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Harvard Researchers Develop Conductive Ink to Embed Sensors into Soft Robotics

Picture of Anne Freier
by Anne Freier
Mar 1, 2018

Researchers from Harvard University have developed a 3D printing platform for creating soft robotic systems embedded with sensors. The team uses a technique developed in the lab of Jennifer Lewis to 3D print organic ionic liquid-based conductive ink within soft elastomer matrices. 

The present boundaries of soft robotics production could soon be expanding thanks to a team of researchers at Harvard University. In the past, members of the prestigious university had already created robots that could crawl, swim, and even grasp objects. However, until now, the devices were not able to sense or respond to the world around them.

Initially inspired by the functions of body sensory capillaries, experts at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering have devised a platform to manufacture soft robotic systems with sensors. These embedded sensors are able to deduce movement, pressure, touch, and also temperature.

Ryan Truby, a PhD graduate and first author on the ensuing research paper published in Advanced Materials, explains:

“Our research represents a foundational advance in soft robotics. Our manufacturing platform enables complex sensing motifs to be easily integrated into soft robotic systems.”

To achieve their goals, the Harvard research team had to overcome a daunting hurdle, implementing sensors–which tend to be more rigid–into soft robotic systems. And so, the team devised an organic ionic liquid-based conductive ink that can be 3D printed within soft elastomer matrices.

This technique allows the researchers to directly print liquid sensors into their soft robots. According to Michael Wehner, former postdoctoral fellow at SEAS and co-author of the paper, this development will expand the possibilities of device design and fabrication, ultimately enabling a “true closed loop control of soft robots”.

Embedding Sensors into Soft Robotics with 3D Printable Conductive Ink

The team utilizes a 3D printing technique developed in the lab headed by Jennifer Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at SEAS and a Core Faculty Member of the Wyss Institute.

Using this embedded printing method, the team is able to integrate multiple features and materials into a single soft body. The process made it possible to combine soft sensing and actuation into one integrated soft robotics system.

Integrating conductive ionic ink into the body of the actuator. (Source: Harvard)

“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. “The techniques developed in the Lewis Lab have the opportunity to revolutionize how robots are created — moving away from sequential processes and creating complex and monolithic robots with embedded sensors and actuators.”

In order to test the liquid sensors, the research team 3D printed a soft robotic gripper equipped with three soft fingers. After embedding multiple contact sensors, which allows that gripper to sense light and deep touches, they tested the device’s ability to sense inflation pressure, curvature, contact, and temperature.

In the future, the team hopes to tap machine learning to train their robots to grasp objects of varying size, shape, surface texture, and temperature.

Gripping action of robot with newly developed sensors. (Image: Advanced Materials)

Source: Harvard SEAS

License: The text of "Harvard Researchers Develop Conductive Ink to Embed Sensors into Soft Robotics" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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