Single-Metal Hybrid Micromotor

Abstract

Multimode stimuli-regulated propulsions are extremely useful for artificial micro-/nanomotors in performing specialized tasks in different microscopic environments. However, it is still a great challenge to develop a simple and efficient micro/nanosystem which can operate in complicated environments, either with fuel or without fuel. Here, we report a novel hybrid micromotor which only needs one metal with a special structure: micro-spherical shell with a hole. Since we attractively combine the inherently catalytic properties of Pt for chemical propulsion with a designed concave structure for acoustic propulsion, the micromotors can not only move rapidly in H2O2 fueled environment due to the chemical reaction between Pt and H2O2 but also can exhibit excellent acoustic propulsion in a fuel-free environment due to the non-uniform stress caused by ultrasound. In addition, the attractive group motion behavior of the motors, including aggregation, group migration, and dispersion, is easily realized by acoustic field regulation. The brand-new single-metal hybrid micromotors with a dual driving mode, flexible propulsion regulation, and efficient group motion regulation, which are essential for making micro-/nanomotors compatible with different surrounding environments, are expected to advance the field of artificial nanomachines.

Smart micro- and nanorobots for water purification

“…Electric field propulsion, achieved by combining materials with different polarizability, is similar to mag netic propulsion, including fuelfree controllable motion 57 . Acoustic fields can also actuate different micro and nanorobot designs, such as bimetallic microrods or asymmetric nanowires, owing to the pres sure exerted by acoustic radiation [58][59][60][61] (Fig. 2f).…”

Ultrasound‐trigged micro/nanorobots for biomedical applications

“…[74][75][76][77][78][79] they fabricated a platinum (Pt) micromotor with artificial concave and convex structures through a sphere-template method (Figure 3A). 48 Interestingly, the Pt micromotor can be propelled with or without US excitation (Figure 3B). When being exposed to the environment with hydrogen peroxide, Pt can catalyze the fuel to generate oxygen bubbles, actuating the Pt micromotor toward the concave side (Figure 3C); whereas when the Pt is exposed to the environment without hydrogen peroxide while with the presence of US, the Pt micromotor can move toward the convex side (Figure 3D).…”

“…Unlike other external power sources using electric and magnetic fields that are based on bulky and expensive equipment to realize strong penetration and large field coverage, US with tunable frequencies and powers can be generated through piezoelectric components. Additionally, the US itself shows extremely high energy density and low attenuation when propagating through fluid environments, paving the way for its potential application in propelling MNRs sited deeply in the tissue 13,14,17,40–52 . US displays numerous chemical and physical effects due to its periodic mechanical vibration when interacting with the medium.…”

“…In recent decades, US-propelled MNRs with distinctive structures and multifaceted functions have been widely explored. [12][13][14]17,[40][41][42][43][44][45][46][47][48][49][50][51][52] The locomotion of the MNRs also developed from marching back and forth in a onedimensional plane, moving in multiple directions in a two-dimensional (2D) plane, to rising and falling at controllable altitude in three-dimensional (3D) space. In addition to the on-demand control of locomotion velocity and navigation, by modifying the surface with bioactive substances or encapsulating therapeutic agents inside the MNRs, various biomedical applications can be achieved, like targeted drug delivery and release, toxicant detection and collection, and nano-engineering in cellular level and hard-to-reach spaces, etc.…”

“…Additionally, the US itself shows extremely high energy density and low attenuation when propagating through fluid environments, paving the way for its potential application in propelling MNRs sited deeply in the tissue. 13,14,17,[40][41][42][43][44][45][46][47][48][49][50][51][52] US displays numerous chemical and physical effects due to its periodic mechanical vibration when interacting with the medium. Cavitation effect, the best known of these physiochemical effects, involves the generation, oscillation, expansion, and collapse of microbubbles in liquid, which are accompanied by the transformation and release of acoustic energy.…”