Researchers have developed a wearable patch that can detect environmental hazards, such as dangerous gases or heavy metals in water, and notify wearers by vibrating against their skin, according to a July 24 announcement. The team has also adapted the technology for use as an "e-skin" on robotic devices, enabling robots to sense and avoid environmental threats.
The patch is a square device slightly smaller than a driver's license. It contains a microcontroller acting as its brain, a small battery, sensors capable of monitoring six types of environmental hazards, and an actuator serving as the haptic motor for vibrations. Thin-film photovoltaic cells on the exterior allow the device to harvest solar power while worn.
Oluwatobi Ojuade, co-author of the paper and Ph.D. student at NC State, said, "Just having a buzzing motor isn't enough; you need to actually feel it. So, we designed tiny textured surfaces that sit at the interface between the motor and your skin, almost like a miniature pattern of bumps. By changing the size and spacing of those bumps, we could control how the vibration is perceived against your skin. That let us fine-tune the sensation so it actually grabs your attention, instead of feeling like a faint buzz you might miss." The device triggers different vibration patterns depending on which hazard is detected.
In proof-of-concept testing, Uzunoğlu said, "We found that the device did a good job of detecting the hazardous substances and immediately triggering the haptic response. We also found the energy harvesting technology did a good job of extending the life of the battery. Coupled with the low power demand of the sensors, this allows the device to function for around 24 hours." For robotic applications, layering piezoelectric material beneath the sensor patch allows detected vibrations to generate electrical signals readable by robots.
Amay Bandodkar, co-corresponding author and assistant professor at NC State, said, "The patch and e-skin are largely made using off-the-shelf components... That should make it easier to scale up... And...the sensor array is modular...you can add or remove sensors that monitor for whichever hazards are most relevant." Lilian Hsiao added, "To combine something that people would wear along with sophisticated sensing capabilities and alerting ability is something we've been working on for a long time." The research was supported by funding from grants including one from National Eye Institute.
