Abstract
Anisotropic friction generated by microstructured surfaces is crucial for performing functions such as directional locomotion and adhesion in biological systems. Hence, an epoxy-based shape memory polymer (SMP) incorporating Fe3O4 nanoparticles is used in this study to create a smart surface with oriented structures to mimic anisotropic friction and exploit human-developed controllable locomotion systems. Applying the specific properties of the epoxy-based SMP, fast switching friction can be achieved by adjusting the topography and stiffness of the microstructures on the surface. In addition, the photothermogenesis effect of Fe3O4 nanoparticles induces changes in the asymmetric topography and stiffness on the SMP surface under the irradiation of near-infrared (NIR) light, thereby inducing a rapid switching of the friction force. Furthermore, a microbot is created to demonstrate remotely controlled locomotion, such as unidirectional and round-trip movements, and braking by switching the friction force under NIR light. These results are promising for the design of new intelligent surfaces and interfaces; additionally, they may facilitate the investigation of biological structures and processes.
Highlights
Anisotropic friction is ubiquitous in nature, and asymmetric forces must generate to achieve adhesion, locomotion, and transportation [1,2,3,4,5]
Complicated physical phenomena and processes may be involved in natural anisotropic friction systems; in many cases, a typical phenomenon encountered in nature is anisotropic microstructures on surfaces that are oriented at a certain angle to the supporting layer
It has been discovered that the anisotropic friction force generated from asymmetric microstructures primarily depends on two dominant factors: the surface topography and the stiffness of the biological surface [6]
Summary
Anisotropic friction is ubiquitous in nature, and asymmetric forces must generate to achieve adhesion, locomotion, and transportation [1,2,3,4,5]. It has been discovered that the anisotropic friction force generated from asymmetric microstructures primarily depends on two dominant factors: the surface topography and the stiffness of the biological surface [6]. As one of the most effective topographies for generating anisotropic friction force, hook-like spines are ubiquitous in various plants and animals, such as wheat awn, Galium aparine, fruit of Xanthium L, filefish skin. The stiffness of the biological surface, which has not been investigated extensively previously, has recently demonstrated its discrepant self-adaption and friction force properties [9, 10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
