Flat touch interfaces, with or without screens, pervade the modern world. However, their haptic feedback is minimal, prompting much research into haptic and shape-changing display technologies which are self-contained, fast acting, and offer millimeters of displacement while only being only millimeters thick. We present a new, miniaturizable type of shape-changing display using embedded electroosmotic pumps (EEOPs). Our pumps, controlled and powered directly by applied voltage, are 1.5mm in thickness, and allow complete stackups under 5mm. Nonetheless, they can move their entire volume's worth of fluid in 1 second, and generate pressures of +/-50kPa, enough to create dynamic, millimeter-scale tactile features on a surface that can withstand typical interaction forces (<1N). These are the requisite technical ingredients to enable, for example, a pop-up keyboard on a flat smartphone. We experimentally quantify the mechanical and psychophysical performance of our displays and conclude with a set of example interfaces.
Smart shape-changing materials can be adapted to different usages, which have been leveraged for dynamic affordances and on-demand haptic feedback in HCI. However, the applicability of these materials is often bottlenecked by their complex fabrication and the challenge of programming localized and individually addressable responses. In this work, we propose a toolkit for designing and fabricating programmable morphing objects using off-the-shelf epoxies. Our method involves varying the crosslinker to epoxy resin ratio to control morphing temperatures from 40 ℃ to 90 ℃, either across different regions of a shape memory device or across devices. Functional components (e.g., conductive fabric, magnetic particles) are also incorporated with the epoxy for sensing and active reconfiguration. A toolbox of fabrication methods and a primitive design library are introduced to support design ideation and programmable morphing. Finally, we demonstrate application examples, including morphing toys, a shape-changing input device, and an active window shutter.
Despite their growing popularity, many public kiosks with touchscreens are inaccessible to blind people. Toucha11y is a working prototype that allows blind users to use existing inaccessible touchscreen kiosks independently and with little effort. Toucha11y consists of a mechanical bot that can be instrumented to an arbitrary touchscreen kiosk by a blind user and a companion app on their smartphone. The bot, once attached to a touchscreen, will recognize its content, retrieve the corresponding information from a database, and render it on the user's smartphone. As a result, a blind person can use the smartphone's built-in accessibility features to access content and make selections. The mechanical bot will detect and activate the corresponding touchscreen interface. We present the system design of Toucha11y along with a series of technical evaluations. Through a user study, we found out that Toucha11y could help blind users operate inaccessible touchscreen devices.
Soft (compliant) curvature-changing UIs provide haptic feedback through changes in softness and curvature. Different softness can impact the deformation of UIs when worn and touched, and thus impact the users' perception of the curvature. To investigate how softness impacts users’ perception of curvature, we measured participants’ curvature perception accuracy and precision in different softness conditions. We found that participants perceived the curviest surfaces with similar precision in all different softness conditions. Participants lost half the precision of the rigid material when touching the flattest surfaces with the softest material. Participants perceived all curvatures with similar accuracy in all softness conditions. The results of our experiment lay the foundation for soft curvature perception and provide guidelines for the future design of curvature- and softness-changing UIs.
Many of our activities rely on tactile feedback perceived through mechanoreceptors in our skin. While visual and auditory devices provide immersive experiences, cutaneous feedback devices are typically limited in the range of sensations they provide and are hence usually used and tested on relatively simple synthetic surfaces. We present a device designed in a human-centered process, triggering the mechanoreceptors sensitive to pressure, low-frequency vibrations, and high-frequency vibrations, enabling one to experience touch of complex real-world surfaces. The device is based on a parallel manipulator and a pin-array, that operate simultaneously at 200Hz and emulate coarse and fine geometrical features, respectively. The decomposition into coarse and fine features, alongside the high operation frequency, enable simulation of virtual surfaces. This was corroborated via experiments on complex real-world surfaces via both a quantitative recognition test and a usability questionnaire. We believe that this design can be incorporated in numerous applications.
Fingertip force control plays an important role in learning motor skills. Exoskeleton gloves have been developed to assist with fingertip force control, but having the equipment on the fingers interferes with finger motion control and tactile sensation. Thus, we present a system for assisting with voluntary fingertip force control that does not require any devices to be worn on the fingers. In this study, we focused particularly on lateral pinch force, which is grip force achieved with the pad of the thumb and the lateral surface of the index finger to grasp objects. We use active bio-acoustic sensing to estimate voluntary pinch force with piezo elements attached to the back of the hand and electrical muscle stimulation (EMS) to the forearm to control involuntary pinch force in a closed-loop system. We developed three prototypes and conducted user studies to investigate whether our system can assist with pinch force control under several target forces, from weak to strong. Our user studies showed that the combination of active bio-acoustic sensing and EMS can assist users in maintaining the pinch force closer to the target force.