Signos was created by brothers Neil and Stewart Bartlett, a doctor and engineer respectively in Adelaide, Australia.

"In 2001 when I was practicing as a physician, a colleague with a stethoscope said, 'you can you make this more useful by building an ultrasound into it,'" said Neil Bartlett. "Once I got it into my head I couldn't let it go because there was nothing in the market remotely close to that vision," he said.

He teamed up with his brother Stewart who had spent much of his career in ultrasound and worked in the semiconductor industry in Silicon Valley. They formed Signostics and secured funding from government grants and venture capitalists starting in 2005.

"The hard part was turning that vision to a reality," said Neil Bartlett, now chief executive of the startup. "The breakthrough the engineering team made was figuring out how to create an image with a single crystal," he said.

The first ultrasound machines used a single ultrasound crystal. It was mounted on an articulated arm that dragged the crystal across an area of interest to firm an image.

Today's systems use arrays of 64 to 1,000 crystals to get a crisp image without needing to move the device or the patient. However the systems cost tens of thousands of dollars, in part because the crystals cost several hundred dollars each.

Signostics' engineers decided to use just one crystal paired with a silicon gyroscope instead of a mechanical arm. The gyro keeps track of the crystal's position to form an image as a doctor moves the device over an area of interest.

Signostics designed separate 3.5 and 7.5 MHz transducers into a quarter-sized caps that screw on to the tip of a probe. Thus caps with different frequency crystals for different types of scans can be easily switched. Competing systems use separate probes for different frequencies.

The Signos delivers a 240x320 pixel image on its 41x55 mm display. It runs continuously for about 90 minutes on a rechargeable lithium-based battery, enough to power the device for use on a typical eight-hour shift.

Click on image to enlarge.

"A lot of physicians see this and say, 'you've cracked the Holy Grail for the visual stethoscope,'" said Bartlett.