Engineers at MIT have devised an ingenious new way to produce artificial muscles for soft robots that can flex in more than one direction, similar to the complex muscles in the human body.
The team leveraged 3D printing and muscle cells derived from humans and mice to grow an artificial structure that pulls concentrically and radially, similar to how the human iris dilates and constricts the pupil.
The researchers are calling this method 'stamping,' because it involves 3D printing a stamp patterned with microscopic grooves only large enough to each house an individual cell. Interestingly, it was inspired by the way Jell-O molds shape gelatinous desserts.
Next, they pressed the stamp into a hydrogel – a synthetic equivalent of biological tissue that provided a flexible, water-containing matrix for real cells.
These hydrogel-laden grooves were then seeded with real muscle cells that were genetically engineered to respond to light. They grew along these grooves into fibers over the course of a day, and subsequently into a muscle roughly the same size as a human iris.
The researchers then stimulated this artificial muscle with pulses of light, and it contracted in multiple directions just like a real human iris.
"In this work, we wanted to show we can use this stamp approach to make a ‘robot’ that can do things that previous muscle-powered robots can’t do,” explained Ritu Raman, who co-authored the paper describing this method that appeared last week in Biomaterials Science.
This could unlock new capabilities in soft robots, which operate more mechanically because they are fitted with inflexible components. "Instead of using rigid actuators that are typical in underwater robots, if we can use soft biological robots, we can navigate and be much more energy-efficient, while also being completely biodegradable and sustainable,” Raman noted.
The stamping method is notable not only because of what it enables, but also because it's cost-effective and easily accessible. The MIT team used high-end precision 3D printers at the university for this work, but Raman says similarly intricate stamps could be produced using consumer-grade printers as well. The stamps can also be cleaned and reused to create more artificial muscles.
The researchers plan to try stamping with other cell types, and look at other muscles they can replicate for a variety of robotic capabilities.
I'm keen to see how this is used to develop more advanced soft robots in the near future. Earlier this year, we saw Cornell University researchers come up with 'robot blood' – a Redox Flow Battery system that can be embedded in robots without the need for rigid structures. Between these two innovations, we're inching closer to creating robots that can squeeze into tight spots and investigate leaky undersea pipes, or conduct challenging search-and-rescue operations.
Source: MIT News
