“NATURE IS driving design,” Hugh Herr said, during his TED talk on bionics in 2014. As the head of the Biomechatronics* research group at the MIT Media Lab and also a double amputee, Herr gave the inspirational speech while wearing bionic legs he designed called the BiOM, the world’s first bionic ankle-foot system. His legs do not move stiffly, but rather display smooth walking and running movements mimicking those of a natural human limb. Along with such bionic technology, brain-computer interfaces (BCI) have also recently been developed, showing potential to help people with disabilities far better than before. With the help of BCI, which can deliver commands from the brain to a robotic arm or other devices connected to a paralyzed arm, people with limb loss or paralysis of the limbs could gain more independence in carrying out ordinary movements. Though such technology is not yet ready for widespread use, bionics and BCI are seen as promising fields that could help people restore, or even enhance, their physical and mental abilities. And, as both bionic bodies and BCI involve the connection between machines and human physiology, they may also change the way we perceive “humans.”
Like flesh and bone
As Herr explains in his talk, bionics “explores the interplay between biology and design.” That is, bionics applies findings from natural features and functions of the human body in making robotic prostheses, such as the BiOM. In the past, people with prostheses in place of a missing leg had to walk with crutches. Although traditional prostheses such as a wooden leg have a long history, they could not do more than physically take the place of a missing body part. With bionic technology, novel prostheses combined with computational intelligence can mimic the biological functions and movements of natural human biology. Bertolt Meyer, currently a professor at the Chemnitz University of Technology, wears a high-end bionic hand which can change grips with a simple gesture in place of his missing left hand.
According to Herr’s TED talk, the development of the BiOM entails the engineering of mechanical, dynamic, and electronic interfaces. A special synthetic skin mechanically attaches the bionic leg to the biological limb. After figuring out the geometries and locations of various tissues and measuring tissue compliances** at each anatomical point, the framework for the optimal synthetic skin is made. As for the dynamics of the bionic limb, analyzing the physiology of actual limbs is needed. By examining muscle movements of a biological leg – how they reduce shock on the limb at every step and how they propel the leg to lift its foot – BiOM was able to be equipped with adequate propulsion which other prosthetic legs do not have. The electronic interface deals with how the bionic limb interacts with the body’s nervous system. Electrodes on Herr’s residual limb measure the electrical pulse of his muscles and transmit it to the bionic limb. Embedded in the chips of the BiOM is an algorithm which modulates the reflex. Thus, the BiOM is able to respond to the neural signals of the residual limb.
Until recently, bionic prostheses did not necessarily involve direct connection to the brain. Before an upgrade in 2015, Meyer’s hand was able to perform 24 grip patterns, which had to be controlled via a mobile application; the BiOM operates independently from the brain, using an algorithm and microprocessors which control its movement. But further development in bionics is opening up possibilities for a bionic hand or leg to be controlled wirelessly by the brain. Meanwhile, some hope that 3D printing technology would make less high-end prostheses more available to people who need them.
Connecting to the brain
In recent years, there has been increasing research on invasive BCI and a number of studies have produced successful results. In May 2012, Nature published a study online which showed that people with longstanding paralysis could direct a robotic arm to perform certain movements such as raising up a bottle of coffee (as seen at the top of this page), using signals decoded from a sensor implanted in their brain’s motor cortex. More recently on April 13 this year, a research carried out at Ohio State University and Battelle Memorial Institute revealed that Ian Burkhart, who has been paralyzed for more than five years from the neck down due to a spinal cord injury, could move his hand to perform simple tasks such as holding a glass of water or swiping a credit card. This could be done similarly with the help of a chip implanted in Burkhart’s motor cortex, and a device worn on his arm which receives the signals from the chip and turns them into ones that his muscles can understand.When the concept of BCI first emerged, it usually referred to a non-invasive interface; rather than implanting electrodes directly in the brain, the interface was based on Electroencephalography***, or EEG.
According to Im Chang-hwan (Prof., Dept. of Biomedical Engin., Hanyang Univ.), the way invasive interfaces work could be likened to the process of fingerprint scans commonly used in biometrics. In order for fingerprint scans to work, a database of fingerprints is required. The database consists of the distinct “features” of each registered fingerprint. Then, when a certain person’s fingerprint is scanned, the features of the fingerprint are compared to the features stored in the database in order to find a match.
Likewise, in order for a BCI to work for a person with paralyzed arms, the person has to perform multiple motor imagery tasks; by imagining the performance of various movements, scientists can identify each movement with particular electrical signals decoded from a chip, or needle electrodes, implanted in the motor cortex. These signals make up the database for the BCI. Then, when the person intends to move his arm in a particular direction, the corresponding signals from the brain is decoded from the needle electrodes, and by comparing these signals with the ones registered in the database, the assistive device estimates the intended movement of the person and carries out the movement.
