Wearable sensors to be printed directly on the skin

Driven by Penn State University’s Larry (Huanyu) Cheng, the US and Chinese researchers and scientists have developed an innovative, easier, and more accurate technique that makes biosensors to be printed directly on the skin. Wearable sensors allow for a faster and more accurate monitoring of health parameters such as body temperature, electrical heart signals, blood oxygen saturation, and even hydration levels. 

Wearable sensors are a massive leap from the sweat monitor developed by Cheng and his colleagues. Unlike other wearable technologies, the new biosensor does not require batteries or experience any downtime for recharging. Most importantly, they have worked on allowing the movement from normal day-to-day activities to provide the biosensor with energy to be captured, stored, and used to minimize disrupting daily routines. 

We are interested in applying this multifunctional, wearable sensing technology for diagnostic confirmation and timely treatments for cardiopulmonary diseases, including Covid-19, pneumonia, and fibrotic lung diseases. – said Larry (Huanyu) Cheng, Assistant Professor of Engineering Science and Mechanics, Penn State University 

Keeping ease and accuracy as their key drivers, Cheng and his team have even factored in the possibility of incorporating additional components in the future. Currently, in its prototype stage, the wearable biosensor can accurately measure body temperature, changes in skin moisture, blood oxygen and saturation levels, and even electrophysiological signals such as those noticed on an ECG. The close contact of the biosensor to the skin ensures its accuracy.

While making wearable sensors, the team of scientists has successfully overcome the common concern of metal components being printed onto the skin, having a very high temperature, and causing burns on the skin. A paint paste containing polyvinyl alcohol and calcium carbonate, ingredients commonly found in peelable face masks, is first applied onto the skin. Other nanoparticles like aluminum, magnesium oxides, metallic salts, and copper act as cooling agents to allow the biosensor made of silver nanoparticles to be printed onto the skin at a safe room temperature. The printing process is completed with cold air blown onto the skin to dry out the residual water from the ink to bond the sensor to the skin. 

It could be recycled since removal doesn’t damage the device. And importantly, removal doesn’t damage the skin, either. That’s especially important for people with sensitive skin, like the elderly and babies. The device can be useful without being an extra burden to the person using it or to the environment. – said Larry (Huanyu) Cheng, Assistant Professor of Engineering Science and Mechanics, Penn State University 

While long-term trials are still being carried out to see if the wearable sensors can be worn over several weeks or months, Cheng has confirmed that the sensor is resilient to colder temperatures and can be easily removed with hot water without causing any damage to the skin. Further research is being carried out for a more ‘sophisticated wireless link-up for the biosensor in the future’ to welcome the possibility of printing flexible circuit boards onto paper and fabric using similar technology. 

Connecting the biosensor’s use in aiding those infected with the COVID-19 virus has also been a big factor that stands out here. With its quicker, continuous, and accurate measuring and monitoring of vitals, the biosensor has the potential to alert healthcare professionals of any deteriorating parameters in sick, fragile, and/or hospitalized patients. The wearable sensors are quickly proving its significance, especially for professionals working in dangerous or remote environments.