バイオ燃料を利用した自己推進マイクロスイマー

摘要

泳動マイクロロボットには，薬剤の長期的投与や，無痛のピンポイント手術などの革新的な非侵襲医療への応用に大きな可能性がある.人体内で自律的に医療行為をおこなうロボットのアイデアも議論されており，エネルギ供給·推進機構は最重要課題である.このためには人体で供給可能な物質をエネルギ源として利用し，マイクロスケールで有効に動作する推進原理を適用すべきである.そこでこれまでにないコンセプトとして燃料電池(BFC)機構と電気浸透推進(EOP)機構を使った自己推進マイクロスイマーを提案する.BFC機構は人体に存在する生体燃料を分解することで開回路電位(OCP)を発生させ，EOP機構はOCPから生じる電気浸透流(EOF)を用いて自己推進速度を生成する.これを実証できれば，生体医用マイクロロボットの実用化に向け大きな一歩となる.%Self-propelled swimming microrobots have significant potential for medical applications. The most important technical issue is to realize microswimmers using an energy supply mechanism functioning inside the human body and a propulsion mechanism suitable for micro fluids. Our concept uses biofuel cell (BFC) and electroosmotic propulsion (EOP). The BFC mechanism has a bioanode and a biocathode, generating an open-circuit potential (OCP) by redox reactions or biofuels. The EOP mechanism has an insulating tube arranged between the electrodes. Electroosmotic flow (EOF) is generated inside the tube by the electric force from the OCP. A reaction force then propels the tube. We derived a theoretical model of the propulsion velocity.100 μm prototypes were fabricated which were comprised of an insulating SU-8 layer and two conductive SU-8 layers incorporating enzymes, using glucose and oxygen as the biofuels. "Proof-of-Concept" experiments were conducted using the prototypes. The self-propulsion in the glucose solution was observed, confirming the validity of the concept. This configuration can be used as a standalone microrobot, or as an element in a robot system.