MakerBot Stories | Teen Turns Smartphone Into Stethoscope


When high school students learn how to 3D print, they’ll often start with a smartphone case. It seems simple, it’s practical, and it’s personal. Something they’ll have with them — and, while carrying it around, they will think about how to make it better.

Suman Mulumudi didn’t wait for high school. Last summer, between eighth and ninth grades, Mulumudi’s parents bought him a MakerBot Replicator 2 Desktop 3D Printer. Designing his iPhone case took a couple of weeks. Some teenagers customize theirs with a Darth Vader silhouette. Mulumudi added a diaphragm that collects low-frequency sounds and sends them through a tube to the microphone, turning his iPhone into a stethoscope. He named it the Steth IO, made more 3D printed prototypes, and founded a company called StratoScientific, which applied for a patent and plans to seek FDA approval.


“People have tried to put the microphone over the chest, but that doesn’t work,” said Mulumudi, who is 15 and lives in Snohomish, WA. “Interestingly enough, that’s how the first stethoscope was invented.” Before 1816, he explained, doctors used to put their ears to patients’ chests. Then a young woman went to see the French physician René Laennec. He rolled up a piece of paper like a megaphone, and put the narrow end to his ear.

Mulumudi’s father, Mahesh, is a cardiologist, so heart murmurs are dinner conversation, and Suman couldn’t believe doctors couldn’t record the data from the sound of the heart. (Mahesh and Suman are now business partners.) Suman Mulumudi has also prototyped the LesionSizer, which uses the technology behind an optical mouse to help a doctor performing an angioplasty use the right stent.

When Mulumudi was in sixth grade, a few parents pooled money to buy his school a MakerBot Thing-O-Matic. “We put it together. We used it for about half a year. That got me exposed, to the extent that I could see the power 3D printing would have,” he says. So when Mulumudi started on the Steth IO, “the first thing that came to mind for prototyping was 3D printing.”

That was at his old school. He now attends The Lakeside School, in Seattle, where Microsoft founders Paul Allen and Bill Gates went to school. And Mulumudi’s dream is to be an entrepreneur. “People like Bill Gates, Steve Jobs, Jeff Bezos, Howard Schultz — mostly Washington people — they all did one thing: They took an idea and expanded that concept into something that changed the world.”