Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.
J Mech Behav Biomed Mater. 2012 Mar;7:60-8. doi: 10.1016/j.jmbbm.2011.05.027. Epub 2011 May 25.
Agar is a biological polymer, frequently used in tissue engineering research; due to its consistency, controllable size, and concentration-based properties, it often serves as a representative material for actual biological tissues. In this study, nanoindentation was used to characterize both the time-independent and time-dependent response of agar samples having various concentrations (0.5%-5.0% by weight). Quasi-static indentation was performed at different loads and depths using both open- and closed-loop controls. Reduced modulus (Er) values change with agar concentration, ranging from ∼30 kPa for 0.5% samples to ∼700 kPa for 5.0% samples, which is the same modulus range as usually encountered in soft biological materials. Dynamic indentation was performed to assess the effects of load, dynamic frequency and amplitude. Storage modulus values ranged from approximately 30 to 2300 kPa depending on agar concentration. Loss modulus remained consistently less than 30 kPa at all conditions, indicating a diminished damping response in agar.
琼脂是一种生物聚合物，常用于组织工程研究；由于其一致性、可控制的大小和浓度依赖性特性，它经常作为实际生物组织的代表性材料。在这项研究中，使用纳米压痕技术来表征具有不同浓度（重量比为 0.5%-5.0%）的琼脂样品的无时间依赖性和时间依赖性响应。使用开环和闭环控制在不同的载荷和深度下进行准静态压痕。降低的模量（Er）值随琼脂浓度而变化，范围从 0.5%样品的约 30 kPa 到 5.0%样品的约 700 kPa，这与通常在软生物材料中遇到的模量范围相同。进行动态压痕以评估载荷、动态频率和振幅的影响。存储模量值根据琼脂浓度在大约 30 到 2300 kPa 之间变化。在所有条件下，损耗模量始终保持在 30 kPa 以下，表明琼脂的阻尼响应降低。
