Buildings cost a lot these days. But when concrete buildings are being constructed, there’s another material that can make them less expensive: mud.

MIT researchers have developed a method to use lightly treated mud, including soil from a building site, as the “formwork” molds into which concrete is poured. The technique deploys 3D printing and can replace the more costly method of building elaborate wood formworks for concrete construction.

“What we’ve demonstrated is that we can essentially take the ground we’re standing on, or waste soil from a construction site, and transform it into accurate, highly complex, and flexible formwork for customized concrete structures,” says Sandy Curth, a PhD student in MIT’s Department of Architecture who has helped spearhead the project.

Soft robots excel in safety and adaptability, yet their lack of structural integrity and dependency on open-curve movement paths restrict their dexterity. Conventional robots, albeit faster due to sturdy locomotion mechanisms, are typically less robust to physical impact. We introduce a multi-material design and printing framework that extends classical mechanism design to soft robotics, synergizing the strengths of soft and rigid materials while mitigating their respective limitations. Using a tool-changer equipped with multiple extruders, we blend thermoplastics of varying Shore hardness into monolithic systems. Our strategy emulates joint-like structures through biomimicry to achieve terrestrial trajectory control while inheriting the resilience of soft robots. We demonstrate the framework by 3D printing a legged soft robotic system, comparing different mechanism syntheses and material combinations, along with their resulting movement patterns and speeds. The integration of electronics and encoders provides reliable closed-loop control for the robot, enabling its operation across various terrains including sand, soil, and rock environments. This cost-effective framework offers an approach for creating 3D-printed soft robots employable in real-world environments.

Soft mechanism driven robots, made via multi-material 3D printing, combine soft and rigid components for robust, adaptable locomotion. This framework balances flexibility and strength, enabling effective operation across varied terrains.

Engineering researchers at Lawrence Livermore National Laboratory (LLNL) have achieved breakthroughs in multi-material 3D printing through the power of capillary action. The LLNL team printed lattice structures with a series of custom-designed unit cells to selectively absorb fluid materials and precisely direct them into patterns – making it possible to fabricate complex structures with unprintable materials or materials with vastly different properties.

According to the researchers, the technique, featured in Advanced Materials Technologies, would help engineers design and optimize structures for properties like extreme strength-to-weight ratios, large surface areas, or precision deformation.

“By decoupling some of the printing and patterning techniques, you could achieve some complex multi-material structures, and you wouldn’t always have to be able to print the material,” said Hawi Gemeda, Materials Engineering Division (MED) staff engineer at LLNL and the paper’s lead author.

Rice University researchers have revealed novel sequence-structure-property relationships for customizing engineered living materials (ELMs), enabling more precise control over their structure and how they respond to deformation forces like stretching or compression.

The study, published in a special issue of ACS Synthetic Biology, focuses on altering protein matrices, which are the networks of proteins that provide structure to ELMs. By introducing small genetic changes, the team discovered they could make a substantial difference in how these materials behaved. These findings could open doors for advancements in tissue engineering, drug delivery and even 3D printing of living devices.

“We are engineering cells to create customizable materials with unique properties,” said Caroline Ajo-Franklin, professor of biosciences and the study’s corresponding author. “While synthetic biology has given us tools to tweak these properties, the connection between genetic sequence, material structure and behavior has been largely unexplored until now.”

Researchers at the University of Isla Nublar have used 3D printing to successfully bring a dinosaur back to life.

