3D Printed Materials Open the Way to Advanced Soft Robotics and Wearables

Penn State University researchers unveil 3D-printed material that could transform wearable devices

This new material, presented in a recent publication in the journal Advanced Materials, combines softness and stretchability with high electrical conductivity, overcoming key limitations of existing production methods.

A team led by corresponding author Tao Zhou, an assistant professor in Penn State’s College of Engineering, addressed the long-standing challenges of achieving both flexibility and electrical conductivity in soft materials. “People have been developing soft and stretchable conductors for almost a decade, but the conductivity is usually not very high,” Zhou noted. Traditional approaches often rely on liquid metal-based conductors, which require complex secondary activation processes that can compromise device reliability.

Flexibility and electrical conductivity in soft materials

The new approach developed by Zhou and his team eliminates the need for secondary activation. By combining liquid metal with a conductive polymer blend known as PEDOT and hydrophilic polyurethane, the researchers created a material that can self-assemble into a conductive path when printed and heated. This self-assembly process results in a highly conductive bottom layer, which is key for transmitting signals such as muscle activity and detecting stress in wearable sensors.

The top layer of material naturally oxidizes when exposed to oxygen, creating an isolated barrier that prevents signal leakage. This two-layer structure not only increases the accuracy of data collection, but also simplifies the manufacturing process, making it easier to produce wearable devices using 3D printing.

“Our method does not require any secondary activation to make the material conductive,” Zhou explained. “The material can self-assemble so that its bottom surface is highly conductive and its top surface is self-insulating.”

The Next Generation of Wearable Technology

With the ability to create complex designs using 3D printing, this material holds great promise for applications in assistive technologies for people with disabilities, where precise and reliable sensor data is crucial.

The study’s co-authors, including graduate students Salahuddin Ahmed, Marzia Momin, Jiashu Ren of the Department of Science and Technology Engineering and Mechanics, and Hyunjin Lee of the Department of Biomedical Engineering at Penn State, emphasize that it was this collaborative effort that made the breakthrough possible.

Funding for the research was provided by the National Taipei University of Technology and Penn State Collaborative Seed Grant Program, an example of global collaboration that is driving innovation in materials science and biomedical engineering.