This Really Knits the Spot

Considering the remarkable progress that has been made in areas like display resolution, mobile processing, speaker technology, and body tracking, we might feel like a victory lap is in order. After all, these components come together to create some very impressive virtual reality (VR) experiences with fairly inexpensive, consumer-grade headsets. But while these experiences were unthinkable even a few years ago, they still fall far short of being fully immersive. Sure, we have knocked the audio and visual aspects of VR out of the park, but those are the easy parts. What about the other senses, like smell and touch?

Simulating touch, in particular, is of great interest to VR developers since it makes up such a large component of our sensory experience of the world. There is no quicker way to break the illusion of a virtual world than to reach out to touch a virtual object and feel absolutely nothing. But simulating the feel of an arbitrary object is by no means straightforward. In order to avoid using bulky and heavy devices for this purpose — which in and of themselves would break the illusion — developers have had to compromise. As a result, most systems that simulate touch rely on vibration, which does not provide a high-resolution experience.

Applying pressure to the skin has the potential to offer more realistic experiences than vibration, yet building these types of systems requires something like an exoskeleton to be worn by the user. Without something to press against, the actuators in these devices cannot apply much pressure to the skin. That may change in the near future, however, thanks to a team of engineers at Stanford University. They have developed a soft and flexible sleeve called Haptiknit that can provide realistic pressure-based haptic feedback without any bulky gear.

The device uses a battery-powered pneumatic system with small, inflatable pressure actuators to provide haptic feedback. These actuators are capable of delivering precise sensations of touch, like pressure and strokes. The challenge of anchoring the actuators against the skin without a bulky exoskeleton was solved by incorporating knit fabric into the design. This fabric, made from a blend of nylon, cotton, and thermoplastic fibers, provides a unique balance of stiffness and flexibility. The thermoplastic fibers are heat-treated to create rigid backing for the actuators, right where it is needed, while allowing the rest of the sleeve to remain soft and comfortable for the user.

User testing revealed that Haptiknit delivers more precise and pleasant tactile sensations than vibration-based devices, including the ability to convey emotions and directional cues effectively. Furthermore, participants found the sleeve comfortable, particularly those who had prior experience with haptic devices.

Looking ahead, the team envisions expanding Haptiknit's applications to include navigation, communication, and even rehabilitation. They aim to refine the knitting patterns, develop larger-scale devices, and explore its potential in virtual reality, assistive technologies, and training. By combining functionality with comfort, Haptiknit offers a glimpse into a future where wearable haptic devices might become a normal part of everyday life.