By Josh Perry, Editor
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Researchers from Virginia Tech (Blacksburg, Va.) developed a new method for 3-D printing piezoelectric materials that can convert movement, impact, and mechanical stress from any direction into electrical energy.

The printed flexible sheet of piezoelectric material. (Virginia Tech)

According to a report from the school, the new process expands the number of possible shapes and sizes of piezoelectric materials that can be manufactured. “The material can also be activated, providing the next generation of intelligent infrastructures and smart materials for tactile sensing, impact and vibration monitoring, energy harvesting, and other applications,” the report added.

Using 3-D printing techniques, the researchers have eliminated the need for clean rooms and expensive manufacturing processes while also allowing more control over the voltage responses to stress from any direction. Researchers claim the process can create any combination of piezoelectric coefficients in the material.

The foundation for the new process is a synthesized piezoelectric ink that is molded into a 3-D shape using UV light. The ink contains piezoelectric nanocrystals bonded with UV-sensitive gels and the researchers demonstrated the new printing process at nanoscale levels.

“The material has sensitivities five-fold higher than flexible piezoelectric polymers,” the article noted. “The stiffness and shape of the material can be tuned and produced as a thin sheet resembling a strip of gauze, or as a stiff block.”

Researchers have used the process to build smart materials wrapped around curved surfaces and worn on hands. They see the potential applications expanding into robotics, energy harvesting, and much more.

The research was recently published in Nature Materials. The abstract stated:

“Piezoelectric coefficients are constrained by the intrinsic crystal structure of the constituent material. Here we describe design and manufacturing routes to previously inaccessible classes of piezoelectric materials that have arbitrary piezoelectric coefficient tensors.

“Our scheme is based on the manipulation of electric displacement maps from families of structural cell patterns. We implement our designs by additively manufacturing free-form, perovskite-based piezoelectric nanocomposites with complex three-dimensional architectures. The resulting voltage response of the activated piezoelectric metamaterials at a given mode can be selectively suppressed, reversed or enhanced with applied stress.

“Additionally, these electromechanical metamaterials achieve high specific piezoelectric constants and tailorable flexibility using only a fraction of their parent materials. This strategy may be applied to create the next generation of intelligent infrastructure, able to perform a variety of structural and functional tasks, including simultaneous impact absorption and monitoring, three-dimensional pressure mapping and directionality detection.”