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Engineering Breakthrough in Softbotics

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College of Engineering
Peter Kerwin
University Communications & Marketing

The newest development in softbotics(opens in new window) will have a transformative impact on robotics, electronics and medicine. Carmel Majidi(opens in new window) has engineered a soft material with metal-like conductivity and self-healing properties that, for the first time, can support power-hungry devices.

"Softbotics is about seamlessly integrating robotics into everyday life, putting humans at the center," explained Majidi, a professor of mechanical engineering(opens in new window) at Carnegie Mellon University.

Engineers work to integrate robots into everyday life with the hope of improving mobility, health and well-being. For example, patients might one day recover from surgery at home thanks to a wearable robot monitoring aid. To integrate robots seamlessly, they need to be able to move with people, withstand damage and have electrical functionality without being encased in a hard structure.

Majidi's material, a liquid metal-filled organogel composite with high electrical conductivity, low stiffness, high stretchability and self-healing properties, is foundational to bringing these softbotics to life.

The team introduced the material in three applications: a damage resistant snail-inspired robot, a modular circuit for powering a toy car, and a reconfigurable bioelectrode for measuring muscle activity on different locations of the body.

Carmel Majidi

Carmel Majidi

The fully untethered snail robot used the self-healing conductive material on its soft exterior, which was embedded with a battery and electric motor to control motion. During the demonstration, the team severed the conductive material and watched as its speed dropped by more than 50%. Because of its self-healing properties, when the material was manually reconnected, the robot restored its electrical connection and recovered 68% of its original speed.

"This is the first soft material that can maintain a high enough electrical conductivity to support digital electronics and power-hungry devices," said Majidi. "We have demonstrated that you can actually power motors with it."

The material can also act as a modular building block for reconfigurable circuits.

"In practice there will be cases where you want to reuse and recycle these gel-like electronics into different configurations, and our toy car demonstration shows that you can do that," explained Majidi.

Initially, one piece of gel connected the toy car to a motor. When the team split that gel into three sections and connected one section to a roof-mounted LED, they were able to restore the car's connection to the motor using the two remaining sections.

"Softbotics is about seamlessly integrating robotics into everyday life, putting humans at the center." — Carmel Majidi

Lastly, the team demonstrated the material's ability to be reconfigured to obtain electromyography (EMG) readings from different locations on the body. Because of its modular design, the organogel can be refitted to measure hand activity on the anterior muscles of the forearm and to the back of the leg to measure calf activity. This opens doors to tissue-electronic interfaces like EMGs and EKGs using soft, reusable materials.

"Instead of being wired up with biomonitoring electrodes connecting you to biomeasurement hardware mounted on a cart, our gel can be used as a bioelectrode that directly interfaces with body-mounted electronics that can collect information and transmit it wirelessly," Majidi explained.

Moving forward, Majidi hopes to couple this work on artificial nervous tissue with his research on artificial muscle to build robots made entirely of soft, gel-like materials.

"It would be interesting to see soft-bodied robots used for monitoring hard to reach places — whether that be a snail that could monitor water quality, or a slug that could crawl around our houses looking for mold."

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