Sliding Test by Using an Apparatus Imitating a Human Finger for Estimating the Tactile Sensation of Cosmetic Foundation

Abstract

When we acquire tactile sensation, contact and relative motion are necessary between our bodies and objects. This implies that the tactile sensation is produced by friction phenomena. The present paper describes the sliding test for estimating the tactile sensation associated with cosmetic foundation. When the cosmetic foundation is rubbed with an apparatus that imitates a human finger, two types of time-evolving signals -normal and tangential -are obtained as the source of the tactile information. In the sliding test with the apparatus under the frictional condition of humans acquiring the tactile sensation, frictional vibration is observed in the tangential signals, which should be related to the tactile sensation associated with the cosmetic foundation. When a surface with a grooved pattern that imitates fingerprints is used in the sliding test, two types of frictional vibrations are observed. If an adequate sliding velocity is selected, the slight difference between the four types of commercial cosmetic foundations is discriminable by using the signals of these vibrations.

Relationship Between Tactile Sensation and Friction Signals in Cosmetic Foundation

“…Moreover, several differences were found among the signals of different samples, e.g., the maximum value of the spring deflection and the amplitude of the frictioninduced vibration. It should be noted that these are the same tendencies as those seen in the application of commercial cosmetic foundation [20]. Figure 4 shows examples of the friction signals with and without samples A, H, and I acquired in ST2, where the lower surface moved in the X-direction for approximately 1.5 s from 0 s. Without a sample, the characteristics of the signal in ST2 were the same as those in ST1, since the experimental conditions were identical.…”

“…In ST2, we used the same flat plate for the lower surface, but applied a sample to the upper surface. In ST3, to simulate a fingerprint, we used a lower surface with rectangular grooves perpendicular to the sliding direction [20]; the pitch and depth of the grooves were 0.4 and 0.1 mm, respectively, and a sample was applied to it.…”

“…Tactile technologies are also required in the cosmetics industry, since the tactile sensation inherent in a cosmetic product is an important factor in perceived product value [15][16][17][18][19][20]. Cosmetic foundation is one such product; basically, it is a visualization-based product, but users like to achieve tactile comfort during its application.…”

“…Based on the findings of previous studies [1,20], a tribometer has been developed to simulate the friction phenomena that occur when human fingers are rubbed together, in an attempt to acquire the tactile sensation inherent in applying cosmetic foundation. It utilizes silicone-rubber surfaces that have compliance comparable to that of human fingerpads; they are lubricated by 10 types of samples simulating cosmetic foundation, consisting of plate-like particles, spherical particles, and silicone oil.…”

Fundamental study on the quantification of tactile sensation

“…This can be attributed to nonvolatile components remaining on the skin surface. On the other hand, some samples of Type F showed a periodic variation of the friction coefficient caused by the stick‐slip phenomenon [8], which resulted in a large MMD; this can impede finger sliding and affect sensory values. These results show that both MIU and MMD may affect tactile sensations.…”