With embedded sensors, soft robotics can now react to sensory experiences

Harvard researchers have developed a platform for creating soft robots with embedded sensors that can sense movement, pressure, touch, and temperature. Image courtesy of Ryan L. Truby /Harvard University.

Today’s robots can crawl, swim, grasp delicate objects and even assist a beating heart. However, these robots are limited in their ability to react to real world situations.

It is because of this limitation that a group of researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering have created a platform that enables robots to sense movement, pressure, touch and temperature.

Inspired by our bodies’ sensory capabilities the team designed the platform using embedded sensors in soft robotics.

“Our manufacturing platform enables complex sensing motifs to be easily integrated into soft robotic systems,” says Ryan Truby, first author of the paper and recent Ph.D. graduate at SEAS.

For the most part, engineers have struggled to integrate sensors into soft robotics due to the fact that traditional electronics are rigid. In order to deal with this challenge, the researcher team developed an organic ionic liquid-based conductive ink that can be 3D printed within the soft elastomer matrices that comprise most soft robots.

“To date, most integrated sensor/actuator systems used in soft robotics have been quite rudimentary,” said Michael Wehner, former postdoctoral fellow at SEAS and co-author of the paper. Wehner believes the ability to 3D print ionic liquid sensors within soft robotics will open up new avenues of device design and development that will enable true closed loop control of soft robotics.

In order to develop the device, the researchers relied on an established 3D printing technique — embedded 3D printing — developed in the lab of Jennifer Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at SEAS and Core Faculty Member of the Wyss Institute.

“This new ink combined with our embedded 3D printing process allows us to combine both soft sensing and actuation in one integrated soft robotic system,” said Truby.

The team printed a soft robotic gripper with three soft fingers or actuators in order to test the effectiveness of the sensor’s ability to sense inflation pressure, curvature, contact, and temperature. They embedded multiple contact sensors, so the gripper could sense light and deep touches.

“Soft robotics are typically limited by conventional molding techniques that constrain geometry choices, or, in the case of commercial 3D printing, material selection that hampers design choices,” said Robert Wood, the Charles River Professor of Engineering and Applied Sciences at SEAS, Core Faculty Member of the Wyss Institute, and co-author of the paper.

Going forward, the team wants to harness the power of machine learning to train these devices to grasp objects of varying size, shape, surface texture, and temperature.

The research was coauthored by Abigail Grosskopf, Daniel Vogt and Sebastien Uzel. It was supported it part by through Harvard MRSEC and the Wyss Institute for Biologically Inspired Engineering and published in Advanced Materials.

www.seas.harvard.edu