Fully Transparent Friction-Modulation Haptic Device Based on Piezoelectric Thin Film
S. Glinsek, M.A. Mahjoub, M. Rupin, T. Schenk, N. Godard, S. Girod, J.B. Chemin, R. Leturcq, N. Valle, S. Klein, C. Chappaz, and E. Defay
Advanced Functional Materials, doi:10.1002/adfm.202003539, art. no. 2003539, 2020
Standing Lamb waves in vibrating plates enable haptic interfaces. If the out-of-plane displacement of these waves exceeds 1 mu m at frequencies above 25 kHz, a silent friction modulation can be created between a human finger and a vibrating plate. A fully transparent friction-modulation haptic device based on a piezoelectric thin film is demonstrated. The antisymmetric Lamb mode induced at 73 kHz allows for a functional performance that fulfills all conditions for practical use. Out-of-plane displacement reaches 2.9 mu m when 150 V unipolar voltage is applied. The average transmittance of the whole transducer reaches 75%. The key points of this technology are: 1) a thin HfO(2)layer between lead zirconate titanate film and substrate that prevents chemical reaction between them; 2) the efficient integration of transparent indium tin oxide electrodes and solution-derived piezoelectric lead zirconate titanate thin film onto optical-grade fused silica; and 3) the use of a transparent insulating layer made of SU-8 photoresist.