Temperature-Dependent Dynamic Friction of a Single Human Corneocyte at Nanoscale Contact: An Analytical Approach and...

Area of Science:

• Tribology
• Biophysics
• Nanotechnology

Background:

• Dynamic friction between human skin and surfaces rises with temperature, potentially causing damage.
• The nanoscale friction of human skin cells at varying temperatures is not well understood.

Purpose of the Study:

• To quantify the dynamic friction of human skin corneocytes at the nanoscale as a function of temperature.
• To investigate the relationship between temperature, sliding velocity, and friction at the skin-nanoprobe interface.

Main Methods:

• Utilized atomic force microscopy (AFM) with a heated tip and lateral force microscopy (LFM).
• Measured dynamic friction of corneocytes under a 10 nN normal load and 40% relative humidity.
• Calibrated tip temperature and compared experimental data with an analytical friction model.

Main Results:

• Dynamic friction increased exponentially with sliding velocity as AFM tip temperature rose.
• The rate of friction increase diminished at very high sliding velocities.
• Friction behavior differed significantly between low (<35 °C) and high (>35 °C) temperatures.

Conclusions:

• Nanoscale skin friction is highly sensitive to temperature and sliding velocity.
• At low temperatures, friction increases with velocity; at higher temperatures, skin hydration may lead to lubrication.