What initially appears to be skeletal human hands is, in reality, a robot produced using a 3D printer. Researchers have successfully combined various curing plastics to 3D print human-like hand structures, including bones, tendons, and ligaments. This advancement opens the possibility of creating soft robots with applications such as handling fragile goods, as reported in Nature.
3D printers can tailor-produce a wide range of three-dimensional objects, from buildings and cheesecakes to human hearts. The variety of materials that can be shaped layer by layer through 3D printing is continuously expanding. However, slow-curing plastics have posed a challenge for printers. These plastics could be instrumental in creating objects that are both elastic and robust.
Scanning Instead of Scraping
Thomas Buchner from the Swiss Federal Institute of Technology in Zurich has developed a new technology that enables the use of slow-curing plastics in 3D printing. They adjusted the process of layering materials to achieve this. Typically, a UV lamp initially solidifies each layer made of viscous plastic, and a specific device scrapes over it, creating a flat surface. Only then can the next layer be added.
However, slow-curing polymers like Thiolene and epoxides are still too liquid during the scraping process, causing them to adhere to the scraping device. To overcome this obstacle, Buchner and his team replaced the scraper with a 3D laser scanner. This scanner immediately checks each printed layer for irregularities and automatically corrects them in the next layer. For example, a protruding bump in the first layer is compensated by an equally-sized notched dent in the second layer.
A Hand From the 3D Printer
According to the researchers, this development in 3D printing makes it possible to combine fast- and slow-curing plastics, which opens the door to printing a variety of new objects. These objects can include precise cavities and intricate structures, particularly relevant in robotics. Buchner and his colleagues report the direct creation of complex, high-resolution composite systems and robots.
One of their creations is the humanoid robot hands in the photo, mimicking human bones, tendons, and ligaments. The use of slow-curing Thiolene polymers made it possible to replicate ligaments. “Robots made of soft materials, such as the hand we developed, have advantages over conventional robots made of metal. Because they’re soft, there is less risk of injury when they work with humans, and they are better suited to handling fragile goods,” explains Buchner’s colleague Robert Katzschmann.
The research group will now utilize this new technology to design even more sophisticated structures and develop additional applications.