Over the last several decades, scientists endeavoured to develop machines and robots at nanoscopic scale and envisioned that that tiny artificial machines could be used to cure diseases or fabricate novel materials.1, 2 Particularly, the nano/micro-motor with the comparable size of a single cell shows great potential in the biomedical application.3, 4 Here we describe a visible/infrared light-driven swimmer based on core/shell silicon nanowire solar cell which can be fabricated by VLS process and followed by thermal diffusion doping. The silicon nanowire solar cell harvests energy efficiently from incident photon and induces the electrochemical reaction on the silicon surface. With the asymmetric distribution of the generated ions, the nanowire propels itself autonomously in solution via self-electrophoresis mechanism. Significantly, the as-prepared swimmer can be readily propelled at ultralow-intensity (3 mW/cm2) visible/near-infrared light which is desired for the biological application. Furthermore, the morphology of fracture surface plays a crucial effect on the motion behavior determined by the spatially-confined ions around the surface. Both experimental study and theoretical simulation demonstrated the detailed structure around p/n junction can dramatically change the nanomotor migration trajectory. Furthermore, due to the well-known light trapping effect inside silicon nanowire, the spectral response of the nanowire shows typical optical resonance which opens up a new dimension for controlling the light-driven nanomotor. These results imply a promising prospect for of individually light-controlled nano/micromachines.
1. G. A. Ozin, I. Manners, S. Fournier-Bidoz and A. Arsenault, Adv. Mater., 2005, 17, 3011-3018.
2. W. Wang, W. Duan, S. Ahmed, T. E. Mallouk and A. Sen, Nano Today, 2013, 8, 531-554.
3. J. Wang and W. Gao, ACS Nano, 2012, 6, 5745-5751.
4. D. Patra, S. Sengupta, W. Duan, H. Zhang, R. Pavlick and A. Sen, Nanoscale, 2013, 5, 1273-1283.