Shape-Switching Microrobots for Medical Applications: The Influence of Shape in Drug Delivery and Locomotion

Abstract

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(ethylene glycol)diacrylate (PEGDA) layer, to achieve spontaneous and reversible folding from a planar rectangular structure. Graphene oxide (GO) or silica-coated superparamagnetic iron oxide nanoparticles 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 that 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.

Ingestible, controllable, and degradable origami robot for patching stomach wounds

“…Large efforts are still directed toward microsurgical tools that are minimally invasive, biocompatible, multifunctional, and well accepted by patients [14], [15], [16]. Due to difficulty with current treatment procedures, there is a need for miniature surgical robots that, aside from diagnosis, can potentially perform multiple medical or surgical tasks in vivo such as non-invasive transportation and deployment in a targeted location, mechanical operations on tissues or fluids, such as delivery, insertion and inflation [12], microanchoring [17] or gripping [18], removal, patching, piercing, sampling, and biodegradation. Origami robots promise to provide solutions to most of these tasks with minimal on-board electronics.…”

High-accuracy, high-speed 3D structured light imaging techniques and potential applications to intelligent robotics

“…Structured light exposure can also be used for shapeshifting soft microrobots (Fusco et al 2015) into different configurations. Huang et al (2016) demonstrated that individual microrobots can be selectively addressed by NIR light and activated for shape transformation, yielding the microrobot's ''shape'' as an extra degree of freedom for control.…”

Precise Positioning of Diamagnetically Levitated Microrobot

“…Under the mentioned conditions, microfluidic channels are seen in different structures from microrobots for control of the intended processes. Microrobotic applications can benefit from factors such as optical tweezers, thermal gradients, electrostatic forces, di-electrophoresis forces, chemical concentration differences (Ohta et al, 2012;Nelson et al, 2015). The use of microrobots in such applications is more advantageous than other applications when considering the effect on ambient conditions, the force to be applied and the precision of motion (Arai et al, 2012).…”