We present Stick&Slip, a novel approach that alters friction between the fingerpad & surfaces by depositing liquid droplets that coat the fingerpad. The liquid coating modifies the finger’s coefficient of friction, allowing users to feel surfaces up to ±60% more slippery or sticky. We selected our fluids to rapidly evaporate so that the surface returns to its original friction. Unlike traditional friction-feedback, such as electroadhesion or vibration, our approach: (1) alters friction on a wide range of surfaces and geometries, making it possible to modulate nearly any non-absorbent surface; (2) scales to many objects without requiring instrumenting the target surfaces (e.g., with conductive electrode coatings or vibromotors); and (3) both in/decreases friction via a single device. We identified nine liquids and characterized their practicality by measuring evaporation rates, etc. To illustrate the applicability of our approach, we demonstrate how it enables friction in virtual/mixed-reality or, even, while using everyday objects/tools.
doi.org/10.1145/3613904.3642299
Tactile interfaces such as embossment facilitate information transfer through touch in Human-Computer Interaction (HCI). Traditional embossing methods, while enabling the creation of intricate patterns, face limitations due to mold reliance and material thickness restrictions, hindering bespoke embossment creation. In this study, we propose High-Intensity Focused Ultrasound (HIFU) as an alternative technique to produce tailored embossed designs on acrylic without the need for traditional molds. We uncover specific HIFU parameters, such as amplitude, irradiation time, and distance that directly impact essential qualities of embossment including embossment height, transparency, and line generation. Additionally, the capability of embossing without the use of molds expands the applications for quick prototyping and customization of embossed designs within HCI. Furthermore, we introduce a user interface developed to streamline the design and application of customizable tactile graphics using HIFU, aimed at non-expert users. Preliminary user studies reveal positive feedback on the interface’s intuitiveness and the quality of the HIFU embossment. Our study indicates that HIFU embossment presents a viable approach for creating embossed features in interactive systems, with the potential to offer methods for personal customization in the design of tactile materials.
doi.org/10.1145/3613904.3642890
Compliance, the degree of displacement under applied force, is pivotal in determining the material perception when touching an object. Vibrotactile actuators can be used for creating grain-based virtual compliance, but they have poor spatial resolution and a limiting rigid form factor. We propose a novel electrotactile compliance illusion that renders grains of electrical pulses on an electrode array in response to finger force changes. We demonstrate its ability to render compliance in distinct shapes through a thin, lightweight, and flexible finger-worn interface. Detailed technical parameters and the implementation of our device are provided. A controlled experiment confirms the technique can (1) create virtual compliance; (2) adjust the compliance magnitude with grain and electrode parameters; and (3) render compliance with specific shapes. In three example applications, we present how this illusion can enhance physical objects, elements in graphical user interfaces, and virtual reality experiences.
doi.org/10.1145/3613904.3641907
Finger wearable haptic devices enrich virtual reality experiences by offering haptic feedback corresponding to the virtual environment. However, despite the effectiveness of current finger wearable haptic devices in delivering haptic feedback, many are often constrained in their ability to provide force feedback across a diverse range of directions or to sustain it. Therefore, we present AirPush, a finger wearable haptic device capable of generating continuously adjustable force feedback in multiple directions using compressed air. To evaluate its usability, we conducted a technical evaluation and four user studies: (1) we obtained the user's perceptual thresholds of angles under different directions on horizontal and vertical planes, (2) in perception studies, we found that users can identify five different magnitudes of force and eight different motion when using AirPush, and (3) using it in VR applications, we confirmed that users felt more realistic and immersed when using AirPush than the HTC VIVE Controller or AirPush with a fixed nozzle.
doi.org/10.1145/3613904.3642536
Tactile technologies are important for novel user experiences. Among several tactile submodalities, cold sensation is essential for realistically portraying materials and environments. However, current cold presentations such as Peltier devices face challenges like low energy efficiency and the need for complicated equipment. To address these, we suggest leveraging alcohol's endothermic property during evaporation. Our prototype, a wristwatch wearable with a fan, capitalizes on alcohol's high volatility by absorbing ambient heat upon evaporation. The device further enhances the cooling effect by circulating air around the skin. This approach simplifies the setup required for cooling technologies and is more energy-efficient than Peltier-based systems. We also integrated perfume, which is a mixture of alcohol and scent substance, and presented a unique cooling and scent experience. The use of alcohol as a cooling method was not considered conventional, but social changes after COVID-19 made it easy to obtain a tiny amount of alcohol.
doi.org/10.1145/3613904.3642113