Jelly-Like Materials for Self-Healing Robotics

Researchers have developed hydrogels that can be 3D-printed and make self-repairs at room temperature, paving the way for numerous applications.

March 24, 2022

3 Min Read

Soft materials that can heal themselves hold promise for the development of applications ranging from artificial limbs to batteries to solar panels. However, so far most of these materials have required heat to regenerate and have other challenges, limiting their use.

Now researchers at the University of Cambridge have developed novel self-healing hydrogel materials that not only can heal at room temperature, but also are biodegradable and can be fabricated using 3D printing.

The jelly-like materials also can sense strain, temperature, and humidity, making them well-suited for use in soft robotics applications such as artificial hands that are more realistic than current prosthetics.

The materials are part of ongoing work to develop soft sensing, self-healing materials for robotic hands and arms by researchers in the university’s Department of Engineering based on a project called Self-HEaling soft RObotics (SHERO) that’s been funded by the European Union.

The ultimate aim of these is materials is to be able to detect when they are damaged and then do what’s necessary to temporarily heal and continue with the task at hand without needing human interaction.


Transformative Materials

Indeed, these types of soft-sensing technologies can transform robotics, tactile interfaces, and wearable devices, among other applications, said David Hardman, a research student who is working on the project.

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“Incorporating soft sensors into robotics allows us to get a lot more information from them, like how strain on our muscles allows our brains to get information about the state of our bodies,” he said in a press statement.

However, the materials that so far have been developed aren’t very durable and also consume high amounts of energy, making them difficult to sustain.

To improve upon previous technologies, researchers worked with stretchy, gelatin-based material that’s “cheap, biodegradable and biocompatible,” Hardman said. The incorporated sensors using conductive components into the material and then tested various set-ups to see how they could work as soft sensory devices.

Salty Solution

Researchers ultimately discovered that printing sensors containing sodium chloride, or salt, instead of carbon ink resulted in a material with the desired properties. Indeed, since salt is soluble in the water-filled hydrogel, it provides a uniform channel for ionic conduction or the movement of ions necessary for electrical conductivity.

The team measured the electrical resistance of the printed materials, finding that changes in strain resulted in a highly linear response. They used this to calculate the deformations of the material, then added salt to enable sensing of stretches of more than three times the sensor’s original length. In this way, the material can be incorporated into flexible and stretchable robotic devices.

Researchers published a paper on their work in the journal NPG Asia Materials.

The team published a video showing how the material works on YouTube:

The materials have a number of qualities that make them useful for real-world applications. One is that they can heal at room temperature, which sets them apart from many previously developed self-healing materials.

Also, because they can be fabricated by 3D printing or casting and are comprised of widely available materials, they are less expensive to make than previous materials developed for the same purpose, they said. They also show long-term strength and stability without drying out, researchers added.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.

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