An 18-g haptic feedback ring with a three-axis force-sensing skin

Wearable human–machine interfaces could provide immersive, multisensory interactions, turning everyday items into smart haptic devices for virtual and augmented reality. However, the development of tactile wearables with kinaesthetic feedback remains limited by the size and weight of the devices, which restricts portability and comfort. Here we report a haptic ring that weighs 18 g and offers three-degrees-of-freedom force sensing and feedback. The system has an origami-inspired structural base that provides efficient and compact force transmission, and a soft force-sensing skin capable of simultaneously detecting shear and normal forces. The force-sensing skin is made by combining a topology-optimized, laser-patterned layer that has pyramid microstructures with a layer with four resistive pixels, an approach that ensures linear sensitivity and a rapid response time. The ring, which is powered by soft pneumatic actuators and integrated with inkjet-printed bending sensors, can provide kinaesthetic force feedback of up to 6.5 N.