One of the 3D-printed ‘meta-bots’ developed by UCLA engineers. Photo: Rayne Research Group/UCLA.
One of the 3D-printed ‘meta-bots’ developed by UCLA engineers. Photo: Rayne Research Group/UCLA.

Working with colleagues, a team of engineers from the University of California, Los Angeles (UCLA) has developed a new design strategy and 3D printing technique to build robots in a single step. The engineers report their advance, along with the construction and demonstration of an assortment of tiny robots that walk, maneuver and jump, in a paper in Science.

This breakthrough allows the entire mechanical and electronic systems needed to operate a robot to be manufactured all at once by a new type of 3D printing process for engineered active materials with multiple functions (also known as metamaterials). Once 3D printed, a ‘meta-bot’ will be capable of propulsion, movement, sensing and decision-making.

The printed metamaterials consist of an internal network of sensory, moving and structural elements, and can move by themselves following programmed commands. With the internal network of moving and sensing already in place, the only external component needed is a small battery to power the robot.

“We envision that this design and printing methodology of smart robotic materials will help realize a class of autonomous materials that could replace the current complex assembly process for making a robot,” said the study’s principal investigator Xiaoyu (Rayne) Zheng, an associate professor of civil and environmental engineering, and of mechanical and aerospace engineering at the UCLA Samueli School of Engineering. “With complex motions, multiple modes of sensing and programmable decision-making abilities all tightly integrated, it’s similar to a biological system with the nerves, bones and tendons working in tandem to execute controlled motions.”

Following integration with an on-board battery and controller, the engineers were able to demonstrate the fully autonomous operation of the 3D printed robots – each about the size of a fingernail. According to Zheng, who is also a member of the California NanoSystems Institute at UCLA, this methodology could lead to new designs for biomedical robots. These robots include self-steering endoscopes, and tiny swimming robots that can emit ultrasounds and navigate themselves near blood vessels to deliver drug doses at specific target sites inside the body.

These ‘meta-bots’ could also explore hazardous environments. In a collapsed building, for example, a swarm of such tiny robots, armed with integrated sensing parts, could quickly access confined spaces, assess threat levels and help rescue efforts by finding people trapped in the rubble.

Most robots, no matter their size, are typically built in a series of complex manufacturing steps that integrate their limbs with the electronic and active components. This process results in heavier weights, bulkier volumes and reduced force output compared to robots built using the new method.

The key to the UCLA-led, all-in-one method is the design and printing of piezoelectric metamaterials — a class of intricate lattice materials that can change shape and move in response to an electric field, or create electrical charge as a result of physical forces.

The use of active materials that can translate electricity into motion is not new. However, these materials generally have limits in their range of motion and distance of travel. They also need to be connected to gearbox-like transmission systems in order to achieve desired motions.

By contrast, the UCLA-developed robotic materials – each the size of a penny – are composed of intricate piezoelectric and structural elements that are designed to bend, flex, twist, rotate, expand or contract at high speeds.

The team also presented a methodology for designing these robotic materials, so users can make their own models and print the materials into a robot directly.

“This allows actuating elements to be arranged precisely throughout the robot for fast, complex and extended movements on various types of terrain,” said Huachen Cui, a UCLA postdoctoral scholar in Zheng’s Additive Manufacturing and Metamaterials Laboratory and lead author of the paper. “With the two-way piezoelectric effect, the robotic materials can also self-sense their contortions, detect obstacles via echoes and ultrasound emissions, as well as respond to external stimuli through a feedback control loop that determines how the robots move, how fast they move and toward which target they move.”

Using the new technique, the team built and demonstrated three ‘meta-bots’ with different capabilities. One robot could navigate around S-shaped corners and randomly placed obstacles, another could escape in response to a contact impact, while the third robot could walk over rough terrain and even make small jumps.

This story is adapted from material from UCLA, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.