Biotribology of the ageing skin—why we should care

Ageing of populations has emerged as one of the most pressing societal, economic and healthcare challenges currently facing most nations across the globe. The ageing process itself results in degradation of physiological functions and biophysical properties of organs and tissues, and more particularly those of the skin. Moreover, in both developed and emerging economies, population ageing parallels concerning increases in lifestyle-associated conditions such as Type 2 diabetes, obesity and skin cancers. When considered together, these demographic trends call for even greater urgency to find clinical and engineering solutions for the numerous age-related deficits in skin function. From a tribological perspective, detrimental alterations of skin biophysical properties with age have fundamental consequences on how one interacts with the body's inner and outer environments. This stems from the fact that, besides being the largest organ of the human body, and also nearly covering its entirety, the skin is a multifunctional interface which mediates these interactions. The aim of this paper is to present a focused review to discuss some of the consequences of skin ageing from the viewpoint of biotribology, and their implications on health, well-being and human activities. Current and future research questions/challenges associated with biotribology of the ageing skin are outlined. They provide the background and motivation for identifying future lines of research that could be taken up by the biotribology and biophysics communities

Biomedical Applications of Wrinkling Polymers

Advancements in surface engineering and material fabrication techniques have enabled the creation and replication of naturally occurring surface topographies or the extrapolation of natural patterns to become achievable targets. Polymers are used extensively in the field of biomedical sciences for containment, handling, and as cell culture substrates. It is well established that several polymers exhibit good biocompatibility for cell culture, with properties that include exhibiting minimal to no cytotoxicity and being sufficiently hydrophilic to facilitate cell adhesion. However, when using biologically representative materials, there is always a challenge of achieving tissue representative surface topography and architecture. Wrinkles in human skin represent a considerably common surface topography, resulting from aging and maturity of the tissue. Inspired by this natural topography, the present review article discusses the various techniques for generating wrinkle-like patterns on the polymer surfaces, along with their potential biomedical applications. Wrinkling as material science and as a physical concept has been explored only during the last century. The transfer of the knowledge related to wrinkling from hard engineering materials to soft elastomers has resulted in the development of an active research field, although it remains in its infancy in terms of application in biomedical science and engineering. It is suggested that wrinkling of polymers, particularly elastomers, would have numerous applications, ranging from tissue modeling in drug and therapy design to in vitro organogenesis for therapeutic explants in the field of regenerative medicine

Biomedical Applications of Wrinkling Polymers

Advancements in surface engineering and material fabrication techniques have enabled the creation and replication of naturally occurring surface topographies or the extrapolation of natural patterns to become achievable targets. Polymers are used extensively in the field of biomedical sciences for containment, handling, and as cell culture substrates. It is well established that several polymers exhibit good biocompatibility for cell culture, with properties that include exhibiting minimal to no cytotoxicity and being sufficiently hydrophilic to facilitate cell adhesion. However, when using biologically representative materials, there is always a challenge of achieving tissue representative surface topography and architecture. Wrinkles in human skin represent a considerably common surface topography, resulting from aging and maturity of the tissue. Inspired by this natural topography, the present review article discusses the various techniques for generating wrinkle-like patterns on the polymer surfaces, along with their potential biomedical applications. Wrinkling as material science and as a physical concept has been explored only during the last century. The transfer of the knowledge related to wrinkling from hard engineering materials to soft elastomers has resulted in the development of an active research field, although it remains in its infancy in terms of application in biomedical science and engineering. It is suggested that wrinkling of polymers, particularly elastomers, would have numerous applications, ranging from tissue modeling in drug and therapy design to in vitro organogenesis for therapeutic explants in the field of regenerative medicine

Friction Between Human Skin and Incontinence Pads in the Presence of Topical Barrier Protection Treatments

This research project investigated skin friction in relation to skin damage in the skin-pad interface, which is relevant to those living with incontinence, as well as professionals in the medical community who seek to treat the condition. This is a common and debilitating skin condition, and the tribological behaviours of skin treatments for this condition are not well understood. An initial experimental study focussed on developing protocols to understand the properties of skin in an untreated and treated state. The results gave insights into skin hydration, roughness, deformation, and friction. This study evidenced the suitability of the protocols for in vivo testing, and highlighted relationships between skin moisture and stratum corneum roughness, moisture and friction, and deformation and friction. With the addition of skin treatments, it was found that glycerol and Vaseline both considerably increased the friction coefficient, whereas Cavilon did not. Cavilon also produced a more consistent friction response across all participants. In addition, it identified that Cavilon, an advanced formulation developed specifically to protect skin of those with incontinence, performed differently to glycerol and Vaseline. To put the experimental studies into context an online questionnaire was designed to reach a community of people living with incontinence to learn about their experiences of incontinence-associated dermatitis (IAD). Knowledge was gained into various management techniques, including choice of treatments and absorbent products. User-defined data about the skin-pad interface was collected, such as incontinence severity, symptoms of IAD, and bodily locations affected. The dataset helped to establish factors that impacted the severity levels of IAD, which aided in the development of a new question based diagnostic tool to categorise people according to the severity of IAD that they experienced. If made available for public use in the future, it could play a role in the early stages of diagnosis. The protocol from the first experimental study was adapted to assess tribological interactions in the skin-pad interface, with IAD specific skin treatments and different wetness conditions. In a wet-pad state Cavilon reduced friction, and had much lower dynamic and static coefficients of friction than the other barrier treatments (Sorbaderm Barrier Cream and the barrier spray). Cavilon provided stable friction coefficients in reciprocating sliding, whereas the other treatments, and untreated skin, did not display this unique characteristic. The barrier spray gave rise to high static friction coefficients, and exhibited the most stick-slip. Cavilon, Sorbaderm, and the barrier spray were all found to reduce directional differences in the static coefficient of friction; indicative of reduced shear loading. A number of strategies were identified by which skin protection can be realised. Recommendations applicable for use by clinicians and those living with incontinence to form part of a preventative management regime for IAD, with the hope of improving the lives of those living with incontinence

