Wearable motion sensors created by extrusion printing

The advent of high-resolution extrusion printing — think 3D printing but with ink that conducts electricity — has enabled researchers at The University of British Columbia (UBC) to explore the potential of wearable motion sensor devices that can be integrated into clothing and equipment.

In collaboration with Drexel University and the University of Toronto, the UBC research team is exploring a high-resolution extrusion printing approach to develop tiny devices with dual functionality — electromagnetic interference (EMI) shields and a body motion sensor. Tiny and lightweight, these EMI shields can have applications in the healthcare, aerospace and automotive industries.

“Advanced or smart materials that provide electrical conductivity and flexibility are highly sought-after,” said UBC’s Dr Mohammad Arjmand. “Extrusion printing of these conductive materials will allow for macro-scale patterning, meaning we can produce different shapes or geometries, and the product will have outstanding architecture flexibility.”

Currently, manufacturing technologies of these functional materials are mostly limited to laminated and unsophisticated structures that don’t enable the integration of monitoring technologies. But UBC doctoral student Ahmadreza Ghaffarkhah explained that these printed structures can be seeded with tiny cracks in the structures to track small vibrations in their surroundings, thus resulting in highly sensitive sensors.

“These vibrations can monitor a multitude of human activities, including breathing [and] facial movements, talking as well as the contraction and relaxation of a muscle,” Ghaffarkhah said.

Previously, extrusion printing technology didn’t allow for high enough printing resolution, so it was difficult to manufacture highly precise structures. Using a two-dimensional inorganic nanomaterial called MXene, alongside a conductive polymer, the research team has now customised a conductive ink with a number of properties that make it easier to adapt into wearable technologies.

“Compared to conventional manufacturing technologies, extrusion printing offers customisation, reduction in materials waste and rapid production, while opening up numerous opportunities for wearable and smart electronics,” Arjmand said. “As extrusion printing techniques improve, it is opening the door to many unique innovations.”

With their study now published in the journal Carbon, the researchers continue to investigate additional applications for extrusion printing inks that go beyond EMI shields and wearable electronics.

Image caption: Doctoral student Ahmadreza Ghaffarkhah uses a 3D printer to create small sensors that can be integrated into clothing and equipment.

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