The future of wearable technology envisions smart devices worn as close to the human skin as possible.
Activated by “soft”, flexible electronics, this kind of second skin will enable seamless interaction between wearers and their technology, enhancing the human ability to make decisions and perform tasks.
Using a hybrid 3D printing method, researchers at Harvard University have been able to unlock a new range of materials for the technology, enabling the creation of “soft electronic devices of nearly every size and shape.”
Flexible electronics in one fell swoop
Hybrid 3D Printing of Soft Electronics, detailed in the journal Advanced Materials, is a technique that combines direct ink writing (DIW) with automated pick and place (P +P) of pre-fabricated components.
The system works using a single nozzle capable of extruding TPU, silver electronic inks, and generating a soft vacuum to pick up small electronic components. For smaller parts, like LEDS, it also has a finer pin head for accurate placing.
Alex Valentine, co-author of the study, explains, “With this technique, we can print the electronic sensor directly onto the material, digitally pick-and-place electronic components, and print the conductive interconnects that complete the electronic circuitry required to ‘read’ the sensor’s data signal in one fell swoop.”
Smart sensing of temperature and movement
As a proof of concept, the team, led by Harvard Professor Jennifer Lewis and J. Daniel Berrigan of the U.S. Air Force Research Laboratory, made a flexible strain sensor that can be attached to a person’s elbow, and a footprint capable of reading the pressure points of a person’s soles.
In a further demonstration of flexibility, a 3D printed TPU sheet holding 12 LEDs is repeatedly bent into a ring shape without compromising light quality, or causing damage to the electronic tracts.
Will Boley, a postdoctoral researcher in the SEAS Lewis lab, explains, “Because the ink and substrate are 3D-printed, we have complete control over where the conductive features are patterned, and can design circuits to create soft electronic devices of nearly every size and shape.”
Wearables, medicine and robotics
A product of the Wyss Institute of Biologically Inspired Engineering, the hybrid electronic devices are expected to find a range of applications not only in smart wearables, but in healthcare and robotics too.
Speaking to Lindsay Brownell, Professor Lewis says, “We have both broadened the palette of printable electronic materials and expanded our programmable, multi-material printing platform to enable digital ‘pick-and-place’ of electronic components.”
“We believe that this is an important first step toward making customizable, wearable electronics that are lower-cost and mechanically robust.”
Moving .gif image by Beau Jackson, via the journal of Advanced Materials (supplementary information)
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Featured image: The University of Harvard’s Hybrid 3D Printing of Soft Electronics. Photo via the Wyss Institute for Biologically Inspired Engineering