SkinKit offers versatile, wearable computing on the skin
Personal computing has become smaller and more intimate over the years – from desktop computers to laptops, smartphones and tablets, smartwatches and smart glasses.
But the next generation of wearable computing technology – for health and well-being, social interaction and a myriad of other applications – will be even closer to the user than a watch or glasses: it will be affixed to the skin.
Interfaces on the skin – sometimes called “smart tattoos” – have the potential to surpass the sensing capabilities of current wearable technologies, but combining comfort and durability has proven difficult. Now members of Cornell’s Hybrid body lab have developed a reliable and waterproof interface that is easy to attach and detach, and can be used for a variety of purposes, from health monitoring to fashion.
Doctoral student and lab member Pin-Sung Ku is the lead author of “SkinKit: construction kit for prototyping interfaces on the skinwhich was presented in September at UbiComp ’22, the Association for Computing Machinery’s joint international conference on pervasive and pervasive computing.
“We’ve been working on it for years, and I think we’ve finally solved a lot of technical challenges,” said Cindy (Hsin-Liu) Kao, assistant professor of human-centered design at the College of Human Ecology and lead author of the study. “We wanted to create a modular approach to smart tattoos, to make them as easy as building Legos.”
Other contributors, all former members of the lab, are former postdoctoral researcher Md. Tahmidul Islam Molla, now Assistant Professor of Computer Science Practice at Marquette University; Kunpeng Huang ’21, M.Eng. ’22; Priya Kattappurath ’20, M.Eng. ’21; and Krithik Ranjan ’22.
SkinKit – a plug-and-play system that aims to “lower the entry floor” to interfaces on the skin, Kao said, for those with little or no technical expertise – is the product of countless hours of development , testing and redevelopment, she said.
Kao’s lab is also very aware of cultural differences in general, and she thinks it’s important to bring these devices to diverse populations.
“People from different cultures, backgrounds and ethnicities can have very different perceptions of these devices,” she said. “We thought it was actually really important to let more people say what they want these smart tattoos to do.”
Manufacturing is done with temporary tattoo paper, silicone textile stabilizer, and water, creating a multi-layered thin film structure the group calls “skin tissue.” The layered material can be cut into desired shapes – for their study, the researchers used three-quarter-inch squares, with male-female cut lines so that the pieces can be tessellated (joined together) – and fitted with miniaturized flexible printed circuit modules to perform a range of tasks.
“The starting point was finding a suitable form factor and then making it scalable,” Ku said. “And the way we scale it is through the tessellation pattern. So the user can design a circuit and then customize the layout by putting multiple modules together.”
One of the benefits of their design, Ku said, is component reuse.
“The wearer can easily tie them together and also untie them,” he said. “Let’s say today you want to use one of the sensors for a certain purpose, but tomorrow you want it for something different. You can easily detach them and reuse some of the modules to create a new device in minutes.
Test SkinKit, the researchers first recruited nine participants with both STEM and design backgrounds to build and wear the devices. Their contribution to the 90-minute workshop helped inform further modifications, which the group made before conducting a larger two-day study involving 25 participants from both STEM and design backgrounds.
Devices designed by the 25 study participants addressed: health and wellness, including temperature sensors to detect fever due to COVID-19; personal safety, including a device that would help the wearer maintain social distancing during the pandemic; notification, including an arm-worn device that a rider could wear that vibrates when a vehicle is nearby; and assistive technology, such as a sensor worn on the wrist for the blind that vibrates when the wearer is about to strike an object.
Other applications were for social, fashion and sports training purposes.
Kao said members of his lab, including Ku, participated in the 4-H Career Exploration Conference over the summer, and asked about 10 middle school students from upstate New York to build their own SkinKit devices.
“I think it just shows us a lot of potential for STEM learning, and in particular to be able to engage people who originally might not have an interest in STEM,” said Kao. “But combining it with body art and fashion, I think there’s a lot of potential to engage the next generation and wider populations to explore the future of smart tattoos..”
This work was supported by the National Science Foundation.