Investigation of Temperature Dependency on the Propulsion of Disk-like Nanoswimmers

Abstract

Flight vehicles can soar around Earth via ejecting the combusted gases in the space and bio-molecular motor proteins possess the ability to walk along the tracts through hydrolyzing adenosine triphosphate (ATP) in cells. Inspired by flight vehicles and naturally occurring bio-molecular protein motors, miniaturized disk-like nanoswimmers are proposed, which are composed of three different metals: gold (Au), nickel (Ni), and platinum (Pt). The proposed nanoswimmers are fabricated via a layer-by-layer deposition method base on nano-electro-mechanical systems (NEMS) technology, whereby Pt functions as the chemical catalyst for the decomposition of hydrogen peroxide (H₂O₂) to produce oxygen (O₂) bubbles detaching from its surface, which in turn generate recoil force to thrust nanoswimmers propelling forward. Herein, bubble propulsion mechanism originating from momentum change of a Au-Ni-Pt nanoswimmer-O₂ bubble integral system is proposed to investigate the propulsion of nanoswimmers. Experiments are mainly focused on characterizing the propulsion of nanoswimmers in diluted H₂O₂ by changing the temperature of the solution. Results show that Au-Ni-Pt nanoswimmers are able to propel forward while the generated O₂ bubbles are detached from the Pt-surface. The speeds of nanoswimmers are increased with the increment of temperature varying from 7 °C to 57 °C. It is concluded that the propulsion of nanoswimmers is temperature-dependent.