Researchers Develop 3D Printed Smart Hydrogel That Can Walk Underwater and Pick Up Objects

Pairing 3D printing with smart technology has led to some amazing innovations, such as metal parts that can track the performance of machines, windows that can keep your car cool in the sun, and ink that can change color and shape. Now, researchers from Rutgers University-New Brunswick have developed a 3D printed smart gel that is able to grab objects, move them, and even walk underwater.

Obviously, this new innovation from Rutgers, which has some experience with unique hydrogels, has all kinds of applications in the soft robotics and biomedical fields, among others. For example, the 3D printed smart gel could be the first step in creating artificial hearts, stomachs, and other muscles, along with disease diagnosis devices and drug detection and delivery. It could even be used one day to perform inspections underwater by creating soft robots that mimic sea creatures.

Howon Lee

“Our 3D-printed smart gel has great potential in biomedical engineering because it resembles tissues in the human body that also contain lots of water and are very soft. It can be used for many different types of underwater devices that mimic aquatic life like the octopus,” said Howon Lee, an assistant professor in the university’s Department of Mechanical and Aerospace Engineering.

Lee is also the senior author of a new study, titled “Soft Robotic Manipulation and Locomotion with a 3D Printed Electroactive Hydrogel,” that was recently published in ACS Applied Materials & Interfaces about this new smart technology.

Daehoon Han, a doctoral student in mechanical and aerospace engineering in the university’s School of Graduate Studies, is the lead author of the paper, and co-authors include former Rutgers undergraduate student Cindy Farino; Rutgers’ mechanical and aerospace engineering doctoral student Chen Yang; former Rutgers post-doc Tracy Scott; Rutgers’ biomedical engineering doctoral student Daniel Browe; Wonjoon Choi, an associate professor in the School of Mechanical Engineering at Korea University in Seoul; Joseph W. Freeman, an associate professor in the Rutgers Department of Biomedical Engineering; and Lee.

The abstract reads, “Electroactive hydrogels (EAH) that exhibit large deformation in response to an electric field have received great attention as a potential actuating material for soft robots and artificial muscle. However, their application has been limited due to the use of traditional two-dimensional (2D) fabrication methods. Here we present soft robotic manipulation and locomotion with 3D printed EAH microstructures. Through 3D design and precise dimensional control enabled by a digital light processing (DLP) based micro 3D printing technique, complex 3D actuations of EAH are achieved. We demonstrate soft robotic actuations including gripping and transporting an object and a bidirectional locomotion.”

Soft materials, like this new smart gel, are flexible, able to be miniaturized, and are typically less expensive to manufacture than hard materials. When compared to complex devices made of hard materials, those fabricated using soft ones are often much easier to design and control.

The Rutgers study centers around the research team’s 3D printed hydrogel that, when activated by electricity, can move around and even change shape.

Lee explained, “This study demonstrates how our 3D-printing technique can expand the design, size and versatility of this smart gel. Our microscale 3D-printing technique allowed us to create unprecedented motions.”

Hydrogels are found in all sorts of places, like diapers, contact lenses, Jell-O (makes sense given how wiggly the dessert is), and the human body. These unique materials, even though their contents are over 70% water, will remain solid.

During the team’s DLP 3D printing process, light is projected onto a solution that’s sensitive to light, which then turns into a hydrogel. The gel is then put into a salty water solution known as an electrolyte, after which motion is triggered by two thin wires that apply electricity…kind of like Frankenstein’s monster, hold the lightning.

The result is a one inch tall, vaguely human-like walking hydrogel, which Lee says can move forward, reverse course, and grab and move objects. Lee also explained that the hydrogel resembles contracting muscles, due to its high water content, soft material make-up, and the fact that it responds to electricity. The researchers can control how quickly the smart hydrogel moves by changing up its dimensions – for example, thin gel moves faster than thick. The strength of both the electric field and the salt water solution are what determines the gel’s bending movements and shape-shifting.

To see the zombie-like smart gel move for yourself, take a look at the short video below:

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[Source: Rutgers University-New Brunswick]