The development of an adhesive sensing device has allowed for the seamless attachment of the device to human skin in order to detect and monitor the wearer’s health. The device was created by a team of researchers led by Penn State, who sought to create a smarter skin that could monitor and share specific health information, such as the concentration of glucose in sweat or heart rate. This new technology will enable the detection of health-related signals and provide valuable health information for the wearer.
An article in Advanced Materials revealed the smart skin’s capabilities, such as its ability to be reprogrammed to detect different signals and be recycled efficiently. The paper was part of the “Rising Stars” series, which showcases the work of early career researchers from around the world. Additionally, the researchers applied for a provisional patent for their work.
While there have been extensive efforts to develop wearable sensors for health monitoring, there has been a lack of multifunctional skin-interfaced electronics with natural adhesion on a single material platform that is cost-effective and efficient.
“Our research presents a skin-attachable, reprogrammable, multifunctional adhesive device patch created using inexpensive laser scribing, making it an advancement over current fabrication methods,” stated Huanyu “Larry” Cheng, the co-corresponding author and the James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics in the Penn State College of Engineering. Cheng highlighted the complexity and high cost of traditional flexible electronics fabrication techniques, particularly when sensors are built on flexible substrates that are not inherently flexible. This rigidity of the sensors can restrict their flexibility.The ability of the entire device. Cheng’s team previously developed biomarker sensors using laser-induced graphene (LIG), which involves using a laser to pattern 3D networks on a porous, flexible substrate. The interactions between the laser and the materials contained in the substrate produce conductive graphene.
“However, the LIG-based sensors and devices on flexible substrates are not intrinsically stretchable and can’t conform to interface with human skin for bio-sensing,” Cheng said, noting that human skin is changeable in shape, temperature and moisture levels, especially during physical exertion when monitoring heart rate, nerve performance or sweat glucose levels may need to be measured. “While LIG can be transferred to stretchable elastomers, this process can significantly decrease its quality.”
Cheng explained that as a result, programming a sensor device to monitor specific biological or electrophysical signals becomes more challenging. And even when the device is properly programmed, its sensing performance often suffers.
“To tackle these issues, it is highly desirable to directly prepare porous 3D LIG on the stretchable substrate,” stated co-author Jia Zhu, who earned a doctorate in engineering science and mechanics from Penn State in 2020 and is now an assAssociate professor at the University of Electronic Science and Technology of China.
To achieve their goal, the researchers created a sticky composite using polyimide powders to add strength and heat resistance, and amine-based ethoxylated polyethylenimine dispersed in a silicone elastomer. This stretchable composite allows for direct 3D LIG preparation and can conform to non-uniform shapes, making it suitable for use on human subjects.
The researchers confirmed the effectiveness of the composite through experimentation.The device has the ability to track pH value, glucose, and lactate levels in sweat. It can also detect these levels through finger prick blood draws. In addition, it is possible to reprogram the device to monitor heart rate, nerve performance, and sweat glucose levels in real time. Reprogramming is a straightforward process that involves applying and removing clear tape over the LIG networks. The substrate can then be relasered to new specifications, up to four times before it becomes too thin. Once it becomes too thin, the entire device can be recycled.
Importantly, Cheng states that the device remains sticky and capable of monitoring even when the skin is slippery.The current technology is powered by batteries or near-field communication nodules, similar to a wireless charger. The device has the potential to harvest energy and communicate over radio frequencies. Researchers believe that this will result in a standalone, stretchable adhesive platform that can sense desired biomarkers and monitor electrophysical signals. The team plans to work with physicians to eventually apply this platform to manage diseases such as diabetes and monitor acute issues like infections or wounds. They aim to create the next generation of smart skin with integrated technology.Cheng stated that they are working on developing sensors for monitoring health and drug delivery modules to provide timely treatment.
