Skin quality sensor to evaluate vibration and friction generated when sliding over skins

Area of Science:

• Biomedical Engineering
• Materials Science
• Dermatology

Background:

• Skin tactile evaluation is crucial for skincare product development.
• Existing instruments primarily assess skin hardness or use imaging, with limited focus on rubbing motion.
• There is a need for instrumental methods to quantify tactile sensations during skin rubbing.

Purpose of the Study:

• To develop a novel sensor for measuring tactile sensations and contact phenomena during skin rubbing.
• To assess the sensor's ability to measure vibration and friction simultaneously.
• To validate the sensor's performance against existing instruments and sensory evaluations.

Main Methods:

• A hand-held sensor with rotating metal probes, an accelerometer, and a force sensor was developed.
• The sensor measures vibration and friction during automated rubbing of the skin.
• Validation involved measuring artificial skin models, comparing results with commercial sensors, surface roughness, and sensory evaluations, and assessing inter-rater reliability.

Main Results:

• The developed sensor showed high correlation (r=0.99) with a tri-axial acceleration sensor for vibration intensity.
• Vibration intensity correlated strongly with surface roughness (r=0.91) and sensory evaluation (r=0.99).
• Friction coefficient measurements correlated well with a force plate (r=0.93), and inter-rater reliability was high (0.92-0.94).

Conclusions:

• The developed sensor accurately measures skin vibration and friction, comparable to conventional methods.
• High inter-rater reliability indicates consistent and dependable measurements.
• The sensor is a valuable tool for tactile evaluation in the development of skin care products.