American Chemical Society, ACS Applied Materials and Interfaces, 12(7), p. 6803-6811, 2015
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The effect of dynamic shape switching of hydrogel bilayers on the performance of self-folding microrobots is investigated, for navigation in body orifices and drug release on demand. Tubular microrobots are fabricated by coupling a thermoresponsive hydrogel nanocomposite with a poly(ethyleneglycol)diacrylate (PEGDA) layer, to achieve spontaneous and reversible folding from a planar rectangular structure. Graphene oxide (GO) or silica coated iron oxide superparamagnetic particles are dispersed in the thermoresponsive hydrogel matrix to provide near infrared (NIR) light sensitivity or magnetic actuation, respectively. The NIR light responsive microstructures are fabricated for triggered drug delivery while magnetic nanocomposite-based microrobots are used to analyze the role of shape in locomotion. Experimental analysis and computational simulations of tubular structures show drug release and motility can be optimized through controlled shape change. These concepts are finally applied to helical microrobots to show a possible way to achieve autonomous behavior.