Publikationen von Tim Dünte


  • Can You Ear Me? A Comparison of Different Private and Public Notification Channels for the Earlobe
    Dennis Stanke, Tim Dünte, Kerem Can Demir and Michael Rohs
    Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies - IMWUT '23
    The earlobe is a well-known location for wearing jewelry, but might also be promising for electronic output, such as presenting notifications. This work elaborates the pros and cons of different notification channels for the earlobe. Notifications on the earlobe can be private (only noticeable by the wearer) as well as public (noticeable in the immediate vicinity in a given social situation). A user study with 18 participants showed that the reaction times for the private channels (Poke, Vibration, Private Sound, Electrotactile) were on average less than 1 s with an error rate (missed notifications) of less than 1 %. Thermal Warm and Cold took significantly longer and Cold was least reliable (26 % error rate). The participants preferred Electrotactile and Vibration. Among the public channels the recognition time did not differ significantly between Sound (738 ms) and LED (828 ms), but Display took much longer (3175 ms). At 22 % the error rate of Display was highest. The participants generally felt comfortable wearing notification devices on their earlobe. The results show that the earlobe indeed is a suitable location for wearable technology, if properly miniaturized, which is possible for Electrotactile and LED. We present application scenarios and discuss design considerations. A small field study in a fitness center demonstrates the suitability of the earlobe notification concept in a sports context.
  • Colorful Electrotactile Feedback on the Wrist
    Tim Dünte, Justin Schulte, Malte Lucius and Michael Rohs
    Proceedings of the 22nd International Conference on Mobile and Ubiquitous Multimedia - MUM '23
    Providing rich feedback on small devices, like smartwatches, can be difficult. We propose colorful electrotactile feedback on the back of a smartwatch. Colorful electrotactile feedback provides private notifications, is energy efficient, and can express various sensations in different qualities. In a first study, 13 participants explored 49 different combinations of frequency and pulse width regarding the perceived “colorfulness” of electrotactile feedback. We investigated what sensations can be expressed with electrotactile feedback and which qualities of these sensations are conveyed. To describe the sensations, participants chose the best fitting terms from a list of 21 terms. The three most frequently selected terms were prickling (177), vibrating (163), and irritating (112). The three least frequently selected ones were twitching (31), tickling (29), and itching (28). In a second study with 17 participants we evaluated a reduced set of 9 sensations that we selected and refined based on the results of study 1. We evaluated these sensations regarding recognition rates and achieved recognition rates of up to 84% without prior learning. Furthermore, we investigated the acceptance of colorful electrotactilefeedbackandpresentamethodforaneasierandfaster calibration of electrotactile feedback.


  • TactileWear: A Comparison of Electrotactile and Vibrotactile Feedback on the Wrist and Ring Finger
    Dennis Stanke, Tim Dünte and Michael Rohs
    Proceedings of the 11th Nordic Conference on Human-Computer Interaction: Shaping Experiences, Shaping Society - NordiCHI '20
    Wearables are getting more and more powerful. Tasks like notifications can be delegated to smartwatches. But the output capabilities of wearables seem to be stuck at displays and vibration. Electrotactile feedback may serve as an energy-efficient alternative to standard vibration feedback. We developed prototypes of wristbands and rings and conducted two studies to compare electrotactile and vibrotactile feedback. The prototypes have either four electrodes for electrotactile feedback or four actuators for vibration feedback. In a first study we analyzed the localization characteristics of the created stimuli. The results suggest more strongly localized sensations for electrotactile feedback, compared to vibrotactile feedback, which was more diffuse. In a second study we created notification patterns for both modalities and evaluated recognition rates, verbal associations, and satisfaction. Although the recognition rates were higher with electrotactile feedback, vibrotactile feedback was judged as more comfortable and less stressful. Overall, the results show that electrotactile feedback can be a viable alternative to vibrotactile feedback for wearables, especially for notification rings.


  • MuscleIO: Muscle-Based Input and Output for Casual Notifications
    Tim Dünte, Justin Schulte, Max Pfeiffer and Michael Rohs
    Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies - IMWUT '18
    Receiving and reacting to notifications on mobile devices can be cumbersome. We propose MuscleIO, the use of electrical muscle stimulation (EMS) for notification output and electromyography (EMG) for reacting to notifications. Our approach provides a one-handed, eyes-free, and low-effort way of dealing with notifications. We built a prototype that interleaves muscle input and muscle output signals using the same electrodes. EMS and EMG alternate such that the EMG input signal is measured in the gaps of the EMS output signal, so voluntary muscle contraction is measured during muscle stimulation. Notifications are represented as EMS signals and are accepted or refused either by a directional or a time-based EMG response. A lab user study with 12 participants shows that the directional EMG response is superior to the time-based response in terms of reaction time, error rate, and user preference. Furthermore, the directional approach is the fastest and the most intuitive for users compared to a button-based smartwatch interface as a baseline.