Printing Sensors on the Skin – Is the Borg Collective Here?
Spend the day at California’s Rock West Solutions and you will discover all sorts of sensors with a wide range of commercial applications. Sensor development and signal processing is what Rock West specializes in. Being an industry leader, they are not surprised by new research into printed wearables, research that may remind the most ardent Star Trek fans of the Borg collective.
The wearables in question are sensors printed directly on human skin. They are flexible sensors, capable of monitoring a variety of biometric signals. For all intents and purposes, they represent the marriage between man and machine. Thus the reference to the Borg collective. In the fantasy world of Star Trek, the Borg are a race that figured out how to seamlessly integrate living tissue with machines.
Protecting Sensitive Skin Tissue
Previous engineering efforts made it possible to print flexible circuit boards for use in wearable devices. The metal components of the circuit boards require a lot of heat – 572°F to be exact – to bond together. The bonding process is known as sintering.
Engineers are not too worried about sintering when printing circuit boards. The plastic base material is more than capable of handling high heat. Human skin is another matter. Metal particles at 572° would severely damage skin tissue. So the researchers had to come up with a different sintering process.
A Room Temperature Solution
Researchers at Penn State worked with their counterparts in China to come up with a nanoparticle they could add to their mixture of metal materials. This particle allowed the silver in the mixture – the one that causes the most problems – to sinter at a much lower temperature. However, they were only able to get the temperature down to 212°F. That is still too high for skin tissue.
Modifying the mixture solved the problem. They created a new aid layer they could lay down first, followed by the silver layer for printing. The aid layer facilitates sintering at room temperature. For the record, the aid layer is comprised of polyvinyl alcohol paste and calcium carbonate.
A Breakthrough for Wearables
The engineers at Rock West say the research represents nothing less than a breakthrough for wearables. Being able to print wearables directly on skin opens the door to more accurate readings and greater specificity. This could be the very thing wearable designers have been looking for all these years.
Imagine a printable wearable being applied to the skin directly over the heart. It would allow for a much more accurate reading of heart rate as compared to a device worn around the wrist. But there is more. Such a device would make it easier to measure an irregular heartbeat with near flawless accuracy.
Wearable sensors could theoretically measure everything from body temperature to blood oxygen levels on a continuous basis. Add in a bit of wireless technology and the sensors can send data to network systems in real time. This could allow for remote monitoring of the patient’s vital signs, for example.
Durable, Removable, and Safe
The engineers responsible for developing these printed wearables say the devices are durable, removable, and safe. They can be worn for weeks on end as long as they are not exposed to hot water. They can be easily removed in a hot shower without damaging the devices themselves. That means the devices can also be recycled.
Removal doesn’t damage the skin either. As such, there are few worries about recommending them for regular use. Wearable sensors are safe for human beings while simultaneously making it possible to accurately measure a full range of biometric signals.