Piezoelectric materials are little engineering marvels that can be found in everything from our phones to electric stoves due to their ability to generate an electric charge in response to applied mechanical stress. However, they have their limitations.
The highly-useful and popular materials come in just a few defined shapes. Also, they consist of brittle crystal and ceramic that require a clean room to manufacture.
But thanks to a novel technique by Virginia Tech on US, the material can now be 3D printed in any shape or size.
The buzz
Speaking to media persons in an interview, assistant professor of mechanical engineering, Virginia Tech and member of the macromolecules innovation institute, Xiaoyu Rayne Zheng, said, “Piezoelectric materials convert strain and stress into electric charges. We have developed a design method and printing platform to freely design the sensitivity and operational modes of piezoelectric materials.”
The process
Speaking in length about the technology, Zheng said, “By programming the 3D active topology, you can achieve pretty much any combination of piezoelectric coefficients within a material, and use them as transducers and sensors that are not only flexible and strong, but also respond to pressure, vibrations and impacts via electric signals that tell the location, magnitude and direction of the impacts within any location of these materials.”
Unlike previous piezoelectrics where the electric charge was determined by intrinsic crystals, the novel method allows users to prescribe the voltage responses to be magnified, reversed or suppressed in any direction. Zheng’s team achieved this by producing substitutes for the intrinsic crystals that mimic them while allowing for the lattice orientation to be altered.
“We have synthesized a class of highly sensitive piezoelectric inks that can be sculpted into complex three-dimensional features with ultraviolet light. The inks contain highly concentrated piezoelectric nanocrystals bonded with UV-sensitive gels, which form a solution – a milky mixture like melted crystal – that we print with a high-resolution digital light 3D printer,” Zheng said.
He added, “We can tailor the architecture to make them more flexible and use them, for instance, as energy harvesting devices, wrapping them around any arbitrary curvature. We can make them thick, and light, stiff or energy-absorbing.”
Highly sensitive
The resulting materials also have sensitivities 5-fold higher than flexible piezoelectric polymers, allowing them to be produced in a scale ranging from a thin sheet of gauze to a sturdy block. “We have a team making them into wearable devices, like rings, insoles, and fitting them into a boxing glove where we will be able to record impact forces and monitor the health of the user,” said Zheng.