Virtual Reality

The Engineer – WeTac Skin Creates Vivid Touch Experience for Virtual Reality (1)

Researchers in Hong Kong have developed an advanced wireless haptic interface system called WeTac, which is said to provide a “personalized and vivid touch experience” for virtual reality users.

The system, developed by a team at the City University of Hong Kong (CityU), is hand-worn and features soft, ultra-thin features. It collects personalized touch sensation data and has potential applications in games, sports and professional training, social activities and remote robotic controls, the researchers said.

“Tactile feedback has great potential, along with visual and auditory feedback, in virtual reality (VR), so we kept trying to make the haptic interface thinner, smoother, more compact and wireless, so that it can be used freely on the hand, like a second skin,” said Dr. Yu Xinge, associate professor in CityU’s Department of Biomedical Engineering (BME), who led the research.

Together with Professor Li Wenjung, Full Professor in the Department of Mechanical Engineering (MNE), Dr. Wang Lidai, Associate Professor in the Department of Biomedical Engineering (BME) and other collaborators, Dr. Yu’s team developed the system which is described in the scientific journal Intelligence of natural machines.

Existing haptic gloves mostly rely on bulky pumps and air ducts, powered and controlled by cords and cables, which hinder the immersive experience of VR and AR users, the team said. WeTac aims to overcome this with its in-skin wireless electro-touch system.

The system consists of two parts: a minituarized soft control unit, attached to the forearm as a control panel, and a manual hydrogel-based electrode patch as a haptic interface.

The entire speaker weighs only 19.2g and is small enough (5cm x 5cm x 2.1mm) to mount on the arm. It uses Bluetooth Low Energy (BLE) wireless communication and a small rechargeable lithium-ion battery. The hand patch is only 220 µm at 1 mm thick, with electrodes on the palm.

According to the team, he shows great flexibility and guarantees effective feedback in various poses and gestures.

“Electro-tactile stimulation is a good method to provide effective virtual touch to users,” Dr. Yu explained. “However, because individuals have different sensitivities, the same feedback force may be felt differently in the hands of different users. . So we need to customize the feedback settings accordingly to provide a universal tool for all users to eliminate another major bottleneck in current haptic technology. »

WeTac’s ultra-smooth features make it easy to map threshold currents for individual users to determine optimized settings for each part of the hand.

The skin-integrated wireless electro-touch system consists of two parts: a soft control unit (right), attached to the forearm, and the hand patch (left) – Credit: Dr Yu Xinge Research Group / City University of Hong Kong

Based on customized threshold data, electrotactile feedback can be delivered to any part of the hand on demand within an appropriate intensity range to avoid causing pain or being too weak to be felt , confirmed the team. In this way, virtual tactile information, including spatial and temporal sequences, can be reproduced across the entire hand.

WeTac patches are worn on the hands to provide programmable spatio-temporal feedback patterns, with 32 pixels of electro-tactile stimulation on the palm instead of just the fingertips. The average center-to-center distance between the electrodes is approximately 13mm, providing ample coverage on the hand.

Safety measures have been incorporated to protect users from electric shock, and the temperature of the device is maintained within a range of 27°C to 35.5°C to avoid causing thermal discomfort during continuous operation.

In an AR scenario, a virtual mouse hops forward and briefly rests on each hand point. Manual patch, with hydrogel-based electrodes, features 32 palm-side electro-tactile stimulation pixels, allowing threshold currents to be easily mapped for different users – Credit: Dr Yu Xinge Research Group / City University of Hong Kong

WeTac has been successfully integrated into VR and AR scenarios, and synchronized with robotic hands via BLE communication. Users can feel virtual objects in different scenarios, such as gripping a tennis ball during sports training, touching a cactus, or feeling a mouse running over their hand.

Dr Yu describes it as a “powerful tool” for providing virtual touch, adding that the team believes it is inspiring for the development of the metaverse, human-computer interface and other areas.

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