We present a technique for providing remote tactile feedback to the thumb and index finger via a wristband device. This enables haptics for touch and pinch interactions in mixed reality (MR) while keeping the hand entirely free. We achieve this through a novel cross-modal stimulation, which we term visually augmented electro-tactile feedback. This consists of (1) electrically stimulating the nerves that innervate the targeted fingers using our wristband device and (2) concurrently, visually augmenting the targeted finger in MR to steer the perceived sensation to the desired location. In our psychophysics study, we found that our approach provides tactile perception akin to tapping and, even from the wrist, it is capable of delivering the sensation to the targeted fingers with about 50% of sensation occurring in the thumb and about 40% of sensation occurring in the index finger. These results on localizability are unprecedented compared to electro-tactile feedback alone or any prior work for creating sensations in the hand with devices worn on the wrist/arm. Moreover, unlike conventional electro-tactile techniques, our wristband dispenses with gel electrodes. Instead, it incorporates custom-made elastomer-based dry electrodes and a stimulation waveform designed for the electrodes, ensuring the practicality of the device beyond laboratory settings. Lastly, we evaluated the haptic realism of our approach in mixed reality and elicited qualitative feedback from users. Participants preferred our approach to a baseline vibrotactile wrist-worn device.

翻译：我们提出了一种通过腕带设备向拇指和食指提供远程触觉反馈的技术。该技术可在保持手部完全自由的同时，为混合现实（MR）中的触摸与捏合交互提供触觉反馈。我们通过一种新颖的跨模态刺激实现了这一目标，并将其称为视觉增强电触觉反馈。该技术包含两部分：（1）使用我们的腕带设备电刺激支配目标手指的神经；（2）同时在MR中对目标手指进行视觉增强，以引导感知到的触觉指向预期位置。在我们的心理物理学研究中，我们发现该方法能提供类似轻敲的触觉感知，即使从腕部刺激，也能将触觉传递至目标手指，其中约50%的触觉感知发生在拇指，约40%发生在食指。与单独使用电触觉反馈或以往任何通过在手腕/手臂佩戴设备在手上产生触觉的研究相比，这种定位效果是前所未有的。此外，与传统电触觉技术不同，我们的腕带无需使用凝胶电极，而是采用了定制化的基于弹性体的干电极以及为该电极设计的刺激波形，确保了设备在实验室环境之外的实际可用性。最后，我们在混合现实中评估了该方法在触觉真实感方面的表现，并收集了用户的定性反馈。参与者对我们的方法的偏好优于作为基线的振动触觉腕戴设备。