The Present and Future of Bionic Prosthetics

My first real exposure to prosthetics was, funnily enough, through video games. From shooting with nano-augmentations in Deus Ex to playing detective with Rhys’s cybernetic eye in the Borderlands series, it’s clear that the development of bionics plays an integral role in our everyday sci-fi fantasies. Now, more than ever, it seems like the present is catching up with the future. Just this year, leading prosthetics company OpenBionics released an entirely 3D-printed arm modeled on the iconic bionic arms from Deus Ex. But just how do these seemingly fantastical machines work?

Modern bionics operate by interfacing motor signals with rerouted nerves that connect to working muscles [1]. For example, patients with amputated arms undergo a complicated surgery that re-wires nerves from dead shoulder tissue to healthy chest muscle. Electrodes are then attached to the chest and connected to the bionic arm, which enables signals to be relayed from the brain to the bionic, causing it to move in the desired manner [2]. Bionics are currently capable of a quite a range of motions, including grasping, flexing, reaching, exerting, and rotating joints [1]. While we’re nowhere near being able to construct a Terminator, the advent of techniques such as 3D printing has helped propel the field over several obstacles, including those of cost, customization, and versatility.

So how does this impact the lives of actual patients? Bionic development always requires a high level of personalization. Prosthetics need to be molded specifically to the user, and must be adjusted constantly as their body changes and grows [3]. Fabricating bionics is expensive due to the specialized materials involved, and building a new one every few years would be difficult and costly [3]. However, using exoskeletons that are 3D printed can help resolve this problem as adjustments to larger specifications can be handled simply by printing additional layers onto the existing frame [4]. In this manner, the bionic can grow with the user instead of requiring a complete replacement [4]. This can provide a great economic advantage to patients in need of prosthetics. For example, OpenBionics’ 3D printed Hero Arm costs £5,000, compared to £60,000 alternatives that don’t use 3D printing [5]. Additionally, 3D printed bionics can also relieve patients of the inconvenience of being fitted with an entirely new bionic every few years, while also saving precious time and resources.

However, the applications of bionics extend beyond prosthetic limbs. More advanced prosthetics, such as cochlear implants—a neuroprosthetic device that aids in hearing—and bionic eyes have their own difficulties, the issue of size being particularly important. Due to the small scale of these systems and their complex workings, building electronics on such miniscule levels is a difficult feat. However, the versatility of 3D modelling allows us to overcome this challenge. By using a printer that prints layers in spaced-out intervals, newly printed machinery is given time to set into place before more layers can be printed on top [6]. This is highly useful when fabricating extremely fragile electronics, such as the components required for a bionic eye. In this case, devices that transduce light and effectively mimic photoreceptors must be layered onto a delicate hemispherical surface similar to that of a retina. 3D printing techniques are then used to allow scientists to layer phototransducing inks in a way that replicates the rods and cones of human eyes [6]. Using this method, scientists at the University of Minnesota have successfully created the first prototype of a bionic eye that currently works at a 25% efficiency in converting light into electric neural signals [6]. While much more research must be done before clinical trials can begin, Dr. McAlpine’s work holds a lot of promise in revolutionizing the world of prosthetics.

While the field of bionics is full of potential, the future still holds many challenges. Issues of not just technical, but also ethical nature must be addressed before progressing onwards. While they certainly haven’t progressed enough yet, bionics may one day be able to surpass the performance of our natural bodies. This is not a new concept; ever since the philosopher Julian Huxley coined the term in 1957, the “transhumanism” movement has considered the augmentation of human bodies by technological means[7]. And while the concept seems appealing in video games and movies, how would transhumanism really affect society as we know it? Would a world where we pay to have our bodies enhanced, instead of repaired, be a good place to live in?

Still, the advancement of bionics may open the door to an incredible future. In a world where bionics are widely implemented, the loss of a limb or other parts of the body can be easily remedied. Amputees and other patients might not have to settle for a life without the complete working function of their bodies. In any case, bionic development shows no sign of slowing. Only time will tell how it will change the world we know.  

Written by Rifaa Fatima Ali

References
  1. Marasco PD, Hebert HS, Sensinger JW, Shell CE, Schofield JS, Thumser ZC, et al. Illusory movement perception improves motor control for prosthetic hands. Science Translational Medicine. 2018;10(432):69-90. Available from: doi: 10.1126/scitranslmed.aao6990.
  2. Cheesborough JE, Smith JH, Kuiken TA, Dumanian GA. Targeted Muscle Reinnervation and Advanced Prosthetic Arms. Semin Plast Surg. 2015;29(1):62-72. Available from: doi: 10.1055/s-0035-1544166
  3. Mohney G. Health Care Costs for Boston Marathon Amputees Add Up Over Time. [Internet]. 2013 [cited 2018 Dec 18]. Available from: https://abcnews.go.com/Health/health-care-costs-boston-marathon-amputees-add-time/story?id=19035114
  4. FormLabs. Using 3D Printing to Manufacture Custom Prosthetics. [Internet]. 2017 [cited 2018 Dec 18]. Available from:  https://formlabs.com/blog/3d-printing-powered-startup-manufactures-affordable-custom-prosthetics/
  5. Hobbs A. Open Bionics’ releases affordable 3D printed bionic arm. [Internet]. 2018 [cited 2018 Dec 18]. Available from:  https://internetofbusiness.com/open-bionics-hero-arm/
  6. Hyun Park S, Su R, Jeong J, Guo SZ, Qui K, Joung D, et al. 3D printed polymer photodetectors. Advanced Materials. 2018;30(49):1-8. Available from: doi: 10.1002/adma.201803980.
  7. Hays SA. Transhumanism. [Internet]. 2018 [cited 2018 Dec 18]. Available from: https://www.britannica.com/topic/transhumanism.

 

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