Softness sensor system for simultaneously measuring the mechanical properties of superficial skin layer and whole skin.
OBJECTIVE
Few attempts have been made to distinguish the softness of different skin layers, though specific measurement of the superficial layer would be useful for evaluating the emollient effect of cosmetics and for diagnosis of skin diseases.


METHODS
We developed a sensor probe consisting of a piezoelectric tactile sensor and a load cell. To evaluate it, we firstly measured silicone rubber samples with different softness. Then, it was applied to human forearm skin before and after tape-stripping. A VapoMeter and skin-surface hygrometer were used to confirm removal of the stratum corneum. A Cutometer was used to obtain conventional softness data for comparison.


CONCLUSIONS
Both the piezoelectric tactile sensor and the load cell could measure the softness of silicone rubber samples, but the piezoelectric tactile sensor was more sensitive than the load cell when the reaction force of the measured sample was under 100 mN in response to a 2-mm indentation. For human skin in vivo, transepidermal water loss and skin conductance were significantly changed after tape-stripping, confirming removal of the stratum corneum. The piezoelectric tactile sensor detected a significant change after tape-stripping, whereas the load cell did not. Thus, the piezoelectric tactile sensor can detect changes of mechanical properties at the skin surface. The load cell data were in agreement with Cutometer measurements, which showed no change in representative skin elasticity parameters after tape-stripping. These results indicate that our sensor can simultaneously measure the mechanical properties of the superficial skin layer and whole skin.
Shiseido Research Center, Yokohama, Japan. masashi.nakatani@gmail.com
Masashi
M
Nakatani
Toru
T
Fukuda
Naomi
N
Arakawa
Tomoyuki
T
Kawasoe
Sadao
S
Omata
D001696:Biomechanical Phenomena / Q000502:physiology; D003358:Cosmetics; D004548:Elasticity / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods; D004817:Epidermis / Q000293:injuries / Q000502:physiology*; D004867:Equipment Design; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D011312:Pressure; D012828:Silicones; D012879:Skin Physiological Phenomena; D053832:Surgical Tape / Q000009:adverse effects; D014110:Touch; D016474:Weight-Bearing / Q000502:physiology
D003358:Cosmetics; D012828:Silicones