Electrical Engineering undergraduate student Sangwon Cha presented his sweat-rate sensor at the IEEE-EMBS International Conference on Body Sensor Networks in October. (Photo/Rania Soetirto)
From the minimalist Whoop band to the sleek Oura ring, both the medical and commercial sectors have shown interest in tracking real-life biometrics, highlighting the growing focus on improving human health.
In 2020, a survey organized by Deloitte found that 30% of American adults use wearable technology to track some aspect of their own health. These devices offer real-time health insights, which allows users to monitor vital signs such as heart rate, sleep patterns, to stress levels, empowering individuals to be more proactive on their health management through a more personalized 24/7 data-collection process.
For Sangwon Cha, his interests lie in sweat rate, a common indicator of hydration for the human body.
“Sweat is one of the most popular analytes among the wearables community as it is readily available on the human skin and its acquisition is non-invasive,” Cha said. “Monitoring sweat rate reveals key physiological conditions such as hydration levels and heat tolerance. Recent developments in wearable technology have yielded numerous promising solutions.”
Cha is one of the undergraduate students working at the Khan Lab, led by electrical engineering professor Yasser Khan. (Photo/Rania Soetirto)
A typical sweat rate for a healthy, average-sized person hovers around 500 mL per hour, according to Cleveland Clinic. On average, a person may lose up to 2 liters of fluid while exercising. By monitoring an individual’s sweat rate, users could tell when they should keep themselves hydrated or increase their water intake.
In a project led by his graduate student mentor Mohammad Shafiqul Islam, Cha has been working on creating a lower cost and more accurate sweat sensor that could wirelessly connect to smartphones via Bluetooth. Their homegrown app is currently compatible with Android devices.
Cha’s abstract was accepted for presentation at the IEEE-EMBS International Conference on Body Sensor Networks. A leading event in the field of sensors and systems for digital health, the conference took place in Chicago, Illinois from Oct. 15-17. Sponsored by the U.S. National Science Foundation, the conference boasts a diverse audience from academia, business, and healthcare.
The project, which was developed under the Khan Lab at USC, aims to improve a number of issues within sweat rate sensing wearables. The project proposes a lower and more cost effective fabrication solution to create these sensors. The Khan Lab, which focuses on wearable medical electronics for precision health and psychiatry, is currently led by Yasser Khan, an assistant professor of Electrical and Computer Engineering.
“I really thrived under the lab’s collaborative environment,” Cha said. “it was so interesting to see a wide range of projects within the lab, ranging from the device-level all the way to the systems-level.”
Unlike most sensors that track sweat by measuring an electrical property of sweat called admittance, Cha’s sensor measures a different electrical property called capacitance, which provides more accurate and reliable results. This approach allows for easier calibration and reduces the chances of errors, a selling point that he presented at the conference.
In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. However, the relationship between this change in admittance due to sweat and flow rate (sweat rate) is complicated, which makes conversions from admittance to flow rate tricky and unreliable.
“During my time in Korea, caring for people with special needs and directly making an impact to improve their quality of care was very meaningful.” Cha said. “I started to think of ways I could combine my newfound interests in healthcare and engineering.”
According to Cha, most sweat sensors in academic research still measure sweat rate using admittance, to which he is proposing the use of capacitance to tackle this problem.
Originally from South Korea, Cha spent most of his youth living in the U.S. and South Korea before attending USC. He originally enrolled with the intent of graduating with an environmental engineering degree. However, his changing interests influenced him to change his major a number of times.
His return to electrical engineering was sparked by his time at mandatory military service in South Korea. During the pandemic, he completed his service by working in a center caring for individuals with special needs in Seoul. This experience sparked his interest in creating biomedical instruments that could improve people’s quality of life.
“During my time in Korea, caring for people with special needs and directly making an impact to improve their quality of care was very meaningful.” Cha said. “I started to think of ways I could combine my newfound interests in healthcare and engineering.”
“As I learned more about medical devices, I realized that I should switch back to electrical engineering so I could better understand the engineering principles behind these tools,” he added. “It was definitely a full circle moment.”
Cha attributes his success to the mentorship and guidance of Khan and his PhD mentor, Shafiq, whose passion for improving wearable medical devices had shaped his own interests in the field.
“I found myself feeling dedicated to my project shortly after joining the Khan lab. The lab’s welcoming atmosphere allowed me to stay motivated and persistent,” Cha said.
Cha plans to pursue a PhD in electrical engineering and aims to enter into the medical device industry, focusing on commercialization and non-engineering aspects like business and law. He will be graduating from USC in the Spring of 2025.
Published on November 20th, 2024
Last updated on November 20th, 2024
