Scanadu’s medical device is about two inches wide and a half-inch thick. When held to the forehead, it can measure oxygen intake, breathing and heart rate.

When Walter De Brouwer puts his head to something, he can produce single-handedly what usually takes several hospital machines and labs. His single hand, it should be said, holds a small and promising device with which Mr. De Brouwer, the co-founder and chief executive of Scanadu, hopes to remake medicine.

The object Scanadu is working on is an oval disk about two inches wide and a half-inch thick. Held to the forehead, it uses light to measure oxygen intake, an accelerometer to figure out how far the chest extends in breathing, and a small electrical plate under the thumb to measure heart rate. Other sensors, some still in development, will measure temperature, blood pressure and other body functions.

In some cases the sensors are taking direct measurements, including some from a mild circuit that is created by the loop of the arm to the forehead and through the body, which the device reads and sends to a smartphone app. Still others are planned to deduce more information, using software that draws from among the different measurements.

The Scanadu device is a long way from perfect, despite having been through a significant revision since it was first announced to some hoopla (the “Star Trek” tricorder comparisons came fast) a year ago. In an informal test, it first got my heart rate 60 beats per minute above what it had been in a doctor’s office a week before. A few moments later, it seemed absolutely accurate.

And that, in a sense, is part of the point. Rather than taking the rigorous and expensive approach usually applied to medical devices, Scanadu works like a software company. It creates a product, then toys with it, improving the software and tweaking the algorithms. Eventually, both theory and experience show, a product can become pretty good.

“It’s all off-the-shelf stuff,” Mr. De Brouwer said. His Mountain View, Calif., company hopes to have the device available as a mass market consumer product in late 2014, for about $199. “It’s the algorithms that are new.”

Mr. De Brouwer, a well-known tech entrepreneur, sees the device as only a part of his ultimate goal. “Everyone who comes into a hospital is so powerless,” he said. “Why don’t we have our own devices, so we can create and take our own data about ourselves?” Once we do, he figures, we can share and pool the data for novel research in a kind of homemade medical hackathon.

Walter De Brouwer, the founder and chief executive of Scanadu, demonstrating his company’s device.

Scanadu gained notice when it raised $1.6 million on Indiegogo, the crowdfunding website. Of the 8,800 people who gave money to the project, he says, some 1,100 were medical professionals (mostly doctors and nurses) in the United States. These contributors will soon receive an early version of the device, and their experience with it will go into further improving the product. Since then the company has picked up another $10.5 million in funding.

Scanadu has one of consumer tech’s more somber creation histories. Mr. De Brouwer, who is originally from Belgium, made a fortune during the first Internet boom, then lost much of it in the crash. He was earning the money back with a financial institution he purchased in 2003, when his son, then 4 years old, fell about 40 feet, landing head first on a concrete pavement.

The child was in a coma for 11 weeks, and eventually lost half of his brain; he is now in a school in California. Mr. De Brouwer spent a year inside a Belgian hospital, looking after his son and learning how to interpret a large number of medical machines. “I didn’t know anything about medicine ”” what a child’s blood pressure should be, what oxygenation was, what any of the displays said or how they worked,” he said.

Eventually he figured most of them out, and asked an administrator in the hospital’s information technology department where all the data was consolidated for collective analysis. “He told me that everything was stored 1:1; it didn’t get compared,” he said. “To someone from the tech world, this was like something from the dinosaur age.”

Mr. De Brouwer hopes not just to sell the device, but also to create a substantial body of people willing to store and share complex medical readings over a long period, measuring effects like stress and heart rates. He’s also running a “wet lab,” which is looking into a similar test system for urine and saliva.

That could produce both personalized medicine and a kind of collective information about the relationships between, say, respiration, temperature and oxygen intake before the onset of a disease.

The product still needs approval from the Food and Drug Administration, which will look at how people use the device and whether it is safe for individual use. Scripps Translational Science Institute will also be doing a study, drawn from the Indiegogo contributors, on the accuracy of the device.