This unique material can behave like a fluid, flowing and deforming with minimal resistance, yet it can also instantly become rigid, acting like a solid. It’s called PAM (or Polycatenated Architected Material). Its unique structure, inspired by chain mail, features interlinked shapes forming intricate three-dimensional networks. Unlike traditional materials, which are either solid with fixed structures or granular with loose, independent particles, PAMs occupy a fascinating middle ground. When subjected to shear stress, for example, the interconnected components can slide past each other, offering little resistance, much like water or honey. However, when compressed, these same components lock together, creating a rigid structure. This transition between fluid and solid-like behavior is what makes PAMs so unique. PAMs represent a new class of matter, defying the traditional classification of materials as either solid or granular. They are a hybrid, bridging the gap between these two extremes. This dynamic behavior is achieved through the intricate design of PAMs. Researchers at Caltech create these materials using 3D printing. They begin by modeling the structures on a computer, mimicking crystal lattices but replacing the fixed particles with interconnected rings or cages. These designs are then brought to life using various materials, from polymers to metals. The resulting PAMs, often small cubes or spheres, undergo rigorous testing to understand their response to different forces. They are compressed, sheared, and twisted, revealing their unusual properties. The potential applications for PAMs are vast and varied. Their ability to absorb energy efficiently makes them ideal candidates for protective gear, such as helmets, potentially offering superior protection compared to current foam-based solutions. This same property could also be utilized in packaging and other applications requiring cushioning or stabilization. Experiments with microscale PAMs have shown that they respond to electrical charges, suggesting possibilities in biomedical devices and soft robotics. Researchers are also exploring the vast design space of PAMs, using advanced techniques like artificial intelligence to discover new configurations and functionalities. While still in its early stages, PAM research promises to revolutionize material science and engineering, opening up new possibilities for a wide range of applications.

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Tissue engineering utilizes 3D printing and bioink to grow human cells on scaffolds, creating replacements for damaged tissues like skin, cartilage, and even organs. A team of researchers led by Professor Insup Noh from Seoul National University of Science and Technology, Republic of Korea, has developed a bioink using nanocellulose derived from Kombucha SCOBY (Symbiotic Culture of Bacteria and Yeast) as the scaffold material.

The biomaterial offers a sustainable alternative to conventional options, and it can be loaded onto a hand-held “Biowork” biopen, also developed by the same team. The digital biopen allows the precise application of bioink to damaged defected areas, such as irregular cartilage and large skin wounds, paving the way for more personalized and effective in vivo tissue repair, eliminating the need for in vitro tissue engineering processes.

This paper was published in the International Journal of Biological Macromolecules on 1 December 2024.

The development of biomaterials for artificial organs and tissues is an active area of research due to increases in accidental injuries and chronic diseases, along with the entry into a super-aged society. 3D bioprinting technology, which uses cells and biomaterials to create three-dimensional artificial tissue structures, has recently gained popularity. However, commonly used hydrogel-based bioinks can cause cytotoxicity due to the chemical crosslinking agent and ultraviolet light that connect the molecular structure of photocuring 3D-printed bioink.

Dr. Song Soo-chang’s research team at the Center for Biomaterials, Korea Institute of Science and Technology (KIST), revealed the first development of poly(organophosphazene) hydrogel-based temperature-sensitive bioink that stably maintained its physical structure by temperature control only without photocuring, induced tissue regeneration, and then biodegraded in the body after a certain period of time.

Current hydrogel-based bioinks must go through a photocuring process to enhance the mechanical properties of the 3D scaffold after printing, with a high risk of adverse effects in the human body. In addition, there has been a possibility of side effects when transplanting externally cultured cells within bioink to increase the tissue regeneration effect.

A class of synthetic soft materials called liquid crystal elastomers (LCEs) can change shape in response to heat, similar to how muscles contract and relax in response to signals from the nervous system. 3D printing these materials opens new avenues to applications, ranging from soft robots and prosthetics to compression textiles.

Controlling the material’s properties requires squeezing this elastomer-forming ink through the nozzle of a 3D printer, which induces changes to the ink’s internal structure and aligns rigid building blocks known as mesogens at the molecular scale. However, achieving specific, targeted alignment, and resulting properties, in these shape-morphing materials has required extensive trial and error to fully optimize printing conditions. Until now.

In a new study, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), Princeton University, Lawrence Livermore National Laboratory, and Brookhaven National Laboratory worked together to write a playbook for printing liquid crystal elastomers with predictable, controllable alignment, and hence properties, every time.

An Oregon State University researcher has helped create a new 3D printing approach for shape-changing materials that are likened to muscles, opening the door for improved applications in robotics as well as biomedical and energy devices.

The liquid crystalline elastomer structures printed by Devin Roach of the OSU College of Engineering and collaborators can crawl, fold and snap directly after printing. The study is published in the journal Advanced Materials.

“LCEs are basically soft motors,” said Roach, assistant professor of mechanical engineering. “Since they’re soft, unlike regular motors, they work great with our inherently soft bodies. So they can be used as implantable medical devices, for example, to deliver drugs at targeted locations, as stents for procedures in target areas, or as urethral implants that help with incontinence.”