Wearable electronic health patches now cheaper and easier to make
30 September 2015
Disposable, tattoo-like health monitoring patches can be cheaply and easily manufactured for a wide range of vital signs and medical condition observations.
A team of researchers in the Cockrell School of Engineering at The University of Texas at Austin has devised a method of producing inexpensive and high-performing wearable patches that can continuously monitor the body's vital signs for human health and performance tracking, potentially outperforming traditional monitoring tools such as cardiac event monitors.
Led by Assistant Professor Nanshu Lu, the team's manufacturing method aims to construct disposable tattoo-like health monitoring patches for the mass production of epidermal electronics, a popular technology that Lu helped develop in 2011.
The team's breakthrough is a repeatable 'cut-and-paste' method that cuts manufacturing time from several days to only 20 minutes. The researchers believe their new method is compatible with roll-to-roll manufacturing - an existing method for creating devices in bulk using a roll of flexible plastic and a processing machine.
Reliable, ultra-thin wearable electronic devices that stick to the skin like a temporary tattoo are a relatively new innovation. These devices have the ability to pick up and transmit the human body's vital signals, tracking heart rate, hydration level, muscle movement, temperature and brain activity.
Although it is a promising invention, a lengthy, tedious and costly production process has until now hampered these wearables' potential.
"One of the most attractive aspects of epidermal electronics is their ability to be disposable," Lu said. "If you can make them inexpensively, say for $1, then more people will be able to use them more frequently. This will open the door for a number of mobile medical applications and beyond."
The UT Austin method is the first dry and portable process for producing these electronics, which, unlike the current method, does not require a clean room, wafers and other expensive resources and equipment. Instead, the technique relies on free-form manufacturing, which is similar in scope to 3D printing but different in that material is removed instead of added.
The two-step process starts with inexpensive, pre-fabricated, industrial-quality metal deposited on polymer sheets. First, an electronic mechanical cutter is used to form patterns on the metal-polymer sheets. Second, after removing excessive areas, the electronics are printed onto any polymer adhesives, including temporary tattoo films. The cutter is programmable so the size of the patch and pattern can be easily customised.
After producing the cut-and-pasted patches, the researchers tested them as part of their study. In each test, the researchers' newly fabricated patches picked up body signals that were stronger than those taken by existing medical devices, including an ECG/EKG, a tool used to assess the electrical and muscular function of the heart. The team also found that their patch conforms almost perfectly to the skin, minimising motion-induced false signals or errors.
The team is now trying to add more types of sensors, including blood pressure and oxygen saturation monitors, to the low-cost patch.
A paper describing the manufacturing process is published in the journal, Advanced Materials.