FeelPen: A Haptic Stylus Displaying Multimodal Texture Feels on Touchscreens

The ever-emerging mobile market induced a blooming interest in stylus-based interactions. Most state-of-the-art styluses either provide no haptic feedback or only deliver one type of sensation, such as vibration or skin stretch. Improving these devices with display abilities of a palette of tactile feels can pave the way for rendering realistic surface sensations, resulting in more natural virtual experiences. However, integrating necessary actuators and sensors while keeping the compact form factor of a stylus for comfortable user interactions challenges their design. This situation also limits the scientific knowledge of relevant parameters for rendering compelling artificial textures for stylus-based interactions. To address these challenges, we developed FeelPen, a haptic stylus that can display multimodal texture properties (compliance, roughness, friction, and temperature) on touchscreens. We validated the texture rendering capability of our design by conducting system identification and psychophysical experiments. The experimental results confirmed that FeelPen could render a variety of modalities with wide parameter ranges necessary to create perceptually salient texture feels, making it a one-of-a-kind stylus. Our unique design and experimental results pave the way for new perspectives with stylus-based interactions on future touchscreens.

I. Introduction

Touchscreens have gained a vast space in the mobile market as part of computers, tablets, and smartphones. Being able to interact and manipulate digital content—along with engaging visual and auditory cues—provides an intuitive, efficient, and easy usage of touchscreens. Yet, commercially available ones lack vivid haptic feedback that could enable users to touch and feel the digital content; most of them only deliver confirmatory vibrations, such as buzzes and click [1]. Nonetheless, displaying richer tactile sensations could enhance the immersiveness and realism of virtual experiences [2]. When humans touch objects in the physical world, they immediately feel their roughness, softness, friction, and thermal properties; having one or more of these sensations on touchscreens would allow engaging applications. For example, perceiving the fabric of different pieces of clothing while scrolling through an online fashion store or having a simulated pen-on-paper feel while writing on a tablet would enhance the user experience.