A $3 patch shows promise as the future of smart medical diagnosis

For instance, an Apple Smartwatch (Series 4) has only two electrode sensors that measure the heart’s electrical activity, but a medical-grade 12-lead EKG has 10 electrodes.

"This 12-lead EKG shows what's happening electrically in the heart from 12 different perspectives, or 12 different directions, whereas the Apple Watch gives you that same electrical activity, but really in just one direction,"  Dr. Gregory Marcus, professor at the University of California, San Francisco, told CNET.

However, such medical-grade devices are bulky and require large battery packs. The proposed smart patch, which is only about the size of two stamps, can replace bulky devices and make medical diagnosis easy, accessible, and affordable.   

“It may one-day aid clinicians in assessing muscle injuries and support patients’ recovery,” a press release noted.

How does the smart patch work?

The textile is composed of silver-coated yarn stitched on a nanomagnet-filled rubber patch. It is so sensitive to body movements that even a tiny fluctuation in the amount of mechanical force it experience can change the alignment of the magnetic field inside it. 

The working mechanism of the patch is based on two concepts; the magnetoelastic effect (when magnetic stress changes a material's magnetic properties) and electromagnetic induction (when a change in the magnetic field gives rise to electric current). 

Let’s assume there is a man who underwent a minor accident during cycling and injured his leg muscles. The mechanical force resulting from the injury will deform the magnetic field inside the patch on his leg.

This change will produce electrical signals containing information about the body's damage. All this information will be quickly available on a mobile app to the doctor who is going to treat the injured person. 

“The device converts muscle activities into quantifiable, high-fidelity electrical signals that are sent wirelessly to phone apps. This demonstrates the potential for personalized physical therapies and improving the rehabilitation of muscle injuries,” said senior author Jun Chen in a press statement, assistant professor of bioengineering at UCLA.

Using the patch, the doctors can know to what degree the injured person can safely bend his legs or how much force his legs can withstand during the recovery phase. 

Using the patch in real-world conditions

The researchers tested the patch on various body parts. They measured pulse readings, muscle movement, cardiovascular activity, and other health parameters while the subjects performed everyday activities like walking, exercising, and drinking water.

The device was so accurate and sensitive that the researchers could even identify the affected muscle group (a collection of closely located muscles in a particular body part) during the different body movements. 

It worked well for 100,000 cycles in different conditions involving heavy rain, body sweat, high mechanical stress, and even when stretched 3.5 times its original length. 

Also, apart from being stretchable, durable, and waterproof, the patch is also likely to be super affordable. The researcher claims that a single patch made from their smart textile should cost less than $3. 

“Another highlight of the device is its self-powering properties. The ability to convert biomechanical force to electricity means the device is also a generator. This eliminates the need for bulky, heavy, and rigid battery packs usually needed in wearable electronic designs,”  said Chen.

All these properties make the patch an ideal replacement for electrocardiograms and other heavy medical-grade diagnostic tools. However, this innovative device still needs further optimization, and researchers are currently working towards making it lighter, better, and more suitable for human use. The study is published in the journal Matter on June 27.