Researchers at Pitt are exploring the use of piezoelectric materials, specifically lead zirconium titanate (PZT), as a novel approach for touchpad design and touch detection. The key focus is on three specific modes of utilizing the piezoelectric property: transverse mode, longitudinal mode, and transverse shear mode.
Description
In the transverse mode design, the piezoelectric material is placed between two electrodes. When a force is applied to the touchpad surface, it creates a stress in the piezoelectric material in the transverse direction, generating a measurable voltage output that can be used to determine the touch location. The longitudinal mode design is similar, but the piezoelectric material is oriented such that the stress is applied in the longitudinal direction. The transverse shear mode utilizes the shear deformation of the piezoelectric material to produce the voltage signal.
Applications
• Touch detection technology
Advantages
Compared to traditional touchpad technologies that rely on resistive, capacitive, or optical sensing, the piezoelectric material-based touchpad offers several key advantages. First, it demonstrates higher accuracy in touch position detection, with the equilibrium moments analysis providing precise measurement of the touch location. Second, the piezoelectric touchpad has significantly lower power consumption, as it only generates a voltage signal when touched, unlike many other touch technologies that require constant power input.
Invention Readiness
This technology is at the prototype level. The prototype uses four PZT sensors placed at the corners of the touchpad, with the voltages from these sensors used to triangulate the position of the touch using a Kalman filter algorithm to reduce noise. The prototype is able to achieve an average position detection accuracy of 6.26% with a standard deviation of 5.24% in the PZT sensor size, and also demonstrates the ability to detect touch force, though the force measurement is not as accurate due to the bouncing behavior of the test objects.
IP Status
https://patents.google.com/patent/WO2025038553A1Related Publication(s)
Lifeng Qin, Yingying Sun, Qing-Ming Wang, Youliang Zhong, Ming Ou, Zhishui Jiang, & Wei Tian. (2012). Fabrication and characterization of thick-film piezoelectric lead zirconate titanate ceramic resonators by tape-casting. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 59(12), 2803–2812. https://doi.org/10.1109/tuffc.2012.2522
