Could a robotic exoskeleton turn you into a real-life Iron Man?

Then came the Iron Man movies, bringing a flood of publicity for Ekso, which was portrayed in the press as a real-life analogue to Stark Industries. “Now people are finally starting to see utility in these devices,” Angold says. “The tone has changed from ‘it’s impossible’ to ‘it’s inevitable.’”

That was great for business, but it also led to some outsize expectations. Suffice it to say that Ekso’s suits don’t come equipped with an arc reactor. But the movie did get one thing right, Angold says: “It’s all about the power supply. Without that power supply, Iron Man doesn’t work.”

Power woes have in fact doomed some companies’ ambitious exoskeleton efforts. Raytheon’s ballyhooed Sarcos XOS 2 lost its funding in part because it had to be plugged in to work, rendering it useless in the field. One early Ekso idea assumed a gas-powered engine, Angold says. When he ran it by his brother, a Navy SEAL, he laughed at the implausibility. “That pushed us to find a fundamentally different way to power exoskeletons and make them more efficient.”

The solution: mimicking the structure and movement of the human body, which conserves energy remarkably well, especially when at rest. Minimalism is also key—the HULC forgoes luxuries like arms or headgear, which makes it not much of a Hulk by Hollywood standards. But it still has funding.

Ekso and its kin appear likely to succeed as medical devices. The barriers are convenience and cost—the Ekso will start at a hefty $110,000—but those seem surmountable. Argo’s version is under $70,000, and Parker Hannifin is aiming for a similar price point and a weight of just 27 pounds. All of those figures should come down over time. And the inconvenience is a small price to pay for people like Woo to be able to stand up and walk across a room again.

Exoskeletons’ future in war and the workplace is less secure. Lockheed has yet to find a killer military app for the HULC, whose strength enhancements come at the cost of agility. The most plausible use for the time being is to help people carry or unload heavy equipment at a forward operating base where you can’t drive a truck or a forklift.

Likewise, anyone expecting Utah State’s Spider-Man suit to give them powers akin to those of the comic book superhero are in for some sore disappointment. It’s useful for one thing: climbing a wall, which it does loudly and slowly, making it less than ideal for a covert operation. The same goes for suits that let you race a fighter jet, beat up a grizzly bear, or even sense danger from behind. You wouldn’t want to walk around in any of them.

How long will it be, I asked Angold, before we have a more Hollywood-ready exoskeleton, one that lets you run faster, jump higher, and move boulders, all while fitting comfortably under your clothes for daily wear? He thought for a moment. “You know, we could make exoskeletons today to enable people to run faster. We could make ones today that fit under your clothes. All these things, we can do today. But I don’t think you can do all of them at the same time.”

Read more from this series: Human enhancement is giving us superpowers once reserved for comic-book heroes; technology is expanding our minds; brain-computer interfaces let you  move things with a thought; and choose your own sixth sense.