Researchers have demonstrated a new technique for making piezoelectric microelectromechanical systems (MEMS) by connecting a sample of lead zirconate titanate (PZT) piezoelectric thin films to flexible polymer substrates.

Electroded thin-film PZT on a flexible polyimide substrate.
(Credit: Tianning Liu)

The researchers grew 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-µm 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 materials are used for the transducers needed by medical ultrasound imaging. Thin-film piezoelectrics, with dimensions on the scale of micrometers or smaller, offer potential for new applications where smaller dimensions or a lower voltage operation are required.