Virtual reality (VR) has been on the precipice of transforming how we interact with our worlds through technology for years. So far, however, the haptic systems used in VR have failed to deliver a seamless user-friendly interface that can live up to that promise. That could change with a new advanced wireless haptic interface system, called WeTac, developed by researchers at the City University of Hong Kong (CityU). The system could provide the type of wireless interface that could act as a “second skin” that could help VR reach its potential, said Yu Xinge, associate professor in the department of biomedical engineering (BME) at CityU, who led the research. said.
“Touch feedback has great potential, along with visual and audio information, in virtual reality (VR), so we kept trying to make the haptic interface thinner, softer, more compact and wireless, so it can be used freely on the hand , like a second skin,” he said in a post on CityU’s website.
Worn on the hand and forearm, WeTac collects personal tactile sensation data that can be used to provide a robust touch experience in the metaverse, researchers said. It’s soft and ultra-thin and can seamlessly integrate with VR applications for gaming, sports, skill training, social activities and even remote robot controls, they said.
How the haptic system works
Haptic gloves currently provide the tactile sensation in VR applications, but they typically rely on bulky pumps and air channels powered and controlled by cords and cables. This severely limits the immersive experience of both VR and augmented reality (AR) users, researchers said.
WeTac’s electrotactile system—consisting of two parts—is lightweight, weighing only 19.2 grams, and small enough at 5 cm x 5 cm x 2.1 mm to be mounted on a user’s arm, researchers said . A miniaturized soft driver unit, attached to a forearm, serves as a control panel, while a hydrogel-based electrode hand patch that is 220 µm to 1 mm thick serves as a haptic interface.
The WeTac patches provide programmable spatiotemporal feedback patterns, with 32 electrotactile stimulation pixels on the palm instead of just on the fingertips, researchers said. The average center-to-center distance between the electrodes is about 13 millimeters, providing wide coverage for the entire hand, they said.
WeTac requires no external power source, but instead runs on a small rechargeable lithium-ion battery, and uses Bluetooth low energy (BLE) for wireless communication. Overall, the system offers great flexibility and can provide effective feedback when the user adopts various postures and gestures, researchers said.
Solve individual-user challenges
Since no two VR users are the same, researchers had to solve several issues in designing the system to ensure that its approach to using electrotactile stimulation would provide effective virtual touch for all types of people who wear it, Yu said. . “Since individuals have different sensitivities, the same feedback strength may be felt differently in different users’ hands,” he explained in the post.
To solve this problem, researchers adjusted the feedback parameters accordingly “to provide a universal tool for all users to eliminate another major bottleneck in current haptic technology,” Yu said.
WeTac is also ultra-soft, allowing threshold currents to be successfully mapped for individual users, determining the optimized parameters for each part of the hand, researchers said. Then, based on the personal threshold data obtained by the haptic system, it can provide on-demand electrotactile feedback to any part of the hand in a proper intensity range, they said.
This setup could also avoid the unfortunate scenario of causing a user pain or, on the other end of the spectrum, being so weak that the user doesn’t feel it at all, researchers added. The system also has several built-in safety measures to protect users from electric shock, and maintains a temperature in the relatively low range of 27 degrees to 35.5 degrees Celsius to avoid overheating during continuous operation, researchers said.
Future of virtual reality?
The team published a paper on WeTac in the journal Nature Machine Intelligence. Researchers have already successfully integrated the system into VR and AR scenarios, synchronizing it with robotic hands through BLE communication, researchers said.
So far, these initial applications have yielded positive results, with users reporting that tactile feedback in the hand is much easier and more user-friendly than with other VR haptic systems, they said. Users can actually feel virtual objects in various scenarios—including grabbing a tennis ball in sports practice, touching a cactus or feeling a mouse running on the hand in social activities, researchers reported.
Researchers suggest that WeTac could provide a haptic foundation for the future of virtual touch solutions in not only VR and AR, but also “for the development of the metaverse, human-machine interface (HMI) and other fields,” Yu said.
