Computational analysis of the relationship between mechanical state and mechanoreceptor responses during scanning of a textured surface

Abstract

Skin deformation caused by contact with an object is transduced into nerve signals by tactile mechanoreceptors, allowing humans to perceive tactile information. Previous research has revealed that the mechanical state associated with finger skin deformation at mechanoreceptor locations in a finite element model is correlated with the experimentally measured responses of slowly adapting type I mechanoreceptors. However, these findings were obtained under static contact conditions. Therefore, in this study, we calculated the von Mises stress at slowly adapting type I and rapidly adapting type I mechanoreceptor locations during dynamic scanning of a textured surface using a finite element model of the human finger. We then estimated the hypothetical responses of the mechanoreceptors and compared the estimated results with the nerve firing of the receptors in previous neurophysiological experiments. These comparisons demonstrated that the temporal history of von Mises stress at mechanoreceptor locations was more strongly correlated with the “number of” impulses (R2 = 0.93 for slowly adapting type I and R2 = 0.90 for rapidly adapting type I) than the impulse “rate” (R2 = 0.58 for slowly adapting type I and R2 = 0.53 for rapidly adapting type I). Our findings suggest that the temporal history of von Mises stress can be used to roughly estimate the number of impulses of mechanoreceptors during scanning of a textured surface.

The effect of contact pressure on photoplethysmography

“…This paper defined the ratio of normalized pulsation intensity at 660 nm and 940 nm as (18): 𝐼 = 𝑃(660 𝑛𝑚) 𝑃(940 𝑛𝑚) (18) commercial pulse oximeters are typically calibrated in a blood oxygen saturation range of 70 to 100% [43]. The empirical calibration curve of the commerical pluse oximeter is denoted by the formula about ratio I, expressed as (19):…”