How far off are scientists from developing human exoskeletons?

From Aliens to Iron Man, movies and TV have featured ability-enhancing suits for years. Steven Cutts asks whether reality will be catching up to science fiction in the near future

Tougher stuff: some companies want to use exoskeletons to mitigate workplace injury (Getty/iStock)

Since the beginning of time, humans have been disappointed by our own frailty. Our bodies are just too prone to falling, crushing or strangulation. Everything from magic potions to medieval suits of armour have been tried to address this problem and in the last few decades, the idea of some fundamental advance in human strength has finally become possible.

Like a lot of modern ideas, it first came to prominence on the big screen. In Aliens, Sigourney Weaver manages to find one of the hydraulically powered exoskeletons, just before the Acheron Queen alien tries to take a bite out of her friend Newt. Ordinarily, hand-to-hand combat with xenomorphs is the kind of thing I like to advise people against, but if you can get the right equipment, you’re in with a sporting chance.

James Cameron’s Aliens was released in 1986 and he seems to have been so enamoured with the idea of a mechanical device amplifying a person’s physical strength that he gave it even more onscreen time in 2009’s Avatar.

The idea of a human being controlling a more powerful suit or exoskeleton was already well established in the science fiction genre. For example, it served as the basis for the hugely popular Six Million Dollar Man series in the 1970s. But like flying taxis and hoverboards, the exoskeleton has struggled to escape from the lab and into the outside world.

Sigourney Weaver’s character Ellen Ripley wearing an exoskeleton P-5000 work loader (Alamy)

Part of that struggle is how it is powered. One type of exoskeleton currently being manufactured uses the body’s own mechanical movement and is described as a “passive system”. Another type augments human strength using electrically powered actuators or hydraulic levers to move the limbs. Compressed air is a potential power source, although the user would have to haul around their own air cylinder, which would then need changing or repressurising when empty.

Whatever angle you look at it from, energy is difficult to store and carry around with you. Steve Austin in The Six Million Dollar Man had a nuclear power pack in his left arm, always on standby to fuel his next bionic run. Whilst this was useful for the writers, they did little to explain how it actually worked.

Batteries are, of course, a more realistic solution, but as the makers of electric vehicles and aircraft have discovered, they are heavy as well as expensive. Not only that, they don’t actually store an awful lot of energy and need to be regularly recharged. And all of this is before we even look at the environmental impact. One way around the problem of batteries is to attach umbilical cables and pipes that trail a worker around a warehouse or factory floor, supplying them with power.

Iron Man character Tony Stark has a nuclear reactor located in his chest: a convenient device for writers but not a device that can realistically be made (Marvel)

Not surprisingly, the Pentagon has taken a keen interest in this kind of technology. The idea of an army of supermen all equipped with their own exoskeletons must be a very attractive one. But the same obstacles remain: battlefield-ready outfits potentially need an active energy source. Iron Man character Tony Stark has a nuclear reactor located in his chest: another convenient device for the writers but not a device that can be made.

Using present-day batteries, a soldier might expect to lose their superhuman strength very abruptly in no man’s land. Mobile recharging stations on the battlefield would have to be considered.

Passive enhancements are already seen in the kind of prostheses that are used by modern Paralympians. Usain Bolt won the 100m sprint at the London 2012 Olympics in 9.6 seconds. A few weeks later Jonnie Peacock, a below-knee amputee, finished the same run in 10.9 seconds. The loss of one half of a limb seems to have cost him only about a second over a distance of 100 metres.

One of the fundamental challenges of exoskeleton research is how we persuade a mechanical system to respond to the desires of the person who wears that system

Some modern exoskeleton devices promise to increase the productivity of people working in the construction industry and reduce the rate of industrial injury. This kind of technology doesn’t come cheap and if you want a company to buy into the concept, you’re going to have to convince them that it will save money elsewhere.

Workplace injury has been identified as a significant and important challenge for construction workers in the United States. American construction companies pay billions every year in compensation. Investment in a system that reduces the rate of industrial injuries might well be seen as a bargain by comparison. Furthermore, older workers may be able to stay in the workforce for longer because of the help provided by exoskeletons.

Jonnie Peacock won gold at the 2012 and 2016 Summer Paralympics, representing Great Britain in the men’s 100m event (Getty)

The American aerospace company Lockheed Martin has developed a passive exoskeleton system – named FORTIS – which is aimed at manual workers, particularly those holding heavy devices above shoulder height. The system transfers weight away from the worker’s own skeleton and onto an external frame that is worn around the legs and waist. Already in widespread use, FORTIS is the industrial application of Lockheed Martin’s previous research to assist soldiers in carrying heavy equipment over long distances, which resulted in their ONYX exoskeleton.

In Britain there are several research groups currently working on exoskeleton science, looking for both an application and a model that is not prohibitively expensive. Heba Lankany leads a research group at Liverpool University that is working with the Stoke Mandeville Spinal Cord Injury Unit. There is potential for a prosthesis to assist with upper limb movement, possibly in children with chronic muscle wasting conditions such as spinal muscular atrophy (SMA).

The priority here is in achieving an affordable design, as the existing systems are far too expensive for many patients to afford. Self-contracting synthetic muscle is now a reality and may ultimately represent a lower-cost substitute for conventional electromechanical actuators, but this is still at an early stage of development.

Lockheed Martin’s FORTIS exoskeleton could help mitigate many industrial injuries by making heavy power tools seem weightless (Lockheed Martin)

One of the fundamental challenges of exoskeleton research is how we persuade a mechanical system to respond to the desires of the person who wears that system. Some designs, known as myoelectric, pick up on the user’s muscle activity, such as electricity generated by muscle from a remaining limb, and then translate that into control of the prosthesis.

Another design tries to detect functions within the brain – effectively reading the mind’s intention to move – via the electrical activity in the prefrontal cortex. Lankany has been studying both options and is currently developing a myoelectric prototype system for possible use in helping patients with weakened limbs move around.

Robert Bloomfield, a British-based entrepreneur who has worked with the engineering department in Leeds University, has developed some prototypes in this field himself. In the long term he is sceptical as to how far exoskeletons can take us. Yes, they are already in use and are still evolving, but at least some of the applications that have been proposed for this technology are likely to remain in the realm of science fiction.

Like a lot of tech developers, during the pandemic Bloomfield struggled to secure funding. One group of people who this didn’t seem to impact were those sponsored by the United States government.

An exoskeleton created by Spanish company Able Human Motion is demonstrated (AFP/Getty)

The US Marine Corps have looked at helping marines arm helicopters or aircraft in war zones. The work often involves lifting heavy ordnance above shoulder height and holding it there until the missile has been suitably secured to the aircraft. With the help of passive or active exoskeleton technology, it may be possible to arm the aircraft more quickly and with a potentially smaller group of workers.

Such advancements seem to justify the significant funds that the Pentagon has already put into exoskeleton research. But no matter how good your understanding of biomechanics, you’re still going to be constrained by the energy density of your batteries, by the strength-to-weight ratio of existing materials and the overall load of the kit you’re carrying.

Researchers are making progress in all of these areas, but like flying cars and self-driving taxis, this kind of tech remains agonisingly one step short of final credibility. So, how far off are scientists from developing human exoskeletons? The answer is some are already here and in use, but if you’re hoping to get your hands on a fully functioning Tony Stark suit, you might be in for a bit of a wait.