Recent advances in scientific research may allow robotic prosthetics and virtual reality simulations to be more effective than ever before. Hong Kong researchers have developed new, glove-like technology that not only allows users to experience sensations in their hands when interacting with virtual objects, but also adapts the intensity of the sensations according to the individual’s nerve sensitivity level.
Haptic technology is defined as technology that relies on computer-induced forces, vibrations, or motions to provide humans with an artificial sense of touch. Along with virtual reality, this technology has become more relevant in the medical field over the past decade. Not only do surgeons rely on virtual reality to perform surgery, but haptic technology can vastly improve the lives of amputees with robotic prosthetics. In recent years, researchers have discovered that robotic prosthetics significantly reduce the mental effort required to operate the prosthetic, along with the ability to provide patients with a sense of artificial touch. A prosthetic sense of touch may also improve patients’ overall ability to control prosthetics.
While scientists have developed haptic technology for clinical application in the past, previous efforts have often been cumbersome, inconvenient to use, and not customizable for each user.
Now, researchers have developed a new iteration of haptic technology that includes an ultrathin, glove-like technology called WeTac. WeTac incorporates multiple electrodes into the glove structure and provides users with electrical feedback to generate tactile sensations across their hands. Not only does this technology have the potential to improve the outcome of robotic surgery, but it is an important development in haptic technology that can be applied to people with disabilities and those who use robotic prosthetics.
The first challenge in creating WeTac was to come up with a design that could simulate the dynamic and changing sensations that people feel when using their hands.
Consider the experience of shaking a person’s hand. You may feel the handshake only in parts of your palm or fingers. These areas of contact may change as you go through their handshake movements. Your grip pressure or their grip may also change. Furthermore, some areas of our hands are innately more sensitive to touch than others. The feelings we experience in our hands are very dynamic, even for something as basic as shaking someone else’s hand.
The goal of Yao et al. The aim was to design a haptic glove that could capture these dynamic sensations as users interacted with virtual objects. To do so, the WeTac was designed with 32 electrodes spread across the palm surface and fingers. This will allow researchers to adjust the intensity of electrical signals at 32 different points on the hand and generate more precise sensations of touch across the hand.
The use of electrodes to create artificial sensations also enabled Yao et al. To create WeTac incredibly lightweight. Electrodes have previously been used in thin, wearable devices and can sit directly on the skin without causing any irritation. This makes them optimal for creating light and convenient devices.
Using electrodes, Yao et al. Can induce electrical current throughout the arm. The idea was that these electrical currents would activate nerves in a person’s hand, effectively producing the sensation of touch that a person might feel when interacting with a physical object. Yao et al. WeTac is designed so that electrical currents are produced by a blue control unit that will be attached to the user’s wrist. This control unit will have wireless capabilities and can be controlled from a phone or computer. This will allow WeTac users to move freely.
To test the tool, the first step for Yao et al. WeTac’s electrical stimulation settings were to be adapted according to each participant. The sensitivity level of people’s hands can vary across populations. For example, men generally exhibit less sensitivity to touch than women. Older people also show less sensitivity than younger people. To optimize the tool, Yao et al. Average electrical stimulation thresholds were measured for each participant and for each of the 32 electrodes on their arm.
As expected, on average, women had lower thresholds for electrical stimulation than men. Younger individuals also exhibited lower thresholds. The exception to this pattern was that women who exhibited a large number of calluses on their hands due to their work had a higher threshold. In other words, Yao et al. Beyond gender and age, hand sensitivity can also vary depending on a person’s job or daily activities, it found.
After calibrating the WeTac according to each volunteer’s sensitivity level, Yao et al. WeTac was ready to test it in a virtual reality simulation. In the first simulation, participants slowly held a virtual tennis ball and a virtual cactus. This simulation will allow researchers to determine whether WeTac can produce different sensations according to the texture of a static virtual object. After running the simulations, the team found that the tennis ball could produce a mild tactile sensation, while the cactus produced a spike sensation that was slightly painful or uncomfortable.
The researchers also tested a simulation where a virtual mouse and a piece of cheese appeared in participants’ hands. The participant will then report the sensations they feel as the virtual mouse travels over their hand to eat each piece of cheese. This allowed the researchers to determine that WeTac can effectively induce the sensation of touch for a moving, moving object.
Overall, this study demonstrates significant progress in haptic technology. As WeTac and other lightweight haptic feedback devices continue to be developed, we may begin to see more complex virtual reality technology and robotic prosthetics that utilize haptic feedback and improve remote/robotic surgery as well as the lives of amputees.