Virtual reality (VR) has been poised to revolutionize the way we interact with our lives through technology for years. However, the haptic systems used in VR have so far failed to provide a seamless user-friendly interface that can fulfill 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 can provide the kind of wireless interface that could act as a “second skin” that could help VR reach its potential, said Yu Xinge, an associate professor in the biomedical engineering (BME) department at CityU, who led the research.
“Tactile feedback, along with visual and auditory information, has great potential in virtual reality (VR), so we continued to try to make the haptic interface thinner, softer, more compact, and wireless, so that it could be used freely on the hand. , like another skin,” he said in a post on the CityU site.
WeTac is worn on the hand and forearm and collects personal tactile sensor data that can be used to provide a robust touch experience in the metric, researchers said. It is soft and ultrathin and can seamlessly integrate with VR applications in gaming, sports, skill training, social activities, and even robotic remote controls, they said.
How the Haptic System Works
Haptic gloves currently provide the sense of touch in VR applications, but they typically rely primarily on bulky pumps and air ducts that are driven and controlled via cords and cables. This severely limits the immersive experience of VR and augmented reality (AR) users, the researchers said.
The WeTac electrolytic system – which consists of two parts – is lightweight, weighing only 19.2 grams, and small enough at 5 cm x 5 cm x 2.1 mm to fit on a user’s hand, the researchers said. A miniaturized soft driver unit, attached to a forearm, serves as a control panel, and a 220-µm to 1-mm thick hydrogel-based electrode hand patch serves as a haptic interface.
The WeTac patches provide programmable spatiotemporal feedback patterns, with 32 electro-visually stimulated pixels on the palm instead of just on the tip of the finger, the researchers said. The average center-to-center distance between the electrodes is about 13 millimeters, providing broad coverage for the entire arm, they said.
WeTac requires no external power source, instead running 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 different postures and gestures, the researchers said.
Solving Single User Challenges
Since no two VR users are alike, researchers had to solve several issues in the system’s design to ensure that their approach to using electrostatic stimulation would provide effective virtual contact for all types of wearers, Yu said. “Since individuals have different sensitivities, the same feedback strength could be felt differently in the hands of different users,” he explained in the post.
To solve this issue, the researchers customized the feedback parameters 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, the researchers said. Then, based on the personalized threshold data the haptic system receives, it can provide electrostatic feedback to any part of the hand on demand in the right intensity range, they said.
This arrangement can also avoid the unfortunate situation of user pain or, on the other end of the spectrum, being so weak that the user doesn’t feel it at all, researchers added. Moreover, the system has built in several safety measures to protect users from electric shock, and maintains a relatively low temperature range of 27 degrees to 35.5 degrees Celsius to avoid overheating during continuous operation, the researchers said.
The Future of Virtual Reality?
The team published a paper on WeTac in the journal Nature’s Machine Intelligence. Researchers have already successfully integrated the system into VR and AR scenarios, synchronizing it with robotic arms via BLE communication, the researchers said.
So far these initial applications have provided positive results, with users reporting that tactile feedback in the hand is much easier and easier to use than with other haptic VR systems, they said. Users can feel virtual objects in a variety of situations — including holding a tennis ball in sports training, touching a cactus, or feeling a mouse running on the hand in social activities, the researchers reported.
Researchers imagine that WeTac can provide a haptic foundation for the future of virtual-touch solutions not only in VR and AR but also “for the development of the metaverse, human-machine interface (HMI), and other fields,” Yu said.
