An image of the helmet design produced by Intellectual Ventures. (Courtesy image/U.S. Patent Office)

The most prolific inventor of all time and Bill Gates walked into a room in 2014 in Bellevue, Wash., with another 19 researchers and creators. They called it an “invention session,” and their objective was straightforward: Build a better football helmet.

Among the cast: Gates, drawn to the project out of his friendship with Seattle Seahawks owner Paul Allen; Lowell Wood, the aforementioned inventor and an astrophysicist with more patents to his name than Thomas Edison; Danny Hillis, an innovator who once described his super computer as “a machine that will be proud of us.”

A successful patent could potentially have unlocked football’s $500 million future of helmets with sensors that detect concussion-causing hits. Its creators would be able to cash in on a future of helmets designed individually for each player’s unique biomechanics.

But there was a problem: Not even Gates and Wood and the 19 others could figure out how to build a helmet that truly solves the issue at hand. A helmet that measures the force of a hit has limited utility, but one that can measure the impact that hit has on a player’s brain could change the sport.

“This technology is pretty solid at clearly measuring the forces on the helmet, but they’re not measuring the forces on your brain,” said Geoff Manley, chief of neurosurgery at Zuckerberg San Francisco General Hospital and co-director of the Brain and Spinal Injury Center at the University of California-San Francisco. “Just measuring the forces outside the cranium doesn’t give you an accurate picture of what’s going on inside your head.”

A study published in March in the Journal of Athletic Training found that “head-impact-monitoring systems have limited clinical utility due to error rates, designs, and low specificity in predicting concussive injury.”

After eight hours, the team of inventors, brought together by global inventions firm Intellectual Ventures, produced a helmet with sensors embedded in the interior lining to detect forces exerted upon the wearer. It had a transmitter near the base of the helmet to send a signal to the sideline when the wearer should be checked for injury. It featured alert devices such as sirens or flashing lights, according to a patent published in October.

It was a promising design, according to football equipment experts, but it still probably will not achieve the goal of accurately detecting concussions.

The reason so many major players are pursuing this invention is because it has the potential to fulfill the future helmet companies envision: an era when players will wear specifically fitted helmets for their position, head structure and the way their brains each react to linear and angular force, according to Thad Ide, the senior vice president for research and product development for sports equipment company Riddell.

“There will come a day when you won’t be able to buy a football helmet like you find right now without all that instrumentation and tuned for the individual player,” he said.

That has some major financial upside, industry observers say. Imagine a youth football player returning to the same company to purchase a new helmet every season as they grow, or having their helmet reconditioned based on individual biomechanical factors.

“There’s a tremendous economic opportunity here,” said Steve Fainaru, an investigative reporter for ESPN and author of the book “League of Denial” about the NFL’s campaign to down play the long-term impacts of traumatic brain injuries.

And under the right circumstances, football’s most important client is already interested. The NFL in the 2013 and 2014 seasons conducted a voluntary pilot program with sensored helmets, but scrapped it in 2015 because the data was too inconsistent, said Sean Sansiveri, the business and legal vice president for the NFL Players Association, the league’s labor union.

“Our position is to follow the science,” he said. “I think it has promise, but it’s something that folks haven’t figured out yet.”

Helmet design — a hard shell to prevent skull fractures and face mask to stop broken noses and teeth — generally has not changed sinced the 1950s.

Sensor technology has. Accelerometers in the early 2000s were so expensive, it cost up to $75,000 to outfit a football team with instrumented gear. Football teams couldn’t afford that investment; only universities or research centers could.

But in the era of the iPhone and the dawn of self-driving cars and artificial intelligence, sensors are everywhere.

Football helmet companies have picked them up and have now turned to the commercial market, selling their products, such as impact-monitoring helmets, mouth guards and skin patches, directly to teams or individual players.

Football’s protective equipment has gotten so good, there’s not much for sporting good companies to improve anymore outside the skull, said Jeff Carbeck, the specialist leader for advanced materials and manufacturing at Deloitte. The unchartered business territory is inside the skull, and the product that can accurately monitor head impact forces and concussion risk would be marketable to football players, sure, but also soccer players and rugby players, and even the military. But manufacturers have yet to crack the code for such a product.

“It’s a little bit of the wild west right now,” said David Camarillo, assistant professor of bioengineering at Stanford. His lab is working on a force-measurement mouth guard. “Most of these businesses, as far as I can tell, it’s been kind of a grave yard. A lot of these businesses don’t make it.”

That hasn’t deterred larger business interests, though, from putting more stock in sensors in football gear. Almost every major football equipment manufacturing company works with instrumented helmets.

Intellectual Ventures spent a year filing a patent for its helmet and has now reached the early stages of evaluating its future. The company will either license the design to a manufacturer, spin off a company to commercialize it or shelve the idea if it lacks promise. That process takes a long time, said Jeremy Salesin, Intellectual Ventures’ vice president of acquisitions. The company has yet to make a prototype for testing.

“We don’t know exactly how it’s going to function,” he said, “but we hear there’s a need.”