For a vascular surgeon like John Martin, the chief medical officer of Butterfly Network, ultrasound imaging--crucial for everything from diagnosing cancer to identifying a baby's gender--has forever been what he sends a patient to get, and then waits to analyze the results of. There's been no other way to do it: Ultrasound technology has always been expensive and bulky, and requires serious expertise to run and interpret.

Butterfly Network smashed that paradigm when it introduced the Butterfly iQ portable ultrasound device, which will make ultrasound imaging widely available and roughly as difficult as operating a smartphone. And at a vastly reduced price: An iQ costs $2,000, versus the $25,000 to $100,000 required for yesterday's ultrasound machinery. Butterfly's sales this year will exceed the 30,000 units sold by the entire industry last year.

The iQ resembles an electric razor; in fact, you'll eventually be able to buy one for home use. "Ultrasound can play a role in every disease stage: discovering, monitoring, or predicting the safest treatment option," Martin says. "It's almost endless." He used one to diagnose his own cancer.

Butterfly Network's CEO, Jonathan Rothberg, a serial biotech entrepreneur, founded the company in 2011 to invent better imaging technology to treat his daughter, who suffers from a rare congenital condition. He funded it with $20 million of his own money, and also took investment from Fidelity and the Gates Foundation. (At least two-thirds of the world's population has no access to medical imaging tech­nology, which makes Butterfly interesting to NGOs.) An A.I. program developed for the iQ uses machine learning to analyze images, while another learns how customers use the machine and teaches them to operate it better. "You can run the whole thing," says Martin, "with your thumb." 

Correction: An earlier version of this article misstated the scale of access to medical imaging technology around the world. At least two thirds of the entire population globally is unable to access the equipment.