Photochemical micromotor of eccentric core in isotropic hollow shell exhibiting multimodal motion behavior

Journal Article · 21 January 2022 · Applied Materials Today

DOI: https://doi.org/10.1016/j.apmt.2022.101371 · OSTI ID:1976857

Zhang, Jianhua ^[1]; Mou, Fangzhi ^[2]; Tang, Shaowen ^[2]; Kauffman, Joshua E. ^[3]; Sen, Ayusman ^[3]; Guan, Jianguo ^[2]

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1. Wuhan University of Technology (China); Pennsylvania State University, University Park, PA (United States); OSTI
2. Wuhan University of Technology (China)
3. Pennsylvania State University, University Park, PA (United States)

Adaptive motion behavior in response to different environmental stimuli is ubiquitous in biology and enables creatures to achieve a diversity of complex tasks, but not typically observed in synthetic systems. In this report we propose a design of chemically-powered micromotors actively performing multimodal motion behaviors with the external stimulus changing. They have isotropic outer surfaces but inherent inner mass asymmetry, such as eccentric core-in-hollow shell TiO₂ (E-TiO₂) microspheres. Their motion behavior can be spontaneously transformed among random Brownian propulsion (stochastic walk), negative phototaxis (moving against incident light), and negative photogravitaxis (moving against gravity) when the light intensity, illumination direction, or fuel concentration change. At a low light intensity and/or low H₂O₂ fuel concentration, the E-TiO₂ micromotors perform directional movement away from light based on the dominated diffusiophoresis by the photocatalytic reaction over the isotropic shell. With the increase of light intensity or fuel concentration, there are more and more photons or fuels to reach the eccentric core and the contribution of the photocatalytic reaction over it to the diffusiophoresis gradually becomes dominant. In this case, the E-TiO₂ micromotors perform stochastic walks near the substrate due to their Brownian random rotational reorientations. The micromotors are single component, have low density, and can be synthesized in a large scale and at a low cost. This work will facilitate the development of multifunctional micro/nanomotors with varying behaviors and functions depending on environmental cues, e.g., enabling efficient search and delivery operations.

• Research Organization: Pennsylvania State University, University Park, PA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0020964
• OSTI ID: 1976857
• Journal Information: Applied Materials Today, Journal Name: Applied Materials Today Journal Issue: C Vol. 26; ISSN 2352-9407
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English