犬离体心肌应力-应变关系超声印压方法研究

目的：探讨超声循环印压检测心肌被动力学属性可行性，为活体检测提供基础。方法：通过循环印压犬离体心室肌，获得印压力和心肌形变实验数据。结果：以准线性粘弹性理论（QLV）模型处理所获得的应力、应变数据，获取左心室心尖和游离壁心肌被动力学属性参数A、B、C、D、E，两者的参数比较无差异（P〉0.05）。结论：介入超声循环印压检测心肌被动力学属性是可行的。可望在话体检测不同状态下舒张期心肌被动力学属性，进一步从力学机制层面深入认识舒张性心力衰竭。     

活体生物软组织力学特性研究的现状

活体生物软组织力学特性的研究，属于生物粘弹性固体力学的研究范畴，有别于离体研究的特点是它注重综合考虑活体状态下神经和体液等因素对被测组织力学特性的影响。这是近些年来应用研究，特别是临床应用研究的需要而发展起来的，本着重介绍近年来有关活体状态下，研究生物软组织力学特性的新方法、新技术和新发明的试验装置，以及所取得的结果与应用价值。     

生物软组织力学特性二维动态测试系统的研究

本文简述了生物软组织力学特性二维动态测试系统的设计。通过测量作用在软组织上的外力及软组织的形变,反映软组织力学特性。并以兔子腹部皮肤为对象,用本测试系统测量其滞后、松驰、蠕变特性,验证了本系统的可行性。     

生物软组织力学特性的研究进展

本文对生物软组织力学本构关系的研究进展进行了综述,内容涉及肌肉、韧带、肌腱、皮肤、粘膜、血管、腔体器官(如眼球)等领域.     

猪的软组织超声背向散射的初步研究

本文探讨了超声背向散射系数的测量原理,在远场测量的情况下推导出了由平均背向散射传递函数求平均背向散射系数的一般公式,报道了我们已建立的背向散射测量系统及利用此系统对一些动物软组织样品所作的测量结果。     

活体生物软组织力学特性研究的现状

活体生物软组织力学特性的研究，属于生物粘弹性固体力学的研究范畴，有别于离体研究的特点是它注重综合考虑活体状态下神经和体液等因素对被测组织力学特性的影响。这是近些年来应用研究，特别是临床应用研究的需要而发展起来的。本文着重介绍近年来有关活体状态下，研究生物软组织力学特性的新方法、新技术和新发明的试验装置，以及所取得的结果与应用价值。     

体表软组织肿块超声诊断价值的研究

目的探讨高频彩超在诊断体表软组织肿块中的诊断价值。方法对我院79例经病理证实的体表软组织肿块患者的超声检查结果进行回顾性分析。结果79例体表性肿块包括10种病变,69例良性病变,10例恶性病变。结论高频超声对体表软组织肿块的诊断有重要临床价值。     

软组织超声频谱实验和分析

本文介绍了用窄带和宽带超声换能器对脂肪、肌肉、肌纤维瘤等软组织进行声衰减和散射的频谱实验和分析,并结合组织的生理结构进行了讨论。实验结果表明:(1)肌纤维组织的声衰减有明显的方向性,而肌纤维瘤则失去了这一特征,且声衰减增大。(2)频率在3MHz以下,背向散射很弱,超过3MHz后,散射的强度随频率的升高而近似成指数趋势上升。(3)接收换能器的带宽对声谱分布特征有很大影响。     

弯曲参数对软组织缝合过线器弯钩力学性能的影响

目的 探究弯钩偏转角和弯钩倾斜角对软组织缝合过线器弯钩力学性能的影响.方法 以远离针尖端端面(端面1)为研究对象,建立以力矩大小为因变量,弯钩偏转角和倾斜角为自变量的数学模型.探究偏转角和倾斜角为0°、10°、20°和30°时的力矩,并用数学模型求解出力矩.基于有限元分析法,使用SolidWorks软件建立偏转角和倾斜...     

