Bionics man offers a taste of our cyborg future

New Scientist, 29 July 2015

The next generation of bionic devices will be connected to their human users in a seamless and profound way, says prosthetics pioneer Hugh Herr

Credit: Chris Crisman

Credit: Chris Crisman

Tell me about your bionic legs…
I have a company that produces what I’m wearing: the BiOM Ankle System. For the first time in history we’ve normalised walking speed and its energy cost. In other words, if you simply measure a user’s speed and metabolic energy expenditure, you can’t tell whether they have bionic legs or biological legs. That’s especially important because conventional technology used on people with leg amputation makes them limp, which causes musculoskeletal stresses that lead to joint disease and many other secondary conditions. True limb bionics eliminate limping and solve these very costly secondary conditions. Typically when we fit the BiOM prosthesis to a person, if they have hip pain, knee pain or back pain it is reduced in days.

Could such bionics benefit people in general?
Actually, we have developed bionic technology for people with complete biological limbs. Last year, we were the first research group to build an autonomous leg exoskeleton that significantly reduces the metabolic cost of walking to a person without a leg condition. It’s an artificial calf muscle, which supplies about 80 per cent of the power to walk. So a person with a normal physiology could put on these exoskeletons and walk using substantially less energy.

It’s so profound in its augmentation that if you wear it just for 20 minutes and take it off, your legs feel heavy and awkward.

Who do you see using these?
Soldiers, hikers, athletes, anyone. Imagine a world where our physicality doesn’t decrease as we age. The number one reason your grandparents can’t get around is knee osteoarthritis, and the biomechanical cause is believed to be a degradation of calf muscle power. With bionics, we can put 18-year-old calf muscles in (or on) everyone, regardless of their age, and potentially solve this big mobility problem in the elderly. If our biology continues to have the typical age-related degeneration, bionic technology can make up the differential.

The best marathon time of your life could be when you’re 60, after you started running marathons when you were 20. Imagine how such future technology will affect running times, jumping heights and all types of athletic performances.

Isn’t it cheating to use technology like that?
The idea here is to use technology to maintain a human’s inherent biological physicality, a notion that most people would accept. One can imagine a world where people wear bionics just so that when they run and train they don’t have enormous stresses on their biological joints. We are clueless about our own bodies. We have no idea when we’re about to injure ourselves. Sensors in the machines can give us that awareness and tell us that we need to stop or do something different – or they can lower the physical stress for us.

Tell me about your vision to connect bionic devices directly to the human nervous system.
Prostheses and exoskeletons are conventionally controlled by electrodes on the skin that detect the electrical activity of muscles. But this approach is kind of a laboratory trick, with limited functionality for clinical applications. One reason is that if I left here and ran two miles, I could fill a whole glass with my sweat. Current skin-surface interfaces will not survive, or produce consistent signals, in such a harsh environment. So our goal is to get information in and out of the peripheral nervous system in a more direct manner – invasively.

Aren’t other groups are already doing this, by implanting electrodes directly into nerves?
The problem with approaches that pierce the nerve is that nerves complain loudly. It’s just not a viable, sustainable option in my view.

So what’s your solution?
What we are discovering is that you don’t need to pierce the nerve, because the peripheral system is remarkably flexible. If you take a muscle that doesn’t have a nerve and then you place a cut nerve close to that muscle, the nerve will grow and sprout and innervate the muscle. It’s a very robust and repeatable phenomenon. So we are creating an interface that exploits biology by growing nervous tissue through or around synthetic materials, closing the loop between human and machine. The interface would detect nerve signals that reveal a user’s intent to move a prosthesis, for example, or could transmit sensory information from a prosthesis into the body through the nerve.