Department of Finemechanics, Graduate School of Engineering, Tohoku University, Sendai, Japan.
Skin Res Technol. 2024 May;30(5):e13740. doi: 10.1111/srt.13740.
The human nail has a three-layered structure. Although it would be useful to quantitatively evaluate the changes in deformability of the nail due to various surface treatments, few studies have been conducted.
The effects of two types of surface treatment-a chemically acting nail softener and a physically acting nail strengthener-on the deformability of human fingernails were investigated. The Young's modulus of each plate of the nail samples before and after softening treatment was determined by nanoindentation. The Young's modulus of the strengthener was determined by conducting a three-point bending test on a polyethylene sheet coated with the strengthener.
Young's modulus decreased in order from the top plate against the softening treatment time, and the structural elasticity for bending deformation (SEB) of the nail sample, which expresses the deformability against bending deformation independent of its external dimensions, decreased to 60% after 6 h of treatment. The Young's modulus of the nail strengthener was 244.5 MPa, which is less than 10% of the SEB of the nail. When the nail strengthener was applied to the nail surface, the SEB decreased to 73%, whereas the flexural rigidity increased to 117%.
Changes in nail deformability caused by various surface treatments for softening and hardening were quantitatively evaluated successfully.
人类的指甲具有三层结构。虽然定量评估指甲因各种表面处理而导致的变形能力变化会很有用，但目前此类研究较少。
研究了两种类型的表面处理方法——一种是化学作用的指甲软化剂，另一种是物理作用的指甲强化剂——对人手指甲变形能力的影响。通过纳米压痕法测定指甲软化处理前后各板的杨氏模量。通过对涂有强化剂的聚乙烯片进行三点弯曲试验，确定强化剂的杨氏模量。
指甲对软化处理的耐受力随处理时间的增加而逐渐降低，且指甲样本的弯曲变形结构弹性（SEB）值独立于其外部尺寸，在处理 6 小时后下降至 60%。指甲强化剂的杨氏模量为 244.5 MPa，不到指甲 SEB 的 10%。当指甲强化剂应用于指甲表面时，SEB 下降至 73%，而弯曲刚性增加至 117%。
成功定量评估了指甲因软化和硬化等各种表面处理而发生的变形能力变化。
