Bending as Key Mechanism in the Tactile Perception of Fibrillar Surfaces

Abstract

The touching of fibrillar surfaces elicits a broad range of affective reactions, which range from the adverse stinginess of a stiff bristle brush to the pleasant feel of velvet. To study the tactile perception of model fibrillar surfaces, a unique set of samples carrying dense, regular arrays of cylindrical microfibrils with high aspect ratio made from different elastomer materials have been created. Fibril length and material compliance are varied independently such that their respective influence on tactile perception can be elucidated. This work finds that the tactile perception of similarity between samples is dominated by bending of the fibrils under sliding touch. The results demonstrate that variations of material stiffness and of surface structure are not necessarily perceived independently by touch. In the case of fibrillar elastomer surfaces, it is rather the ratio of fibril length and storage modulus which determines fibril bending and becomes the dominant tactile dimension. Visual access to the sample during tactile exploration improves the tactile perception of fibril bendability. Experiments with colored samples show a distraction by color in participants’ decisions regarding tactile similarity only for yellow samples of outstanding brightness.

MetaReality: enhancing tactile experiences using actuated 3D-printed metamaterials in Virtual Reality

“…As recent advancements of fabrication technologies support the manufacturing of highly detailed physical artifacts, they have been used to construct artifacts with varying haptic properties. Examples include methods for designing objects with desired mechanical behavior, such as elasticity or deformation through varying internal microstructures (Bickel et al, 2010;Schumacher et al, 2015), or for fabricating perceptually-varying surface texture qualities (Piovarči et al, 2016;Degraen et al, 2021b;Gedsun et al, 2022). Moreover, these approaches have been used in virtual settings to create tactile experiences through passive haptic proxies.…”

Controlling fine touch sensations with polymer tacticity and crystallinity

“…16 To study the role of friction in touch, tactile discrimination has been explored by controlling surface texture and asperities through micropatterning techniques. 18 Skedung et al used elastomers with patterned wrinkles formed by surface buckling to identify a minimum feature size of 13 nm for discriminating objects purely by surface roughness. 4 Sahli et al designed randomly rough 3-D printed surfaces with an average RMS value of 0.4 mm and varied the Hurst roughness exponent and topographic shape to probe the ability of humans to discriminate randomly rough surfaces.…”