-propulsion behavior of the emulsion gel robot for approximately 150 seconds after stabilization (5× speed).

Self-propulsion behavior of the porous organogel robot for approximately 7 minutes (10× speed).

Self-propulsion behavior of the 1-pentanol solvent-based organogel robot for approximately 100 seconds (5× speed).

Self-propulsion behavior of the porous organogel robot with an exoskeleton (1× speed).

Self-propulsion behavior of the 1-pentanol solvent-based organogel with an exoskeleton (5× speed).