Remotely Controlled Colloidal Assembly of Soft Microrobotic Artificial Muscle

Abstract

Herein, a methodology for the directed self‐assembly of untethered microactuators and soft robotic microdevices from nanoscale building blocks is presented. The building block is a multifunctional stimuli‐responsive nanoactuator that consists of a magnetized gold nanorod encapsulated by a thermoresponsive hydrogel. The metallic core serves as a photonic nanoheater that transduces thermal energy from near‐infrared (NIR) light and a magnetic nanomotor that generates motion while driven by magnetic fields. Rapid control of temperature enables collective manipulation of nanoactuators through thermocapillary flows. In addition, catalytic activity of the nanorod instantiates a chemical reaction that covalently binds amine groups displayed on the surface of the surrounding soft gel capsule. A combination of optical and magnetic excitation realizes both reversible and permanent in situ assembly of microactuators within seconds that can perform both spatiotemporally controlled muscle‐like contraction (up to 30% strain) and motion. It is demonstrated that by linking nanoactuators with rationally designed compliant microstructures, more complex devices such as micromanipulators can be both fabricated and operated remotely. Colloidal assembly of microactuators ensures homogenous distribution of materials and functionality, thus preserving high performance provided by nanotechnology at multiple scales.

Investigating Tissue Mechanics in vitro Using Untethered Soft Robotic Microdevices

“…An alternative solution is to push the printing concept to the next level. We have recently shown that the nOMAs could be assembled on-demand by harnessing thermocapillary flows (Parreira et al, 2020 ). Thus, it is conceivable that the whole machine can be manufactured in situ using direct laser writing.…”

The Role of Soft Robotic Micromachines in the Future of Medical Devices and Personalized Medicine

“…Janus particles are asymmetrical, as seen in Figure 5d, allowing for self-assembly to enable functions which are not possible for the individual components. Janus particles have potential microfluidic and biomedical applications including sensing, catalysis, imaging, and drug delivery [119]. The particles can be manipulated and guided using various methods including light, magnetism, and pH [120].…”

Reversible Design of Dynamic Assemblies at Small Scales

“…[135] The optical gradient force of a focused laser has been used to generate light traps that can assemble microparticles into welldefined micropatterns. [136][137][138][139] Optical traps were generated by creating an interfering pattern between an annular-shaped laser and a reference beam. Nearby objects were trapped inside the spiral interference pattern.…”