Such interfaces serve to connect commands from the brain with the body or an alternative assistive device such as a robotic arm. According to Chad Bouton, who led the research published on April 13 and is currently at the Feinstein Institute for Medical Research, people with full or partial paralysis due to spinal cord injury usually have intact signals from the brain’s motor cortex area, but cannot deliver these signals to the muscles because they get blocked at the injury of the spinal cord. After the computer deciphers, or decodes, the brain signals associated with movement, they are delivered to a robotic arm or a device connected to the person’s muscles, which then drives the commanded movement.
Im says that as the BCI technology is still incomplete, the current goal is to create prostheses that closely mimic the actual functionality of the human body. Once that is achieved, then technology would go on to exceed this functionality. However, BCI has expanded to other realms in which widespread use is already under way. Non-invasive BCI in the form of wearable devices that measure brain waves of the wearer – also referred to as “passive BCI” – can be used to analyze a person’s level of attention, emotional arousal, etc. and provide the person with adequate education or entertainment. According to Im, such technology is usually used in the treatment of patients with ADHD or social disorders. BCI can also be used by people who do not have disabilities. On April 22, the world’s first brain-drone race was held in the University of Florida, where participants wearing BCI devices on their heads controlled drones using only their brain waves, by thinking of navigating the drone.
Concerns, now skin-deep
Despite their potential to provide immense help to the disabled, many issues regarding bionics and BCI have yet to be solved. For example, with invasive BCI, the surgery of implanting needle electrodes in the brain has quite a high percentage of failure. The endurance of the sensor and the risk of infection are some of the concerns that still need to be addressed.
In addition, since the human brain is dynamic, brain signals that occur in a certain given situation may differ from person to person, and they may even change within a single person’s brain. Thus, the database for a BCI must be customized for each individual, and even after creating a complete database using mental imagery tasks, it may have to be complemented and modified each time it is used.
The long-term training that is required before using the BCI technology is another drawback. According to an article published in The Washington Post on April 13, “Burkhart tested and fine-tuned the system during up to three sessions a week for 15 months after the operation that implanted the chip in his brain’s motor cortex region.” This is a problem in the use of bionic limbs or hands as well. As for the current level of technology, constant communication between the device and wearer’s body is actually needed before the machine can perform naturally. Due to these unresolved technical concerns, BCI technology is not ready for commercial use. In a similar sense, though bionic devices are sold by several companies, they are still very expensive, making it inaccessible to the majority of the disabled.
On another note, developments in bionics and BCI have the potential to blur the line between what we perceive as humans and machines. Herr claims in his talk that not only will development in bionic technology go on to end disability, it will provide even non-disabled people with exoskeletal devices that greatly enhance walking and running movements – everyone will be wearing such devices in the future, for they will enable people to walk or run far more efficiently. If the future should be molded as Herr expects it to be, we would be stepping closer to an era of transhumanism.
Of course, this prospect points to a future which is quite far away. As Im put it, actually enhancing the capacities of the human brain using BCI is yet close to being “science-fictional.” Connecting a brain chip to the area of a damaged hippocampus, which deals with the forming, storing and processing of memory, makes it possible to transfer and store information read from the chip to a computer, and also to put in external information into the brain and store it as long term memory. According to Im, such an experiment has been conducted on mice and has seen success, but actual enhancement of human intelligence using BCI is not yet possible.
Nonetheless, it is most likely that the way we perceive disability will undergo a gradual change. As the comparatively novel field of bionics and BCI gain more speed in progress, advanced technology will continue to aid and go beyond our natural capacities. The likely consequence is that we will start to view everyone as disabled; it will get increasingly difficult to draw a clear distinction between illness and good health. As the line between restoration of weak or lost functions and enhancement of human biology becomes more and more ambiguous, an ethical consensus in the social and political sectors would be needed before engineers and companies push forward with the commercialization of these emerging technologies.
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Though the level of development in bionics and the biomedical engineering field is insufficient to provide effective aid at an affordable price to all people with disabilities, these fields indeed promise a revolutionary change for the lives of the disabled. However, as technology begins to surpass human nature, this is also when various concerns arise. In many instances, it is difficult for social debate and policy making processes to align with technological development. Thus, as the development of bionics and BCI moves forward, we must try to induce social consensus on both ethical and legal matters.
*Biomechatronics: An emerging field of technology that combines human physiology and electromechanics
**Compliance: The ability or process of yielding to changes in pressure without disruption of structure or function
***Electroencephalography (EEG): An electrophysiological monitoring method to record electrical activity of the brain, typically involving electrodes placed along the scalp