Design of Wavy Ag Microwire Array for Mechanically Stable, Multimodal Vibrational Haptic Interface

• Published in: Advanced functional materials 2019-08, Vol.29 (35), p.n/a
• Main Authors: Kang, Joohoon, Park, Jae Hoon, Choi, Dong‐Soo, Kim, Do Hwan, Kim, Sang‐Youn, Cho, Jeong Ho
• Format: Article
• Language: English
• Subjects: Actuators; Arrays; beat; Controllability; Electronic devices; evaporative assembly; haptic; Haptic interfaces; Materials science; Stability; Vibration control; vibrotactile actuators; wavy silver microwires; Wearable technology
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201902703

A vibrotactile interface is an actuator device to convey haptic information intuitively from electronics to users. For the next‐generation of user‐friendly interface applications, the vibrotactile actuator is required to be vibration intensity/frequency controllable, mechanically stable, transparent, and have large scalability. Previously, although these requirements are satisfied via several approaches using a random network film of Ag wires or a mixture with conductive polymers, the random‐network‐based materials only have limited control on material density and uniformity, which in turn hinders precise control over vibration intensity and device transparency. Here, a new approach to assemble large‐scale Ag microwire arrays is demonstrated by involving an evaporative assembly method and is presented to overcome the current limitations. In particular, the 1D wavy structure derived from fractal designs promotes vibration intensity and cycling due to greater areal coverage and improved mechanical stability. Furthermore, by taking advantage of the precisely aligned microwires array, tunable multimode vibration frequencies are obtained by generating two different voltage frequencies. The large‐scale wavy Ag microwire array with precise spatial controllability will be directly adaptable as a user‐friendly interface in electronic applications like wearable devices, computer interfaces, and flexible mobile phones. Large‐scale wavy Ag microwire arrays are assembled by utilizing an evaporative assembly method for a vibrational haptic interface application. The “S‐shaped” wavy structure motivated from nature‐inspired fractal designs yields highly enhanced mechanical stability in the vibrotactile device. The well‐aligned microwire design allows for applying different voltage frequencies to generate multimodal haptic beats.