Nils‐Krister Persson

Electrotactile stimulation can evoke a wide range of sensations, including taps, squeezes, and strokes. Although verbal descriptors are available for vibrotactile and ultrasound stimuli, a comprehensive list has not been developed for electrotactile experiences. To address this, we used a text normalization approach to generate descriptors for wearable electrotactile research and design. In Experiment 1 (N=14), Dutch participants provided 504 open-ended descriptions in response to 36 electrotactile stimuli on the forearm. These were processed into 71 unique English descriptors with considerable inter-rater reliability. Experiment 2 (N=24) evaluated a reduced list of 42 descriptors under additional stimulation conditions, showing robust and consistent descriptor usage, also across varying stimulus intensities. This list partially overlaps with previous non-electrotactile descriptor lists but also includes terms that seem to be unique to electrotactile sensations. Altogether, our findings contribute to the development of common verbal descriptors for electrotactile stimulation, supporting future wearable haptic research and design.

Soft robotics employs deformable materials and structures to achieve compliance and adaptability,enabling safe and close interaction with humans. Merging electromechanically active polymer actuation with textile technology enables soft, large area actuators with form factors being 1D (fibers), 2D (fabrics), or 3D (garments), all relevant for wearable soft robotics. This study investigates in‐air actuating polypyrrole (PPy)‐based trilayer tape yarns (TYs) and the effect of integrating them into woven fabric actuators. Individual TYs are developed, consisting of two polypyrrole layers sandwiching a poly(vinylidene fluoride) (PVDF) membrane filled with anionic liquids (IL). The impact of ionic liquid, PPy thickness, and frequency response on displacement and blocking force is investigated. Individual TYs offer the highest displacement of 30.6 ± 3.6 mm (±1.5 V) at 2.5 mHz and blocking force at 0.20 ± 0.07 mN (±1.0 V, 2.5 mHz). Next, weaving is used to integrate TYs into plain weave actuating fabrics, enabling the assembly of many TYs together without a decrease in displacement. Additive force in woven actuators scales linearly with increased force up to 1.13 ± 0.18 mN (5 TYs), addressed by integrated conductive yarns. Multiarea fabric actuation is demonstrated, as well as an on‐body wearable application of the fabric actuator.

To design complex wearable haptic interfaces using pressure, we have to explore how we can use pressure stimuli to their full potential. Haptic illusions, such as apparent motion and apparent location, can be a part of this. If these illusions can be evoked with pressure, haptic patterns can increase in complexity without increasing the number of actuators or combining different types of actuators. We did two psychophysical experiments with pressure stimuli on the forearm using a pneumatic sleeve with multiple, individually controlled McKibben actuators. In Experiment 1, we found that spatial integration of two simultaneously presented stimuli occurred for distances up to 61 mm. In Experiment 2, we found that apparent motion can be elicited with distinct pressure stimuli over a range of temporal parameters. These results clearly show spatio-temporal integration in the somatosensory system for pressure stimuli. We discuss these findings in relation to effects found for vibration and the mechanoreceptors in the glabrous skin.