A new research could enable amputees who use a prosthesis to experience pain again. A special skin-like material has the ability to transmit pain to the brain. Pieces of the synthetic skin on the mechanical hand’s thumb and index finger. (Image via John Hopkins School of Medicine)
Several situations can affect someone’s health and wellbeing, but some of those circumstances can bring the person to lose a limb or two or just part of a limb. When that happens, in many cases, a prosthetic limb is often the solution to give the patient his or her mobility back. The challenge with the artificial limbs is that their design doesn’t permit that the patient feels any sensations. But recently, researchers of the John Hopkins School of Medicine invented an artificial hand that will allow the user to feel pain. The secret of this prosthetic hand is the artificial skin that makes up the outer layer of the hand.
It might be questionable why pain is the sensation that the researchers wanted to mimic with their new discovery, but it turns out pain is essential for the brain to recognize a potentially dangerous object or situation. Luke Osborn, one of the Biomedical Engineering graduate students of the John Hopkins University and co-author of the research, explained that without the ability to feel pain, a prosthesis could be damaged or destroyed; luckily, the artificial skin doesn’t just provide the prosthesis the sensation of pain but is engineered in a way that the user’s brain can understand the sensation as well.
Fruit of the collaboration between Osborn and Nitish Thakor, a neuro-engineer from the same university, the artificial skin transmits touch and pain to the brain through an electric nerve stimulator implanted above the prosthesis, in the arm. The signals the brain receives are very similar to the type it would receive in real-time pain-inducing circumstances. To achieve that the researchers modeled the transmission of electric messages between the nerve endings in a normal dermis and the brain receptors. During the testing phase, the volunteer who is an amputee confirmed that at the touch of objects, he could distinguish the round ones from the edgy ones. However, the volunteer rated the pain level at a 3 out of 10 on the scale of the least severe to the most severe. In other words, he could feel it but not in a way that was uncomfortable.
The e-dermis system block diagram. (Image via Osborn 2018)
As much as pain can damage the human body, the absence of it can negatively alter the artificial pieces of body someone wears. But the similarities don’t stop there. While the consequences of pain can cost tens of thousands in medical treatments, no pain sensation for a prosthesis also leads to a high cost of repair. Talk about life’s irony. The very sensation that could lead to someone losing his limbs is the same sensation that could keep that person alive. Furthermore, a prosthetic limb that can feel touch and other sensations are the ultimate replacement for a body part. It will take autonomy to the next level for the user by giving him extra control. Even more interesting is the switch off feature of the mechanism. Users can turn off the function that identifies pain and still experience sensations, thanks to the built-in reflexes that activate automatically.
Now, the question is how reliable and valid the study is. After all, there is no point in giving hope to people especially when there is nothing or nobody to back the research. Luckily, Osborn and Thakor not only have the support of John Hopkins University but also that of Sharlene Fletcher, a postdoctoral researcher from Stanford University who read the report on the new study and found, as a more experienced researcher, that their methodology and results are very consistent for the most part. She explains that there are aspects of the testing phase that were unnecessary like measuring the brain’s reaction to a stimulus (EEG); she argued that the electroencephalogram doesn’t indicate the location on the body that is being stimulated, but only the way the brain is reacting to the stimulation. Regardless of the discrepancy, she believes that their research could serve as stepping stone for better prostheses in the future.
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