Healthcare monitoring at your fingertips: validation of a smartphone alternative to routine measures of skin sensibility

The capacity to perceive tactile input at the fingertips, referred to as tactile sensibility, is known to diminish with age due to regressive changes to mechanoreceptor density and morphology. Sensibility is measured as perceptual responses to stimuli of varying intensity. Contrary to traditional sensibility monitoring instruments, smartphones are uniquely suited for remote assessment and have shown to deliver highly calibrated stimuli along a broad spectrum of intensity, which may improve test reliability. The aim of this study was to evaluate a vibration-emitting smartphone application, the Vibratus App, as a mode of estimating tactile sensory thresholds in the aging adult. The peripheral nerve function of 40 neurologically healthy volunteers (ages 18–71) was measured using monofilaments, a 128-Hz tuning fork, the Vibratus App, and nerve conduction studies (NCS). Between group differences were analyzed to determine each measurement’s sensitivity to age. Spearman correlation coefficients depicted the associative strength between hand-held measurements and sensory nerve action potential (SNAP) amplitude. Inter-rater reliability of traditional instruments and the software-operated smartphone were assessed by intraclass correlation coefficient (ICC 2, k ). Measurements taken with Vibratus App were sensitive to the age-related decline in tactile sensitivity (t(30.643) = -3.480, p = .002). The inter-rater reliability of smartphone and tuning fork testing was moderate (ICC 2,k = 0.57 and 0.51, respectively), whereas monofilament testing was good (ICC 2,k = 0.83). The findings of this study support further investigation of smartphones as remote tactile sensitivity monitoring devices.