San Diego Teen Wins $25,000 for a Stethoscope That Costs a Dollar

A $1 circuit board just won a San Diego high school student a $25,000 grand prize. Kayley Xu, a Year 12 student, took the top award in the Mott Million Dollar Challenge for Aucura, a wearable stethoscope built to improve respiratory diagnostics.

Aucura captures and analyses sounds from the body. Its purpose is to help doctors identify breathing-related problems faster and more cheaply than existing tools allow. Xu wants the device to reach rural communities and underfunded clinics, where medical equipment budgets are thin.

"I'm really grateful for experiences like these, as they're really formative in helping young people like me decide what they want to do in the future," Xu told the Mott Foundation after her win.

Why build a new stethoscope?

The idea came to Xu a few months after she recovered from pneumonia. That illness pointed her at auscultation — the process of listening to sounds inside the body. She saw a technology that had barely moved in two centuries.

"It's often done using a stethoscope. This process has existed for over 200 years, but the device itself, the traditional stethoscope, has remained relatively unchanged over that time, which is another part of why I was really motivated to advance this technology," she explained.

Her first move was software alone. That approach failed fast. The available hardware could not produce data clean enough to interpret. So she reversed the order of work and built a sturdier chest piece first — the part of the stethoscope that rests against the body. Only then did she write the software that turns captured sounds into information a doctor can use.

She did not design in a vacuum. Xu consulted doctors throughout the process. "I talked to my paediatric physician about the idea. She was able to look at some of the chest pieces I designed and gave me feedback on them. That validated my idea early on," Xu recalled.

How did she test it?

Testing a medical device on live patients posed an obvious problem for a California teenager. "I wanted to test Aucura in real life, and it's kind of hard to do in vitro tests or tests in live human patients," she said.

Her solution came from her kitchen. She mixed gelatine powder and water, whipped the mixture with an electric baking mixer, and moulded the foam into a model of a human torso. The hard part was the ratio. Sound had to travel through the foam at roughly the same speed it travels through a real chest.

It took many attempts. Xu counts the failures as core to what she learned. When judges at the Mott Million Dollar Challenge asked her to name a trait of entrepreneurship she had demonstrated, she answered by describing those failures.

What makes the economics work?

Digital stethoscopes on the market often cost hundreds of dollars. That price gap is the heart of Xu's design. The flexible circuit board in Aucura can be manufactured in bulk for about one dollar.

That difference matters most where clinics have little money to spend. Xu's target market is the places digital diagnostics usually skips.

"This would allow it to reach areas where medical clinics might not be funded, since it's relatively cheaper and would enable wider access to digital stethoscope technologies," Xu said.

What comes next?

Xu plans to study a STEM subject at university. "I'm really passionate about electrical engineering and biomedical engineering right now," she said. She also intends to keep developing Aucura toward the market.

"I really hope that Aucura can be used in rural areas or less-funded areas, where they might not have access to that many resources. The end goal of Aucura is for it to be ubiquitous, like a new standard in auscultation technology," Xu said.

A dollar of hardware against a 200-year-old device: that comparison, not the prize money, is what could reshape respiratory care in low-budget clinics.