Embroidered Patches Might Be Making A Comeback - In Medicine

This week’s paper can be found here: Monitoring vital signs over multiplexed radio by near-field coherent sensing

When was the last time you went to a doctor for a checkup? Most appointments start off by reading and recording patient vital signs, such as body temperature, blood pressure, pulse, and blood oxygen saturation, using oral thermometers, automated blood pressure cuffs, and finger-clip pulse oximeters. Often, these systems will be used simultaneously for the sake of time, making the experience momentarily uncomfortable for patients. 

Hospital patients and people with chronic illnesses often feel this uncomfortable all the time, as their vitals must be monitored over days, weeks, months, or years. Most of the current ways that we monitor vital signs require direct skin contact, which can also require hair removal, and limit your range of motion to the length of the cord that you are attached to. Even wireless systems can be uncomfortably restrictive. Worse, not all methods of monitoring vital signals can acquire all of the information a doctor may need, so patients may need to use multiple systems for different health needs. 

Fortunately, researchers at Cornell University are developing a new method to record vital signs without being in direct contact, using a concept called near-field coherent sensing, or NCS. By bouncing electromagnetic energy off of sensors sewn into clothing near the chest or pulse points on the wrist, they can detect movements associated with breathing and pulse and can measure blood pressure. 

They started by analyzing the current methods of monitoring vital signs, looking for common pitfalls of that might be remedied using NCS. This includes small signals that may not be apparent on the surface of the skin, such as pulse and blood pressure, or small motions that may be difficult to record otherwise, such as chest displacement with breathing. NCS uses more electromagnetic energy than other systems, which makes small signals easier to see. It also uses a shorter wavelength of energy, which, when it scatters off a surface, results in larger phase changes than other systems. This phase change can be used to monitor breathing by amplifying the signal associated with chest movement.

With their target vital signs in mind, the Cornell researchers developed an electromagnetic simulation of the human body and placed sensors near the heart and wrist. Upon running the simulation, they saw that the breathing rate and heart rate could be extracted from the signal reflected from the sensors. They were also able to record blood pressure because blood pressure can be derived from heart rate and pulse. In an effort to expand this technology to recording multiple patients at once, they developed small electronic tags that can be sewn into clothing. These tags are called RFID tags, and are very commonly used for everyday tracking - this is how your library knows when you’ve left with a book that you haven’t checked out. 

While the results they show have been modeled in electromagnetic simulation software, it would not be difficult to translate this simulation into a physical device. After all, RFID tags are all too common in everyday technology, and can easily be incorporated into clothing. Incorporating NCS into vital monitoring has the potential to result in more accurate, comfortable, convenient, and low-cost healthcare. In the near future, we may be monitoring our vitals with the same ease that we check out a book from the library.