Electrical Muscle Stimulation (EMS) has unique capabilities that can manipulate users' actions or perceptions, such as actuating user movement while walking, changing the perceived texture of food, and guiding movements for a user learning an instrument. These applications highlight the potential utility of EMS, but such benefits may be lost if users reject EMS. To investigate user acceptance of EMS, we conducted an online survey (N=101). We compared eight scenarios, six from HCI research applications and two from the sports and health domain. To gain further insights, we conducted in-depth interviews with a subset of the survey respondents (N=10). The results point to the challenges and potential of EMS regarding social and technological acceptance, showing that there is greater acceptance of applications that manipulate action than those that manipulate perception. The interviews revealed safety concerns and user expectations for the design and functionality of future EMS applications.
doi.org/10.1145/3613904.3642585
Charts are crucial in conveying information across various fields but are inaccessible to blind and low vision (BLV) people without assistive technology. Chart comprehension tools leveraging haptic feedback have been used widely but are often bulky, expensive, and static, rendering them inefficient for conveying chart data. To increase device portability, enable multitasking, and provide efficient assistance in chart comprehension, we introduce a novel system that delivers unobtrusive modulated electrotactile feedback directly to the fingertip edge. Our three-part study with twelve participants confirmed the effectiveness of this system, demonstrating that electrotactile feedback, when applied for 0.5 seconds with a 0.12-second interval, provides the most accurate position and direction recognition. Furthermore, our electrotactile device has proven valuable in assisting BLV participants in comprehending four commonly used charts: line charts, scatterplots, bar charts, and pie charts. We also delve into the implications of our findings on recognition enhancement, presentation modes, and function synergy.
doi.org/10.1145/3613904.3642546
This paper presents TacTex, a textile-based interface that provides high-resolution haptic feedback and touch-tracking capabilities. TacTex utilizes electrotactile stimulation, which has traditionally posed challenges due to limitations in textile electrode density and quantity. TacTex overcomes these challenges by employing a multi-layer woven structure that separates conductive weft and warp electrodes with non-conductive yarns. The driving system for TacTex includes a power supply, sensing board, and switch boards to enable spatial and temporal control of electrical stimuli on the textile, while simultaneously monitoring voltage changes. TacTex can stimulate a wide range of haptic effects, including static and dynamic patterns and different sensation qualities, with a resolution of $512 \times 512$ and \textcolor{black}{based on linear electrodes spaced as closely as 2mm}. We evaluate the performance of the interface with user studies and demonstrate the potential applications of TacTex interfaces in everyday textiles for adding haptic feedback.
doi.org/10.1145/3613904.3642873
Electrical Muscle Stimulation (EMS) has emerged as a key wearable haptic feedback technology capable of simulating a wide range of force feedback, such as the impact force of boxing punches, the weight of virtual objects, and the reaction force from pushing on a wall. To simulate these external forces, EMS stimulates the muscles that oppose (i.e. antagonistic to) the actual muscles that users activate, causing involuntary muscle contraction and haptic sensations that differ from real-world experiences. In this work, we propose Paired-EMS which simultaneously stimulates both the muscles that users activate and that prior EMS stimulates (i.e. antagonistic muscle pairs) to enhance the external force feedback experience. We first conducted a small formative study (n=8) to help design the stimulation intensity of muscle pairs, then conducted a user experience study to evaluate Paired-EMS vs. prior EMS approaches for both isometric and isotonic user actions. Study results (n=32) showed that Paired-EMS significantly improved realism, harmony, and entertainment (p<.05) with similar comfort (p>.36), and was overall preferred by 78% of participants (p<.01).
doi.org/10.1145/3613904.3642841