The University of Southampton

Author: Emma Stone

Sensors in Prosthetics

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Following a brief introduction in our lectures to sensors and prosthetics, I was inspired to learn more. Like many people, I had never considered all the limitations that affect prostheses users. I wanted to see how sensors could help make bionic limbs work as well as human limbs.

Controlling prostheses

In lectures we learnt about electromyogram (EMG) sensors which are used to control prostheses. To find out more I spoke to an engineering student who has produced a low budget EMG sensor as part of his year 3 project.

Short interview on EMG – Picture sourced from Electrotherapy for MSP

Improving Touch

When I think of a prosthesis, I think of a replacement body part. However, as the human body is deeply complex with many integrated systems to allow us to survive and interact with our environment, prostheses simply do not have the same functionality as human limbs. One thing I thought about was the extent to which upper limp amputees can experience human touch and their surroundings through their prosthesis.

Excitingly, by using a MiniTouch device, which can be integrated into existing prosthetic limbs, thermosensitive prostheses can be produced. Experimentally this device has been successful at allowing the user to decipher between objects with different temperatures. This technology helps prosthesis users to sense human touch akin to the feeling we get through our fingertips and increases sensation to help with motor control. However, the complete sensation of human touch still cannot be experienced by the user as human touch is a lot more complex than heat. For example, thermal sensors cannot convey to the user the texture of another person’s skin, although I was pleased to learn researchers are making progress in the development of tactile sensors.

The MiniTouch device technology has been developed further here at the University of Southampton. Researchers helped prosthetic wearers feel ‘wetness’ so both dexterity and motor control can be improved.

Improving Grip

The Southampton tube sensor

Sensors can also be utilised to improve the dexterity of prostheses users by preventing objects being dropped. This can be achieved by detecting when a slip is occurring. One option for slip detection is shown here. I found the reuse of existing technology and use of simple parts fascinating. It is made from a hearing aid microphone within a tube in contact with the grip surface. Slippage results in vibration signals which are transmitted to the air within the tube and onto the microphone. Airborne noises and interference signals can be thresholded out.

Controlling Orthoses

Orthoses are like prostheses but are designed to improve the functionality of movable parts of the body. There are many uses including rehabilitation and assisting daily activities. The mPower 1000, for example, is a neuro-robotic arm brace that fits like a sleeve on a person’s arm. It has sensors that can detect even a very faint muscle signal and the mPower 1000 provides motorised assistance in response. It is intended to increase arm movement affected by neuro-logical conditions such as stroke, spinal cord injury, multiple sclerosis, cerebral palsy, muscular dystrophy, and traumatic brain injury. Ethically, I worry if orthoses are widely used by able bodied people, it could have an untold impact on society and potentially even lead to weaponisation of the human body.

My Final Thoughts

It is really important to continue developing tactile sensors so protheses can become more like human limbs. Researching this topic has changed my perspective as I now understand we are a long way from having prosthetics which work as well as natural limbs however there is a great deal of ongoing research to improve prosthetics.

The Burning Question About Stem Cells – Are they the best solution?

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Following the lectures on stem cells and tissue engineering, I was intrigued to learn how stem cells could be used in wound healing and specifically burn treatment. The use of stem cells for burn treatment would be amazing due to their ability to modulate the release of the chemokines, cytokines, and growth factors necessary for wound healing. Although I think this could be a really useful and interesting use of stem cells there are not yet published clinical trials on the efficacy of stem cells in burn wound care.

Pre-clinical trials have showed stem cells induce a significant promotion in healing rate of burn animals, compared with animals in control groups. Hair follicle stem cells (HFSCs) seem to be most effective at promoting the healing of burns. I was surprised to see that at this stage it appears autologous stem cells did not provide a significantly better therapeutic effect than either allogeneic or xenogenic stem cells, even though they could lead to an adverse immune reaction caused by graft-versus-host disease.

Mechanisms stem cells could use to achieve wound healing in burns.

During my research I was reminded of a storyline in one of my favourite TV shows Greys Anatomy where as part of an innovation competition one doctor was looking at the use of tilapia fish skin to help with the healing of burn wounds. I was interested in finding out whether this is a reality or just fiction. I quickly found an article on a phase III randomized controlled trial looking at the benefits of Nile tilapia fish skin-based wound dressing.

Severe burns are often life altering and are a leading cause of disability-adjusted life-years especially in developing countries, such as Brazil, which may not have public health systems that can provide modern dressings developed for treating burns. Use of talapia fish skin could improve access to an effective treatment of superficial partial-thickness burns by reducing the treatment-related costs. Currently most Brazilian burn units use silver sulfadiazine cream. This is used as silver ions are antimicrobial and importantly few bacteria have been shown to develop resistance to silver. However, it has been suggested that there might not be enough evidence to suggest that burns heal better when using silver sulphadiazine.

The phase 3 randomized control study (linked above) they compared the time taken for reepithelialization, cost-effectiveness and the pain occurring during treatment with silver sulfadiazine and talapia fish skin. The mean cost per patient and number of days to complete reepithelialization was lower when Nile tilapia fish skin was used. The use of tilapia fish skin showed a reduction of approximately 50.0 percent in the mean costs for each 1 percent total body surface area ($4 vs $8). Even better news was the fact there was also a statistically significant reduction in mean pain score with the talapia fish skin treatment. Therefore, I think this treatment is a fantastic innovation.

My thoughts

Although stem cells are a fascinating area of current research, their use in treatments will not necessarily be accessible in developing countries. Simple but successful innovative treatments like the use of talapia fish skin for healing will remain important in medical research.

Here’s a video I found of the first woman to receive this a talapia fish skin treatment.