Wearable biometric sensors to check our vital parameters

Innovation and technology are keeping to make great strides and every day we discover new inventions that could revolutionize our way of life. 

A team of engineers and researchers from Pennsylvania State University has carried out many studies and analyses to manage to create precise biometric sensors that could guarantee high performances and above all could be wearable devices. 

The flexible electronic circuits can be printed directly on human skin, as if they were patches, or rather, real “hi-tech tattoos”, to monitor our state of health such as heart rate, body temperature, blood oxygen levels and external humidity. The creators say that the sensors will also help identifying the different symptoms of the Coronavirus. 

The team led by Huanyu Cheng, Dorothy Quiggle Career Development Professor in the Penn State Department of Engineering Science and Mechanics, however, had to face some challenges regarding the circuits printed directly on human skin, publishing then the results obtained on ACS Applied Materials & Interfaces. 

Printing the flexible device directly on skin has been hindered by the process, called sintering, of bonding the sensor’s silver nanoparticles together which requires temperatures up to 300 degrees, and as stated by Cheng: “the skin surface cannot withstand such a high temperature, obviously”. The team then had to look for a solution by adding an aid layer between the body and the sensors, now the sintering reached a temperature of 100 degrees, but is still too high not to damage our skin. Then, the team “changed the formula of the aid layer, changed the printing material” thus discovering that it can sinter at room temperature. “We do not need to rely on heat to sinter” because the new aid layer was created using polyvinyl alcohol paste and calcium carbonate and a cold air flow, such as that of a hair dryer, is sufficient to eliminate the water used as a solvent in the ink. 

The new sensors are also ecological and the construction process takes place with complete respect to the environment. They are resistant to warm water and can be easily removed with hot water which does not deteriorate them, thus making them recyclable. The innovative “hi-tech tattoos” have been created so as not to damage any type of skin, not even the most sensitive one. 

In short, the university’s team of researchers seems to have found the right solution to constantly monitor our vital parameters in a really simple, innovative and advantageous way.