Kink and Delta Self-Actuating Platinum Micro-Robot

Abstract

Catalytic micro- and nanorobots exhibit self-propulsion in the presence of chemical fuels such as glucose, hydrogen peroxide. Generally, swimmers incorporate a catalyst as a part of their structure for the decomposition of a chemical fuel. Several applications such as active drug delivery, minimally invasive surgery, and water remediation, have been envisaged. In this letter, we investigated the influence of geometric variable of catalytic microrobot to their swimming behaviors in hydrogen peroxide (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) solutions. V-shaped microrobots with various opening angles (45°, 90°, and 135°), and triangle-shaped microrobots that have similar dimensions with V-shaped microrobots, have been fabricated by focused-ion-beam etching on commercial platinum microwires. Swimming tests were performed in 15% and 30% H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solutions. We have found that V-shaped microrobot with 45° opening angle showed a superior swimming speed of 4.3 μm/s in 15% H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solution, while 90° microrobot exhibits a speed of 1.52 μm/s. The 135° V-shaped microrobot and all triangle-shaped microrobots have not shown any obvious motions in 30% H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solution. Our observation that the swimming performances of various shaped microrobots change in tandem proves the necessity of structural asymmetry in designing catalytic micro- and nanorobots.