Additive Manufacturing Soft Robots from The 3D Printer

Related Vendors

FAULHABER Drive Systems

Taiwan Machine Tool & Accessory Builders' Association (TMBA)

Wuxi InfiMotion Technology Co., Ltd.

In robotics, additive manufacturing is increasingly being used to develop flexible, customized and more powerful devices. At Harvard University, a team of researchers has investigated 3D printing technology for flexible robots that are able to bend and deform by filling them with air.

Soft robots made from flexible, biocompatible materials are in high demand in industries ranging from healthcare to manufacturing. But precisely designing and controlling such robots for specific purposes is an ongoing challenge. What if you could 3D print a soft robot with predictable shape-changing capabilities already built in? Researchers at Harvard University have shown that this is possible. A study in Advanced Materials describes a new manufacturing method for printing robotic devices that feature long filaments with precisely placed hollow channels. When filled with air, the channels allow the device to bend and deform in predetermined ways.

The advance was led by doctoral student Jackson Wilt and former postdoctoral researcher Natalie Larson in the lab of Jennifer Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the John A. Paulson School of Engineering and Applied Sciences (SEAS). The method combines several Harvard-developed 3D printing techniques and bypasses traditional casting and molding typically used to create soft robots. “We use two materials from a single output that can be rotated to program the direction the robot bends as it inflates,” said Wilt. “This aligns with our goals of creating soft, biologically inspired robots for a variety of applications.”

Rotational Multi-Material 3D Printing

The new approach is based on an innovation from the Lewis lab, rotational multi-material 3D printing, where a nozzle allows more than one material to be printed at a time. As the machine rotates and reorients, it extrudes ink in customizable patterns. The lab has used this type of 3D printing to create soft, helical structures that act as artificial muscles and other objects. Using this general approach, the researchers created filaments from a polyurethane outer shell and an inner channel made of a polymer commonly found in hair gels called poloxamer. The filaments could be arranged in lines and in flat and raised patterns. By precisely controlling the design of the print nozzle, rotational speed and material flow rate, the researchers programmed the orientation, shape and size of each inner channel.

Simple Production, Complex Devices

Once the outer shell had solidified, the researchers flushed away the hair-like inner channel. The result: tubes with hollow channels that can be pressurized to bend in different directions and form the basis for soft devices that can expand, contract and grip. The research opens up new possibilities for the simple manufacture of complex devices. It offers an alternative to the traditional manufacturing method of soft robots, which typically involves pouring a soft material into a mold, patterning pneumatic channels on the surface and encapsulating the channels in another layer. "In this work, we don't have a mold. We print the structures, program them quickly and can adjust the actuation rapidly," Wilt said. They demonstrated their new technique by printing a floral pattern spiraling in a continuous, maze-like path. They also printed a five-digit handle with "knuckles" that bend. According to Wilt, their results show the potential to use this type of rapid manufacturing for applications ranging from surgical robotics to assistive devices for humans.

Additive manufacturing

Basic knowledge 3D printing