The University of Southampton

Author: Alex Lunika

Enhancing Functionality and Quality of Life in Upper Limb Prosthetics

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Introduction

Sensation is a crucial aspect of everyday life; it allows us to feel texture, pressure, and temperature of objects that we interact with.

Now imagine trying to pickup a delicate object without being able to feel it in your hand, how hard do you need to squeeze your fingers to hold it without the object falling out of your hand? Or are you gripping too hard that you might break it? This lack of sensory feedback is a major concern of prosthesis users and here we will explore the methods of sensory feedback.

Here is Dr. Ian Williams discussing developing a prosthesis with sensory feedback:

The role and history of sensory feedback for prosthesis users

The idea of restoring sensory feedback in prosthesis has been around since 1917 when Rosset patented a mechanism (Patent No. DE301108) that relays finger pressure via pneumatic or mechanical means. Many others followed, like the Vaduz prosthetic hand in the 1940s (Patent No. 2567066) which provided voluntary-closing hand and a “bladder” which was connected to the residual limb in the socket to provide force feedback. However, amputees still struggle with using these prosthetics as the user can’t tell what their prosthetic is doing without having to actively look or pay attention to what their prosthetic is doing. This is due to the lack of proprioception. (1)

Vaduz Hand, From Bulletin of Prosthetics Research, BPR 10-6, 1966.

Different types of sensory feedback

There are several methods that attempt to incorporate sensory feedback for upper limb prosthetics that try to provide users with sensory information. (1)

  • Electrostatic feedback
    • Electrostatic feedback involves the use of electrical signals to stimulate the skin and provide sensory feedback.
  • Mechanotactile feedback
    • Involves the use of mechanical pressure or vibrations to stimulate the skin and provide sensory feedback about the position and movement of the limb.
  • Sensory substitution
    • Involves providing sensory information through a different modality than the missing limb such as using visual or auditory feedback to replace the sense of touch in the hand.
  • Invasive feedback
    • Involves the use of implanted sensors to provide feedback about the prosthetic limb.

Additionally something else that needs to be taken into account is the time it takes for the feedback to reach the nervous system and be processed. Therefore, different feedback methods need to consider time delay when designing their systems. (2)

My insights and reflection

Sensory feedback plays a crucial role in bridging the gap between human limbs and artificial limbs. There are undeniable benefits in introducing sensory feedback in prosthesis such as enhanced functionality and improved quality of life including, providing a sense of proprioception to amputees. However, there are still several challenges faced in restoring sensation.

These include:

  • Expanding the range of sensations
    • Allowing the user to feel textures, temperature and also pain.
  • Personalisation and adaptability
    • Everyone is different and the ability to accommodate for a fit, growth and usage of the prosthesis is a huge challenge in meeting individual needs.
  • Affordability and accessibility
    • At this moment advanced prosthetics are prohibitively expensive and only a small handful of people around the world have the opportunity to have even basic sensory feedback.

An ethical and tricky question to consider is: Should we have artificial pain? This is a whole topic that could also lead to another post, but briefly, it has benefits for being a warning mechanism for potential harm, providing a realistic experience and better decision making. However ethical concerns arise if it is morally justifiable to subject users to distress, the level of pain intensity and how are you able to stimulate pain.

References

1.           Antfolk C, D’alonzo M, RosĂ©n B, Lundborg G, Sebelius F, Cipriani C. Sensory feedback in upper limb prosthetics. https://doi.org/101586/erd1268 [Internet]. 2014 Jan [cited 2023 Mar 24];10(1):45–54. Available from: https://www.tandfonline.com/doi/abs/10.1586/erd.12.68

2.           Sensinger JW, Dosen S. A Review of Sensory Feedback in Upper-Limb Prostheses From the Perspective of Human Motor Control. Front Neurosci. 2020 Jun 23;14:345.

The Ethics of Replacement Body Parts: Is It Ethical to Enhance Our Bodies?

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Medium.com

Recently I have been reviewing and watching content regarding our rapid advancements in technology which has given us the ability to replace body parts with prosthetics or other artificial devices. However, with this ability a significant ethical question arises of whether it is ethical to enhance our bodies beyond their natural capabilities. I drew inspiration for this post from the video by the Pew Research Centre included at the end.

One of the key ethical concerns surrounding replacement body parts is the question of what it means to be human. Humans have historically viewed themselves as distinct from other animals because of our unique combination of physical, emotional, and intellectual capacities. The introduction of artificial enhancements to our bodies could blur the lines of what it means to be human, and could even lead to the creation of new, non-human species. This raises important questions about how we define humanity, and what the implications of altering our bodies could be for our identity as humans.

ScientificAmerican.com

Another ethical issue that arises with replacement body parts is the potential for inequality. While the technology for artificial replacements has become more accessible in recent years, it still remains out of reach for many people, particularly those in less developed countries or who do not have access to proper healthcare. If only a select few individuals are able to afford or access these enhancements, it could lead to a new form of inequality where those who can enhance their bodies are more advantaged than those who cannot.

There is also the concern that replacement body parts could become a form of social pressure. If certain enhancements become popular or even necessary to keep up with societal norms, it could create an environment where people feel pressured to modify their bodies even if they do not want to. This could lead to a lack of individual autonomy and could even be seen as a form of discrimination against those who choose not to enhance their bodies.

However, there are also arguments in favour of replacement body parts and enhancing our bodies. One of the primary benefits is the ability to improve the quality of life for individuals who have experienced physical limitations due to injury or illness. By replacing a lost limb or enhancing an impaired sense, individuals can regain their independence and improve their overall well-being.

Archive Photos//Getty Images

Additionally, the development of replacement body parts has the potential to drive medical innovation forward. The same technology used to create prosthetics and artificial enhancements could also be used to develop new treatments for a variety of medical conditions however it would inevitably also be used military purposes as well.

To summarise the ethics of replacement body parts and the idea of enhancing our bodies is a complex issue with no easy answers. While there are certainly concerns about the potential implications of modifying our bodies, there are also clear benefits to individuals and society as a whole. As we continue to advance in technology and medical innovation, it will be important to carefully consider the ethical implications of these advancements and to work towards a future where everyone has access to these life-changing technologies.

Introduction

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Hi, I am Alex I study Biomedical Science and this is my first blog post.

I picked this module because I am really interested in medical engineering and to get an understanding of how body parts are replaced and produced. I am interested in particular in bionics where artificial limbs and organs are able to replace existing organs and limbs. I find it very fascinating that modern bionics and artificial limbs are becoming more and more advanced to match organic body parts and even in some instances becoming superior to organic body parts. For example an article I have read in the past discussing whether a person might actually favour an artificial limb over their current legs to gain an advantage for rock climbing as a artificial legs has shown to give an advantage in grip and reach that they never had before. I want to learn more about what are the regulations and current state of development of engineering and designing

Here below is a video showcasing how biophysicist Hugh Herr developed his replacement legs.