Piezoelectric materials are used in everything from cellphones and wearables, to robotics, energy harvesting, and tactile sensors.
Piezoelectric materials come in only a few defined shapes and are made of brittle crystal and ceramic, requiring manufacture in a cleanroom. This new design method and platform 3D-prints these materials so they are not restricted by shape or size and can be custom-designed to convert movement, impact, and stress from any direction to electrical energy. By programming 3D active topology, any combination of piezoelectric coefficients can be achieved within a material, which can be used as transducers and sensors that are not only flexible and strong but also respond to pressure, vibration, and impact via electric signals that tell the location, magnitude, and direction of the impacts. Highly sensitive piezoelectric inks can be sculpted into complex 3D features with ultraviolet light. The inks contain highly concentrated piezoelectric nanocrystals bonded with UV-sensitive gels that form a solution that is printed with a high-resolution digital light 3D printer. 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.
Virginia Tech College of Engineering, Blacksburg
The team has printed and demonstrated smart materials wrapped around curved surfaces, worn on hands and fingers to convert motion, and harvest the mechanical energy. A team is making wearable devices — such as rings and shoe insoles — and is fitting them into a boxing glove to record impact forces and monitor the health of the boxer.
The technology has applications beyond consumer electronics. It can also be applied as a smart transducer that converts underwater vibration signals to electric voltages. The structure of the material is the sensor — it can monitor itself.