The line separating human from machine got a bit fuzzier last month, when Google finalized two patents for smart contact lenses designed to alert people with diabetes to potentially dangerous dips in blood sugar levels. Around the same time, scientists at the University of Louisville helped three people with complete lower limb paralysis move their legs and feet by stimulating electronic devices they’d embedded in their spinal cords. And earlier this year, doctors implanted a chip in the brain of a man with complete paralysis that allowed him to move objects with his mind with the help of a prosthesis.
These medical marvels are entrancing, but helping restore lost function is only the beginning of the potential uses for implantable technology. When the able-bodied start merging tools with their bodies, is there even a line between man and machine to consider?
Implantable technology began in earnest in the late 1970s, after high school student Nan Davis was in a car crash that left her paralyzed from the rib cage down. In an effort to jumpstart the neurons in the muscles that had gone dormant after her crash, doctors glued dozens of electrodes to Davis’ legs and began sending pulses of electricity through them. The technique, called functional electrical stimulation (FES), worked, and after five years of therapy, Davis was able to stand up and walk for short distances. But every time she wanted to use her legs, Davis had to have a handful of electrodes glued to her skin (and later, painfully removed). Each electrode also had to be hooked up to the cumbersome electricity-generating machine via a tangle of wires.
“It was basically the opposite of a user-friendly or a viable approach for a person,” says Case Western Reserve University professor of rehabilitation engineering P. Hunter Peckham, who created the modern version of the system that first enabled Davis to walk.
Rather than having to be carted around, the new system developed by Peckham resides permanently inside a user’s body. It consists of a matchbox-sized electric stimulator—basically the system’s central computer—and a handful of smaller devices called peripherals that stimulate muscle and record sensation in whatever area of the body they are implanted. A peripheral in the hand, for example, would help someone grasp objects, while one embedded in the bladder would tell its user when to use the restroom.
While FES can help people with lower-level spinal cord injury, it cannot restore function to those whose spinal cords have been damaged closer to the base of the neck. In those types of injuries, the connective tissue linking the brain and the central nervous system is severed, making any movement virtually impossible. So scientists came up with a chip that, when implanted in the brain, allows people to move objects with their thoughts—no muscles required. In 2012, Cathy Hutchinson, who had been unable to move her arms or legs for 15 years after suffering a stroke, used the technology, known as brain-wave communication, to drink her morning coffee.
How does brain-wave communication work? It takes advantage of the fact that every time we think about moving specific parts of our body, our brains emit a unique electromagnetic pattern. Scientists implant a dime-sized sensor covered with electrodes in a patient’s brain. The sensor can read this pattern, similar to the way a smartphone might read a QR code, and translate it into a command sent to an external computer that powers a robotic arm or leg.
For now, the technology still has limitations. FES and brain-wave communication require neurosurgery. And only a few doctors at specialty centers scattered across the U.S. can perform these procedures, meaning that even if surgery is successful, a patient will need to return to the center for follow-ups or an emergency treatment.
“We have to build an infrastructure that allows for the basic support and maintenance of these devices that are embedded in people,” says Weill Cornell Medical College professor of medical ethics Joseph Fins. “These devices should be liberating, not tethering.”
Peckham and Brown University neuroscientist John Donoghue, who often discuss their work, see their devices as two elements that will one day allow someone with paralysis to function as an able-bodied person.
Some hobbyists aren’t waiting around for embeddable technology to mature and are taking it into their own hands—literally. Tech enthusiast Amal Graafrstra recently convinced doctors to place a tiny electronic chip known as a radio-frequency identification device (RFID) under the skin of each of his hands between thumb and forefinger. The rice grain-sized tags contain a unique identification number, which Graafstra linked to an external database. Now, when Graafstra wants to open the door to his home or car, or log onto his computer, or start his motorcycle, he just waves his hand in front of an RFID sensor that recognizes his chip.
Some useful electronic enhancements are more removable. A team of researchers at the University of California, San Diego recently devised an electronic tattoo that helps the wearer monitor his or her hydration levels during a workout. The tattoo, no bigger than a postage stamp, contains a sodium sensor and is connected to a wireless, Bluetooth-enabled device that can be worn on an armband similar to one made for a jogger’s iPod or mp3 player.
While the technology is still experimental, the goal of the tattoo is to provide its wearer with continuous information about his or her health, says the tattoo’s developer, UCSD bioengineer Joe Wang.
“It’s minimally invasive. It’s easy. I definitely see a future for technology like this,” he says.
Looking for an even more in-depth preview of the future of implantable technology? Joseph Fins, P. Hunter Peckham, and John Donoghue joined Paralympian Jennifer French at Better, Stronger, Faster: The Future of the Bionic Body, part of the Big Ideas Series at the 2014 World Science Festival.