Abstract
Elevated skin temperature at the body/device interface of lower-limb prostheses is one of the major factors that affect tissue health. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the hard socket and liner material employed. However, monitoring of the interface temperature at skin level in lower-limb prosthesis is notoriously complicated. This is due to the flexible nature of the interface liners used which requires consistent positioning of sensors during donning and doffing. Predicting the residual limb temperature by monitoring the temperature between socket and liner rather than skin and liner could be an important step in alleviating complaints on increased temperature and perspiration in prosthetic sockets. To predict the residual limb temperature, a machine learning algorithm – Gaussian processes is employed, which utilizes the thermal time constant values of commonly used socket and liner materials. This Letter highlights the relevance of thermal time constant of prosthetic materials in Gaussian processes technique which would be useful in addressing the challenge of non-invasively monitoring the residual limb skin temperature. With the introduction of thermal time constant, the model can be optimised and generalised for a given prosthetic setup, thereby making the predictions more reliable.
Highlights
Increased heat and perspiration is a common complaint of many amputees
The results indicated that the heat transfers through prosthetic materials in a logarithmic fashion – initially with a fast rate of heat transfer which decreases as time increases – and reaches a steady state at a temperature lower than that of the heating tape temperature
It becomes all the more imperative to build in the existing Gaussian processes for machine learning (GPML) model the thermal time constant so obtained from the thermal studies
Summary
Increased heat and perspiration is a common complaint of many amputees. Hagberg and Branemark [1] found that a significant percentage (72%) of their study population (transfemoral amputees, n = 95) reported the problem of heat/ sweating as their most common complaint. The properties of prosthetic sockets create an environment, where this heat transfer is influenced by the insulating properties of commonly used socket materials and liners These materials inhibit the body’s ability to radiate heat effectively [7] and may be a cause of the reported thermal discomfort mentioned early. Before the problem of thermal discomfort can be tackled, further investigation into the thermal properties of prosthetic materials is first required This will assist in the further understanding of prosthetic materials and enable clinicians to identify the materials which are the least effective in transferring the heat radiating from the human body to the outside environment. This would especially be useful in addressing the challenge of noninvasively monitoring the residual limb skin temperature for a wider amputee population
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