Piezoelectric materials are used for applications ranging from the spark igniter in barbeque grills to the transducers needed by medical ultrasound imaging.
Piezoelectric thin films on rigid substrates have limitations that come from the substrate but this thin-film piezoelectrics reduce the dependence on the substrate.Piezoelectric property will be degraded by substrate and restrict the movement.
This can be done by growing polycrystalline PZT thin films on a silicon substrate with a zinc oxide release layer, to which they added a thin layer of polyimide.
They then used acetic acid to etch away the zinc oxide, releasing the 1-micrometer thick PZT film with the polyimide layer from the silicon substrate.
The PZT film on polyimide is flexible while possessing enhanced material properties compared to the films grown on rigid substrates.
Piezoelectric devices rely on the ability of some substances like PZT to generate electric charges when physically deformed, or inversely to deform when an electric field is applied to them.
Growing high-quality PZT films, however, typically requires temperatures in excess of 650 degrees Celsius, almost 300 degrees hotter than what polyimide is able to withstand without degrading.
Most current piezoelectric device applications use bulk materials, which hampers miniaturization, precludes significant flexibility, and necessitates high-voltage operation.
This had a 45 percent increase in remanent polarization over silicon substrate controls, indicating a substantial mitigation in substrate clamping and improved performance.