A team of Harvard bioengineers may hold the key to a new generation of soft microrobots. Long touted as the future of fields like microsurgery and endoscopy, soft robots at the microscale have traditionally been limited by an inability to actuate more than one type of movement. This research effort has developed a manufacturing technique that eliminates this challenge, giving millimeter-sized robots 18 degrees of freedom. The integrated fabrication method was recently put on display when the group used it to create a tiny robot in the shape of the equally diminutive Australian peacock spider. The abilities demonstrated by the spider-bot raise intriguing questions about the medical utility of the technology going forward.
Three Techniques, One New Process
Underpinning the robot’s controllable dynamism are three distinct manufacturing methods. First, the team used soft lithography to compile 12 layers of silicone that give the robot substance. Indeed, the fabrication method is monolithic, with silicone the sole constituent. Next, using laser micromachining, each layer is cut to the exact shape of the spider cross-section it represents. Finally, a method called injection-induced self-folding forces these layers to fold themselves into their ultimate shape. A system of hollow, microfluidic channels left intentionally during the first two phases is injected with a resin and pressurized to produce this effect. Once the resin cures, the microrobot is “stuck” in its spiderlike form.
This system of actuation by pressurization, dubbed Microfluidic Origami for Reconfigurable Pneumatic/Hydraulic (MORPH) by the researchers, is also what allows movement. Another set of hollow chambers, left empty initially, can be used to colorize the robot or cause its limbs to move. This particular soft microrobot owes both its unprecedented flexibility and its good looks to injection-induced self-folding.
Spider Surgery?
While rigid, mobile microrobots already exist at this scale, they’re not often candidates for use in endoscopic or surgical procedures because of the potential for incidental, internal damage. The research team hopes their work might bring robot-assisted medicine to a higher proportion of applications.While the functionality of soft robots still lags that of their rigid counterparts, this repeatable monolithic process is an important step toward bridging that gap. The MORPH approach serves as a critical building block, one on which future iterations of soft robots might be built to serve.
For more on how the field of microrobotics is revolutionizing the way we think about medicine, check out this video.