Haptic Feedback Device Using 3D-Printed Flexible, Multilayered Piezoelectric Coating for In-Car Touchscreen Interface

Abstract

This study focuses on the development of a piezoelectric device capable of generating feedback vibrations to the user who manipulates it. The objective here is to explore the possibility of developing a haptic system that can replace physical buttons on the tactile screen of in-car systems. The interaction between the user and the developed device allows completing the feedback loop, where the user’s action generates an input signal that is translated and outputted by the device, and then detected and interpreted by the user’s haptic sensors and brain. An FEM (finite element model) via ANSYS multiphysics software was implemented to optimize the haptic performance of the wafer structure consisting of a BaTiO3 multilayered piezocomposite coated on a PET transparent flexible substrate. Several parameters relating to the geometric and mechanical properties of the wafer, together with those of the electrodes, are demonstrated to have significant impact on the actuation ability of the haptic device. To achieve the desired vibration effect on the human skin, the haptic system must be able to drive displacement beyond the detection threshold (~2 µm) at a frequency range of 100–700 Hz. The most optimized actuation ability is obtained when the ratio of the dimension (radius and thickness) between the piezoelectric coating and the substrate layer is equal to ~0.6. Regarding the simulation results, it is revealed that the presence of the conductive electrodes provokes a decrease in the displacement by approximately 25–30%, as the wafer structure becomes stiffer. To ensure the minimum displacement generated by the haptic device above 2 µm, the piezoelectric coating is screen-printed by two stacked layers, electrically connected in parallel. This architecture is expected to boost the displacement amplitude under the same electric field (denoted E) subjected to the single-layered coating. Accordingly, multilayered design seems to be a good alternative to enhance the haptic performance while keeping moderate values of E so as to prevent any undesired electrical breakdown of the coating. Practical characterizations confirmed that E=20 V/μm is sufficient to generate feedback vibrations (under a maximum input load of 5 N) perceived by the fingertip. This result confirms the reliability of the proposed haptic device, despite discrepancies between the predicted theory and the real measurements. Lastly, a demonstrator comprising piezoelectric buttons together with electronic command and conditioning circuits are successfully developed, offering an efficient way to create multiple sensations for the user. On the basis of empirical data acquired from several trials conducted on 20 subjects, statistical analyses together with relevant numerical indicators were implemented to better assess the performance of the developed haptic device.

Design Optimization of Printed Multi-Layered Electroactive Actuators Used for Steerable Guidewire in Micro-Invasive Surgery

“…• Whatever the thickness of the EAP layer (denoted 𝑡 𝐸𝐴𝑃 ): the smaller the substrate thickness, the higher the bending angle θ (and so is the tip deflection δ); • Both θ and δ have a similar trend, in which their maximum value attains a thickness ratio (𝑡 𝐸𝐴𝑃 ⁄ 𝑡 𝑠𝑢𝑏 ) of ~0.6. This finding is somehow coherent to that reported in the literature [68,69];…”

Integration of Flexible Touch Panels and Machine Learning: Applications and Techniques

“…Piezoelectric touch panels find extensive applications in various domains, including human-machine interaction. As shown in Figure 5a, Nguyen et al [73] fabricated a flexible, multilayered piezoelectric coating for tactile feedback in automotive touchscreen interfaces via 3D printing. Their tactile demonstrator consists of two touch-panel buttons for toggling the indicator lights on and off while providing vibrational feedback to the user.…”

“…Piezoelectric touch panels offer a novel approach to humanmachine interaction, with rapid response time as one of their key advantages. Bi et al [74] developed an ultrafast responsive [73] Copyright 2023, Multidisciplinary Digital Publishing Institute. b) Array-type piezoelectric touch panel with color-changing capabilities under different voltage levels.…”

“…a) Structure of a switch-type piezoelectric touch panel and demonstration of a vibration haptic actuator. Reproduced with permission [73]. Copyright 2023, Multidisciplinary Digital Publishing Institute.…”

The influence of thermo-electromechanical coupling on the performance of lead-free BNT-PDMS piezoelectric composites

“…Haptic technology has become popular recently in various sensor and actuator applications such as mobile phone screens, laptops, light-emitting diode (LED) screens, and different control panels [1,2]. These devices work on the sensors that sense the user's touch; the algorithms that process the data and the actuators that produce the haptic feedback make up the machine side.…”