Fully 3D-Printed, Stretchable, and Conformable Haptic Interfaces

Integrating rich cutaneous haptic feedback enhances realism and user immersion in virtual and augmented reality settings. One major challenge is providing accurately localized cutaneous stimuli on fingertips without interfering with the user's dexterity. This sub 200 mu m thick, fully printed, stretchable Hydraulically Amplified Taxels (HAXELs) enable both static indentation and vibrating haptic stimuli, localized to a 2.5 mm diameter region. The HAXELs are directly bonded to the user's skin, are soft enough to conform to any body part, and can be fabricated in dense arrays with no crosstalk. All functional materials (elastomers, stretchable conductors, and sacrificial layers) are deposited by inkjet printing, which allows rapid prototyping of multi-material, polymer-based structures. The actuators consist of oil-filled stretchable pouches, whose shape is controlled by electrostatic zipping. The 5 mm wide actuators weigh <250 mg and generate cutaneous stimuli well above reported perception thresholds, from DC to 1 kHz. They operate well even when stretched to over 50%, allowing great freedom in placement. The 2 x 2 arrays are tested on the fingers of human volunteers: the actuated quadrant is correctly identified 86% of the time. Printing soft actuators allows tailoring dense and effective cutaneous haptics to the unique shape of each user.