The evaluation of collagen architecture of the dermis in response to mechanical stimulation is important as it affects the macroscopic mechanical properties of the dermis. A detailed understanding of the processes involved in the alteration of the collagen structure is required to correlate the mechanical stimulation with tissue remodeling. This study investigated the effect of cyclic frequencies i.e. low (0.1 Hz), medium (2.0 Hz), and high (5.0 Hz) (physiological range) in the alteration of pig dermis collagen structure and its correlation with the macroscopic mechanical response of the dermis. The assessment of the collagen structure of virgin and mechanical tested specimens at tropocollagen, collagen fibril, and fiber level was performed using Fourier-transform infrared-attenuated total reflection (FTIR-ATR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) respectively. After 10³ cycles, a significantly higher alteration in collagen structure with discrete plastic-type damage was found for low frequency. This frequency dependent alteration of the collagen structure was found in correlation with the dermis macroscopic response. The value of inelastic strain, stress softening, damage parameter (reduction in elastic modulus), and reduction in energy dissipation were observed significantly large for slow frequency. A power-law based empirical relations, as a function of frequency and number of cycles, were proposed to predict the value of inelastic strain and damage parameter. This study also suggests that hierarchical structural response against the mechanical stimulation is time-dependent rather than cycle-dependent, may affect the tissue remodeling.

响应于机械刺激的真皮胶原蛋白结构的评估很重要，因为它会影响真皮的宏观机械性能。为了使机械刺激与组织重塑相关，需要对胶原结构改变所涉及的过程有详细的了解。这项研究调查了循环频率（低（0.1 Hz），中（2.0 Hz）和高（5.0 Hz）（生理范围））对猪真皮胶原蛋白结构变化的影响及其与真皮宏观机械反应的关系。使用傅里叶变换红外衰减全反射（FTIR-ATR），原子力显微镜（AFM）对原胶原和机械试样的胶原结构，原胶原，胶原原纤维和纤维水平进行评估，和扫描电子显微镜（SEM）。10点以后^在3个周期中，发现低频的胶原结构的改变明显更高，具有离散的塑料型损伤。发现胶原蛋白结构的这种频率依赖性改变与真皮宏观反应相关。对于慢频率，观察到非弹性应变，应力软化，损伤参数（弹性模量降低）和能量耗散降低的值显着增大。提出了基于幂律的经验关系，作为频率和循环次数的函数，以预测非弹性应变和损伤参数的值。这项研究还表明，针对机械刺激的分层结构响应是时间依赖性的，而不是周期依赖性的，可能会影响组织的重塑。