Hydrogel-Based Robots Designed for Aiding Disease Prevention

Human tissues undergo a range of mechanical stimuli that can impact their ability to perform their physiological roles, such as safeguarding organs from injury. The regulated application of such stimuli to living tissues in vitro and in vivo has currently been established as key to exploring the conditions that result in disease.

Selman Sakar’s study team at EPFL has created micromachines able to mechanically trigger cells and microtissue. These tools, which are driven by cell-sized artificial muscles, can perform complicated manipulation jobs under physiological circumstances on a microscopic scale.

The tools consist of soft robotic devices and microactuators that are wirelessly triggered by laser beams. They can also add microfluidic chips, which mean they can be used to carry out combinatorial tests that require high-throughput mechanical and chemical stimulation of a range of biological samples. This study has been reported in Lab on a Chip.

Like Legos

The researchers formulated the idea after witnessing the locomotor system in action.

We wanted to create a modular system powered by the contraction of distributed actuators and the deformation of compliant mechanisms.

Selman Sakar, Study Team Lead, EPFL

Their system involves putting together different hydrogel components—as if they were Lego bricks—to create a compliant skeleton, and then forming tendon-like polymer connections between the microactuators and the skeleton. By integrating the bricks and actuators in various ways, researchers can create an assortment of complicated micromachines.

Our soft actuators contract rapidly and efficiently when activated by near-infrared light. When the entire nanoscale actuator network contracts, it tugs on the surrounding device components and powers the machinery.

Berna Ozkale, Study Lead Author, EPFL

With this technique, researchers are able to remotely trigger multiple microactuators at definite locations—a dexterous method that yields excellent results. The microactuators finish each contraction-relaxation cycle in milliseconds with large strain.

Besides its utility in major research, this technology provides practical applications as well. For example, doctors could employ these devices as miniature medical implants to mechanically excite tissue or to actuate mechanisms for the on-demand supply of biological agents.

This study has received funding from the European Research Council (ERC) under the Horizon 2020 research and innovation program (grant agreement No. 714609).

These tools, which are powered by cell-sized artificial muscles, can carry out complicated manipulation tasks under physiological conditions on a microscopic scale. (Video credit: EPFL)