UCLA researchers 3D print entire microrobots in a single pass


A team of researchers from UCLA has developed a new method of 3D printing entire robots in one go.

The approach relies on specially developed active metamaterials (multifunctional materials) that serve as both the mechanical and electronic systems that make up a robot. These metamaterials can be 3D printed to form tiny “meta-bots” that can crawl, jump, sense their surroundings, and even make decisions about what to do next based on programmed commands.

Since the internal structural, motion, and sensing components are all printed at once, all that’s needed to bring them to life is a small power bank.

“We envision that this methodology for designing and printing smart robotic materials will help realize a class of autonomous materials that could replace the current complex assembly process to make a robot,” said Xiaoyu Zheng, principal investigator of the study. “With complex movements, multiple sensing modes, and programmable decision-making capabilities, all tightly integrated, it resembles a biological system in which nerves, bones, and tendons work in tandem to execute controlled movements.”

A 3D printed meta-bot that can move, sense, and make decisions on its own. Photo via UCLA.

A new approach to building robots

The conventional robot building process usually involves a series of manufacturing steps to assemble all of the mechanical and electronic components. Since many of these components may come from different vendors, they are unlikely to fit together perfectly, resulting in heavier assemblies, unnecessarily large volumes, and suboptimal force outputs. The UCLA 3D printing method is designed to solve these problems.

The piezoelectric nature of the printed metamaterials is crucial for the success of the method. Made in the shape of a lattice, these materials can transform into geometry and move when excited by an electric field, essentially transforming electrical energy into kinetic energy.

Although the use of piezoelectric materials in robotics is not new, their traditional use tends to be limited in terms of travel distance and range of motion. Historically, they must also be used in conjunction with gearbox type systems to achieve specific movements.

On the other hand, by 3D printing piezoelectric robots, it is possible to intelligently design complex structures that precisely bend, rotate, expand and contract, all without the need for external transmission systems.

“This allows actuation elements to be precisely arranged throughout the robot for fast, complex, and extended movements over different types of terrain,” said lead author Huachen Cui. “With the bi-directional piezoelectric effect, robotic materials can also sense their contortions themselves, detect obstacles via echoes and ultrasonic emissions, as well as respond to external stimuli via a feedback control loop that determines the how robots move, how fast they move and what target they move to.

A 3D printed network of piezoelectric metamaterials.  Photo via UCLA.
A 3D printed network of piezoelectric metamaterials. Photo via UCLA.

Rise of meta-bots

Cui’s team has already used the 3D printing technique to build three meta-bots. The first can find a way around S-shaped corners and random obstacles, the second can evade contact impacts, and the third can walk and jump over rough terrain. They even managed to incorporate small onboard batteries and microcontrollers for fully autonomous operation.

The UCLA researchers envision the method eventually being applied to new designs of biomedical robots, including self-guided endoscopes and swimming robots capable of delivering drugs to specific areas of the body.

Meta-bots could also be used to explore environments with dangerous conditions such as collapsed building rubble. For example, they could sniff their way through confined spaces and find people trapped under debris, or assess threat levels where other diagnostic equipment might not be suitable.

Further details of the study can be found in the article titled ‘Design and printing of proprioceptive three-dimensional architected robotic metamaterials’.

The design freedom afforded by 3D printing makes this technology an incredibly useful tool for applications such as self-propelled robotics. Recently, researchers from Tianjin University 3D print a flexible robot capable of moving on its own. The tube-shaped robot is made of a material called liquid crystal elastomer and self-assembles when exposed to heat. The device uses cleverly programmed bending patterns to induce tension in its own body, allowing it to flip like a log.

Elsewhere, researchers from Johannes Kepler University of Linz newly 3D-printed flexible robots with built-in sensor arrays capable of stretching up to six times their original length. To minimize the environmental impact of the manufacturing process, the team used fully biodegradable materials that could be reprinted multiple times or safely disposed of at the end of their lifespan.

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Featured image shows a 3D printed meta-bot capable of moving, sensing, and making decisions on its own. Photo via UCLA.


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