This paper describes three series of tests that were designed to investigate how skin mechanical and structural properties, measured using a ‘Cutometer’ and optical coherence tomography, affect the frictional behaviour of human finger-pads. First, the skin mechanical properties across all fingers and the palm in participants’ dominant hands were assessed. Results showed that the distensibility of skin (total deformation in a suction test) is associated with stratum corneum thickness and that this in turn affects friction (thicker stratum corneum leads to higher friction), giving a link between distensibility and friction. Tape stripping to remove the superficial layer of the skin led to increased moisture (and/or electric charge on the skin surface) that led to higher friction. No accompanying changes were seen in structural properties, so it was concluded that moisture was the main cause of the adhesion increase. More work is required to isolate moisture and possible changes in electric charge using alternative measurement techniques. When rubbing with sand-paper, the stratum corneum thinned considerably and friction reduced. Moisture was ruled out as a cause of friction changes in this instance. Skin normal stiffness also did not change, but lateral stiffness changes have been seen in previous work when the stratum corneum thickness has been reduced, so this is likely to be the cause of the reduced friction. This will be investigated further in future work using dynamic optical coherence tomography measurements.

Three-dimensional interconnected carbon nanofibrous mats containing well-dispersed MoO_2+δ nanocrystals are fabricated through electrospinning for high-performance Li-ion battery anodes.

Studies on the variation of skin properties with gender, age and anatomical region, with regards to interaction with different materials have resulted in significant research output. Investigations on skin surface strain and sub-surface layer deformation during sliding, however, have not received as much attention. This novel study uses two non-invasive techniques, optical coherence tomography (OCT) and digital image correlation (DIC), to measure properties of the index finger of a 25<!-- --> <!-- -->year old female when under normal and shear loading. Measurements were taken during static, and for the first time, dynamic phases. It was observed that the number of ridges in contact with a Quartz glass surface, observed under OCT, reduced when the finger started sliding. The sliding also resulted in deformation at the stratum corneum junction. The surface strain, analysed using DIC was higher nearer to the distal interphalangeal joint compared to the fingertip. This newly developed approach provides a powerful and non-invasive method to study the structural changes of finger-pad skin during loading and sliding. This approach can now be repeated at different anatomical locations for medical, bioengineering and consumer applications.