When it comes to staying healthy, it is often said that early detection is the best protection. This is more than just a nice rhyme worthy of being plastered beneath a stock photo of smiling people in a brochure in your doctor’s office — it contains real wisdom. Many medical conditions are highly treatable in the very early stages, but as time goes by the chance for a positive outcome diminishes greatly.
The problem is that early detection of medical conditions is not entirely easy. Taking time out of one’s busy schedule to undergo a battery of tests when nothing seems amiss is just not many people’s idea of a good time. Because the standard diagnostic process is so cumbersome, many treatable medical conditions are unfortunately not detected until it is too late. But that may no longer be the case in the future. Wearable medical devices offer the promise of continually monitoring our health without being cumbersome.
These devices are not yet entirely practical, however, so they are infrequently used. To really make a positive impact on human health this will need to change. A team led by researchers at Osaka Metropolitan University has recently put forth a new wearable system that they believe is a step toward deploying wearable medical devices far and wide. Their system leverages edge computing to process data on-body, sidestepping a number of issues related to privacy and network connectivity in the process.
The base of the device is a polyethylene terephthalate (PET) film on which silver electrodes are screen-printed on both sides. These electrodes are connected by silver paste applied after laser-cutting the PET film, and an additional PET layer is laminated over the electrodes for protection. For respiration monitoring, a strain sensor made from a porous, laser-induced graphene (LIG) and polydimethylsiloxane (PDMS) composite is bonded onto the PET film. A polyimide (PI) film is first laser-processed to form the LIG, which is then coated with PDMS. After curing, this film is peeled away, transferring the porous LIG structure into the PDMS layer for high sensitivity in strain detection.
The temperature sensor is built on a separate PI film, where a thin Cr/Au metal layer is deposited to enhance the sensitivity. This metal layer is later laminated onto the PET base using adhesive tape and silver paste to ensure stable electrical connectivity. A skin humidity sensor is made by synthesizing zinc indium sulfide nanosheets on interdigitated LIG electrodes on another PI film. Holes are added to the PI film to allow airflow, and the sensor is laminated onto the PET base, providing both environmental access and electrical connection through silver paste.
The sensor patch is connected to a small circuit board with a Bluetooth-capable microcontroller. This makes it possible to wirelessly transmit the sensor data to a nearby smartphone for processing. Custom machine learning algorithms were developed to run on this device, where they can recognize the presence of medical conditions such as heart arrhythmia, coughing, and falls. The prototype device was demonstrated to be capable of detecting these conditions accurately in 80 percent of cases — a respectable achievement, although the performance would need to be increased significantly before it could be used for real-world applications.
By continually monitoring the health of users of this device, and remotely transmitting the findings to their healthcare providers, it is hoped that treatable conditions will be routinely caught early in the future. But before that can happen, the device will need to be made a bit more practical. In particular, the rigid circuit board and relatively large battery will need some work to increase comfort for daily use.This wearable device uses edge computing to track the user’s health (📷: G. Matsumura et al.)
A closer look at the design of the sensor patch (📷: G. Matsumura et al.)
