A highly transparent haptic device with an extremely low driving voltage based on piezoelectric PZT films on glass

Abstract

When a substrate is excited to exhibit more than 1 µm out-of-plane displacement at an ultrasonic frequency, a silent change of friction force could be clearly felt by human fingers when touch it. This is called the surface haptic feedback based on friction modulation. In this study, we designed and fabricated a highly transparent haptic device based on piezoelectric Pb(Zr,Ti)O3 (PZT) films on glass. Standing lamb waves in the vibrating plate resulting in a haptic effect was generated under sinusoidal excitation at 22.5 kHz. An extremely low unipolar voltage of 10 VPeak-to-Peak achieved a displacement of 1 µm. The displacement reached as high as 4 µm when the voltage increased to 24 VPeak-to-Peak. The average transmittance of the whole films including the PZT and the electrodes on the glass reached about 75%. The key outcome of this technology is the design of vibration modes and the effective integration of 2-µm-thick PZT film with transparent indium tin oxide (ITO) electrodes on glass.