Open source fiber extruder to benefit future research in hydrogels and soft robotics

Hydrogels are highly porous, hydrophilic networks of cross-linked polymers with tunable mechanical, chemical, and stimulus-response properties. Recent advances in hydrogel 3D printing have enabled the fabrication of hydrogel structures with complex 3D geometry and a wide range of applications including tissue engineering, soft robotics, and drug delivery.

Now, researchers at Carnegie Mellon University’s College of Engineering have created a commercially available, open-source fiber extruder to benefit future research in hydrogels and soft robotics.

Hydrogels start out in liquid form as monomers. This viscous liquid, which can be made of synthetic or natural materials ranging from polyester to sodium alginate, can be used as an ink for 3D printing. When hydrogels are placed in the right environment, the monomers in the liquid cross-link to form polymers, which give the hydrogel shape and allow it to trap water. However, many hydrogel inks are so soft that newly printed structures cannot support their own weight and result in lower geometric fidelity. This is a disadvantage of working with hydrogels for robotic applications.

The input integration model shows the fiber extruder being added to the hydrogel. Credit: Biohybrid and Organic Robotics Group

To solve this problem and allow hydrogels to be used in a wider variety of tasks and harsh environments, researchers designed a continuous fiber extruder, a device that reinforces hydrogels, so they don’t come apart. not easily or lose their shape when loaded. It is designed to work with common low-cost open source desktop 3D printers equipped with a FRESH printhead and extrudes fibers of various sizes and material types.

The creation of a commercially available open-source fiber extruder will benefit future hydrogel research. The team’s extruder design is relatively inexpensive at around $53, and is also compatible with many home 3D printing devices and has been successfully tested in embedded hydrogels with synthetic and natural fibers, including silk and collagen. The results published in the publication serve almost as a formula for other researchers who wish to experiment with 3D printing of fiber-embedded hydrogel.

Hydrogels can be applied to a wider variety of situations. Their unique attributes like flexibility and softness make them ideal tools for drug delivery and tissue engineering, but physical robustness opens the door to broader tasks in soft robotics.

“We are really interested in how we can use biodegradable materials in robots,” says Webster-Wood, assistant professor of mechanical engineering who founded the Biohybrid and Organic Robotics GroupOpens in new window. “These plant-based hydrogels are a really exciting direction, because we can basically grow the materials for robots and make them renewable.”

Journal reference:

  1. Wenhuan Sun, Adam Feinberg and Victoria Webster-Wood. Continuous fiber extruder for desktop 3D printers to integrated long fiber hydrogel 3D printing. MaterialX (2022). DOI: 10.1016/j.ohx.2022.e00297.

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