巩膜的区域性力学性能研究

目的比较不同区域巩膜力学特性的差异。方法以健康家猪眼为材料,将巩膜分为前部、赤道部和后部3个区域,对整体眼球巩膜的不同区域分别进行局部压痕;沿赤道方向对不同区域巩膜进行环切,制成条带状试件,采用INSTRON 5544材料试验机进行单轴拉伸。结果正常生理载荷范围内,局部压痕法测得巩膜前部、赤道部、后部的刚度分别为(0.91±0.21)、(0.6±0.16)、(0.39±0.13)MPa;单轴拉伸测得巩膜前部、赤道部、后部的弹性模量分别为(1.28±0.37)、(0.95±0.31)、(0.72±0.28)MPa。结论局部压痕法能够反映巩膜的区域性力学特性;巩膜前部相比赤道区域及后部具有更强的刚度。实验结果为进一步探讨近视等眼部疾病的发病机理提供参考。     

具有双特征时间参数的生物软组织黏弹性性质的理论研究

目的 探索描述生物软组织黏弹性特性的普遍行为或规律。方法 根据生物软组织的力学结构,构建由两个线性弹簧和两个黏壶的不同组合构成的四元件黏弹性结构模型;并通过弹性理论,结合不同黏弹性模型的几何构型推导其运动微分方程,利用其微分方程分析不同四元件模型的应力松弛和蠕变行为以及反映弹性和黏性相结合的应力松弛时间和蠕变推迟时间。结果 所有可能的四元件黏弹性模型都具有普遍的本构关系、应力松弛和蠕变函数形式。通过比较模型预测结果与主动脉瓣、韧带和脑动脉等生物软组织的实验数据发现,四元件黏弹性模型能够很好地描述生物软组织的力学行为。“快”和“慢”两个特征时间τ₁和τ₂对生物软组织的应力松弛具有显著的影响。“快”松弛时间τ₁对应力达到稳定态所需时间有明显的影响,而“慢”松弛时间τ₂对松弛率的影响不显著,但对应力松弛的稳定态有明显的影响。结论 生物软组织的时间依赖性行为可以通过两个特征时间尺度来表征,即“快”和“慢”时间;且具有两个特征时间的生物软组织的应力-应变关系、应力松弛和蠕变函数具有相同的数学形式,这与所选择的...     

Noncontact Evaluation of Articular Cartilage Degeneration Using a Novel Ultrasound Water Jet Indentation System

We previously reported a noncontact ultrasound water jet indentation system for measuring and mapping tissue mechanical properties. The key idea was to utilize a water jet as an indenter as well as the coupling medium for high-frequency ultrasound. In this paper, the system was employed to assess articular cartilage degeneration, using stiffness ratio as an indicator of the mechanical properties of samples. Both the mechanical and acoustical properties of intact and degenerated bovine patellar articular cartilage (n = 8) were obtained in situ. It was found that the stiffness ratio was reduced by 44 ± 17% after the articular cartilage was treated by 0.25% trypsin at 37 °C for 4 h while no significant difference in thickness was observed between the intact and degenerated samples. A significant decrease of 36 ± 20% in the peak-to-peak amplitude of ultrasound echoes reflected from the cartilage surface was also found for the cartilage samples treated by trypsin. The results also showed that the stiffness obtained with the new method highly correlated with that measured using a standard mechanical testing protocol. A good reproducibility of the measurements was demonstrated. The present results showed that the ultrasound water jet indentation system may provide a potential tool for the non-destructive evaluation of articular cartilage degeneration by simultaneously obtaining mechanical properties, acoustical properties, and thickness data.     

利用一维 Fung 模型探讨长宽比对兔腹部皮肤单轴拉伸力学特性的影响

目的 从实验方法学角度研究不同的长宽比对皮肤条状试样单轴拉伸力学特性的影响。 方法 以新西兰大白兔腹部皮肤为研究对象,取其从头到脚(0°)和与之垂直(90°)的两个方向,获取长宽比从 2 ∶1~ 6 ∶1的多个条状试样,进行单轴拉伸测试至试样破坏。 经过实验数据处理,得到兔腹部皮肤单轴拉伸的 Kirchhoff 应力-Green 应变数据,利用一维 Fung 模型 S = cEexp(αE2)对其进行拟合,从而得到相应的材料参数 c、α,并对参数进行统计学分析。结果 两个方向上 c 值差异不明显(P= 0. 151),α 值差异比较大(P = 0. 001)。 两个方向上不同长宽比兔腹部试样参数 c、α 无显著性差异(P>0. 05)。 结论 在 2 ∶1~ 6 ∶1长宽比范围内,兔腹部皮肤试样不同长宽比对单轴拉伸力学特性无影响。     

