At The Johns Hopkins University in Baltimore, MD, a team working in a new area called soft robotics is developing tiny, self-folding devices that could one day be used to perform biopsies or precisely deliver drugs inside living tissue.

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Star-shaped microgrippers could one day help surgeons perform minimally invasive biopsies.
Image credit: American Chemical Society

Soft robotics is a new area of research that is attracting interest from many fields. It uses soft and deformable structures to enable robotic systems to work in uncertain and dynamic environments; for example, to grasp and manipulate unknown objects, move about in rough terrains, and – as in the case of this new study – deal with living cells inside human bodies.

Another exciting area that is applying soft materials to robotic systems is more visionary research, such as self-repairing, growing and self-replicating robots.

However, as far as medical applications are concerned, soft robotics is still very new, so much of current research concerns itself with testing new materials and looking at potential applications rather than producing devices that are ready for clinical trials.

The team behind the new study made and tested a new material by using it to make “self-folding microgrippers” that they believe could one day allow surgeons to perform minimally invasive biopsies or deliver drugs to precise locations inside the body via remote control.

The researchers report their work in the journal ACS Applied Materials & Interfaces.

The self-folding microgrippers – which look like sea stars with six arms that can fold into themselves – are made of a hydrogel that swells and shrinks in response to changes in temperature, acidity and light.

At first, the researchers – led by Prof. David Gracias of the Department of Materials Science and Engineering at Johns Hopkins – found that while the hydrogel deformed well, it was not stiff enough to grip and hold anything.

But after running several experiments and computer models, the team found if they combined the soft, swellable hydrogel with a stiff, biodegradable polymer that does not swell, they could make a self-folding, microgripper that can wrap around cells and remove them from surrounding tissue.

In a further step, the team embedded iron nanoparticles in the stiffened hydrogel structure, so it could be remotely controlled and moved around using a non-attached magnetic probe.

The advantage of such a device is that it does not require wires to power it and make it move, so it can stay small and nimble.

The following video shows how the microgrippers work:

The researchers say their new material could be used in microassembly or microengineering of soft or biological parts, or to give surgeons the ability to remotely direct where biopsies are taken.

Prof. Gracias says the microgrippers show what can be done with these new materials, and their work opens the way to a range of biodegradable, miniaturized surgical tools that can safely dissolve in the body.

Funds for the study came from the National Science Foundation and the National Institutes of Health.

The study is a good example of new robotic methods that help keep surgical interventions as minimally invasive as possible. The less that surrounding tissue is disturbed in sampling and removing tumors, the lower the risk of complications and the faster the patient recovers.

Another remarkable example of this is a study that Medical News Today reported in December 2014, where researchers have pioneered a minimally invasive, robot-assisted procedure for treating tumors deep inside the neck or head that were previously inoperable.