Pressure Ulcer prediction using ADT

Objective : To develop a prediction model for pressure ulcer cases that continue to occur at an acute care hospital with a low occurrence rate of pressure ulcers. Methods : Analyzing data were collected from patients hospitalized at Tokushima University Hospital during 2012 using an alternating decision tree (ADT) data mining method. Results : The ADT-based analysis revealed transfer activity, operation time, and low body mass index (BMI) as important factors for predicting pressure ulcer development. Discussion : Among the factors identified, only “transfer activity” can be modified by nursing intervention. While shear force and friction are known to lead to pressure ulcers, transfer activity has not been identified as such. Our results suggest that transfer activities creating shear force and friction correlate with pressure ulcer development. The ADT algorithm was effective in determining prediction factors, especially for highly imbalanced data. Our three stumps ADT yielded accuracy, sensitivity, and specificity values of 72.1%±3.7%, 79.3%±18.1%, and 72.1%±3.8%, respectively. Conclusion : Transfer activity, identified as an interventional factor, can be modified through nursing interventions to prevent pressure ulcer formation. The ADT method was effective in identifying factors within largely imbalanced data

An experimental study of friction between wet and dry human skin and nonwoven fabrics

Many people who have urinary incontinence manage it with the use of absorbent hygiene products, such as pads. Long-term use of these products can lead to abrasion by friction between the topsheet (a nonwoven fabric) and the skin, and is exacerbated when the skin is wet. However, the nature and mechanisms of friction between skin and nonwovens are poorly understood, hindering progress to improve products. Most work on skin friction to date has involved the use of skin surrogates or real skin in the dry state only. Moreover, only a narrow range of different nonwoven fabrics have been investigated. The work described in this thesis aimed to improve understanding of friction between nonwoven fabrics and human skin, and was divided into four main blocks. In the first, friction was measured between a skin surrogate (Lorica Soft) and 13 different nonwoven fabrics, varying in structure, fibre material and manufacturing techniques. Amontons’ law was closely obeyed for all nonwovens (that is, coefficients of friction were independent of normal force) and the data were used to select a representative subset of five nonwovens for subsequent work. In the second block of work, an in vivo study of friction was conducted between the subset of (five) nonwovens and the dry volar forearm skin of 19 female volunteers (aged 20-95 years). It was found that Amontons’ law also held for all of these measurements, despite the general viscoelastic nature of human skin, the range of skin types (from smooth and firm to wrinkled and flaccid) and the difference in ages. The coefficient of friction for a given fabric varied considerably between participants (an increase of up to 101% of the lowest coefficient value), but the fabrics were generally ranked in the same order for all volunteers. The third block of work involved the measurement of wet friction between the subset of five nonwovens and volar forearm skin of five of the study participants. In general, the coefficient of friction increased with skin wetness/hydration by up to a factor of thirteen until the skin was damp/moist. The relationship for very wet skin (with surface water) – thought to be lubricated – was unclear and varied between participants and between nonwovens. However, further work would be required to locate and quantify the excess water in and on the skin, in order to more accurately evaluate the contribution of water to friction. Finally, in the fourth block of work, the fibre footprints of nonwovens against a surrogate skin surface (glass microscope slide) were examined, providing insight into how friction is mediated by the interface. Total fibre contact length was always extremely low (typically 0.3-1.6 mm · mm-2) and increased linearly with the log of pressure, usually due to an increase in the number of contacts and sometimes because of an increase in the lengths of existing fibre contacts

DEVELOPMENT OF A WHEELCHAIR CUSHION COVER WITH MICROCLIMATE MANAGEMENT TO PREVENT PRESSURE INJURIES

Pressure injuries are a common medical problem that negatively influences mortality, causes financial burdens, and reduces quality of life for people with spinal cord injuries or other mobility impairments. Wheelchair seat cushion designs are developed to reduce risk factors for pressure injuries. Pressure, shear and friction are the primary causative factors known to increase pressure injury risk. Other factors include heat and moisture. Current preventive approaches related to seat cushions focus on reducing pressure, shear, and friction. The important heat and moisture factors are seemingly overlooked. Options to manage microclimate at the support surface interface are limited. This study aims to develop a wheelchair cushion cover, which provides currently available wheelchair cushions with an advanced feature to improve microclimate management by reducing heat and moisture at the body-seat interface to help prevent pressure injuries. The development of the wheelchair cushion cover with microclimate management included the following steps: generating a design specification, developing three design concepts, fabricating a prototype, evaluating the cover and conducting focus group interviews. The prototype cover was modeled on mattress low air loss features and its function was applied to wheelchair cushions. The cover was intended for use with the existing cushion and cover. Evaluation of the prototype cover was performed and focused on quantifying the microclimate control features. A thermodynamic rigid cushion loading indenter simulated the environmental conditions of a human body on three cushion types for 3-hour tests. Comparing results for the three cushions with and without the prototype cover demonstrated significantly lower relative humidity after 1 hour (p 0.002) was found for the entire test session. Standardized cushion characterization tests showed that the prototype cover provided additional pressure distribution (p < 0.002) compared to the three test cushions without the new cover. This study included focus group interviews to gather feedback regarding the prototype cover. The cover received an overall positive response from participants. All participants agreed with the utility of a microclimate management feature and necessity of the product. They would recommend the cover to wheelchair users