Towards the Feasibility of Using Ultrasound to Determine Mechanical Properties of Tissues in a Bioreactor

Our ultimate goal is to non-destructively evaluate mechanical properties of tissue-engineered (TE) cartilage using ultrasound (US). We used agarose gels as surrogates for TE cartilage. Previously, we showed that mechanical properties measured using conventional methods were related to those measured using US, which suggested a way to non-destructively predict mechanical properties of samples with known volume fractions. In this study, we sought to determine whether the mechanical properties of samples, with unknown volume fractions could be predicted by US. Aggregate moduli were calculated for hydrogels as a function of SOS, based on concentration and density using a poroelastic model. The data were used to train a statistical model, which we then used to predict volume fractions and mechanical properties of unknown samples. Young’s and storage moduli were measured mechanically. The statistical model generally predicted the Young’s moduli in compression to within <10% of their mechanically measured value. We defined positive linear correlations between the aggregate modulus predicted from US and both the storage and Young’s moduli determined from mechanical tests. Mechanical properties of hydrogels with unknown volume fractions can be predicted successfully from US measurements. This method has the potential to predict mechanical properties of TE cartilage non-destructively in a bioreactor.     

离体组织导热率实验研究

目的生物组织热物性参数是揭示其热传输能力和载热能力及进一步研究生物传热机制的重要指标,导热率是生物组织热物性基本参数之一。方法本文基于等温加热法进行了猪瘦肉、猪脂肪、猪肝等离体组织导热率的实时在位测量和分析：首先选取三种生物组织样本各一块,在其中心位置放置热源,然后离中心不同距离设置五个温度观测点,并测量系统的功率时间变化曲线及各测量点的温度,最后经MATLAB处理获得各点的导热率数据。结果实验结果表明,上述三种组织具有不同的导热率,其中,猪瘦肉的导热率最大,猪肝的导热率次之,脂肪的导热率最小;同一组织内部的不同位置导热率相近。结论本文测量方法和结果对深入开展生物组织传热机制、组织无损温度重构和肿瘤热疗等研究具有重要意义。     

Quantification of Stiffness Change in Degenerated Articular Cartilage Using Optical Coherence Tomography-Based Air-Jet Indentation

Articular cartilage is a thin complex tissue that covers the bony ends of joints. Changes in the composition and structure of articular cartilage will cause degeneration, which may further lead to osteoarthritis. Decreased stiffness is one of the earliest symptoms of cartilage degeneration and also represents the imperfect quality of repaired cartilage. An optical coherence tomography (OCT)-based air-jet indentation system was recently developed in our group to measure the mechanical properties of soft tissues. In this study, this system was applied to quantify the change of mechanical properties of articular cartilage after degeneration induced by enzymatic digestions. Forty osteochondral disks (n = 20 × 2) were prepared from bovine patellae and treated with collagenase and trypsin digestions, respectively. The apparent stiffness of the cartilage was measured by the OCT-based air-jet indentation system before and after the degeneration. The results were also compared with those from a rigid contact mechanical indentation and an ultrasound water-jet indentation. Through the air-jet indentation, it was found that the articular cartilage stiffness dropped significantly by 84% (p < 0.001) and 63% (p < 0.001) on average after collagenase and trypsin digestions, respectively. The stiffness measured by the air-jet indentation system was highly correlated (R > 0.8, p < 0.001) with that from the other two indentation methods. This study demonstrated that the OCT-based air-jet indentation can be a useful tool to quantitatively assess the mechanical properties of articular cartilage, and this encourages us to further develop a miniaturized probe suitable for arthroscopic applications.     

基于光纤光栅的超声传感器实验研究

光纤光栅传感器具有许多独特优点,是近年来应用较多的一种传感器。本实验主要研究了FBG光栅传感器对超声波的响应情况。结果显示传感器输出信号强度与声功率表现了基本的线性,提示可以利用光纤光栅检测超声,此方法为体内超声场的无创测量提供了新的工具。