Self-deformable micro/nanomotors with organic-inorganic hybrid structures

This paper proposes a self-deformable structure consisting of tethered multiple micromotors. Pt/Au segmented microrods formed by electrodeposition were used as the micromotors. To fabricate flexible tethers, several approaches were tried including metal backbones, metallized DNA strands, and polymers stacked by layer-by-layer (LbL) self-assembly. For the metal backbones, shadowing effect of sputtering was used to deposit the backbones only on the half side of the micromotors. As the metallized DNA strands, λ-DNA strands with Au particle chain was formed. LbL self-assembled polymer bilayers was fabricated with a combination of poly(acrylic acid) (PAA) / poly(allylamine hydrochloride) (PAH) to encapsulate and tether the micromotors. The tethered structures were fabricated by removing a sacrificial Ag segments after the formation of the tethers. To evaluate the flexibility of the tethers, Brownian fluctuation of the open angle was traced. Micromotors tethered with the Au-metallized DNA strand and the cross-linked LbL polymers showed larger fluctuations (> 30°), whereas no fluctuation was observed with micromotors tethered with Au backbones. Furthermore, the close-to-open motion was observed with the LbL self-assembled polymer tethers.