The authors would like to recognize the Center for Advanced Vehicular Systems (CAVS) and the Agricultural and Biological Engineering Department at Mississippi State University for supporting this work. This material is based upon work supported by the U.S. Army TACOM Life Cycle Command under Contract No. W56HZV-08-C-0236, through a subcontract with Mississippi State University, and was performed for the Simulation Based Reliability and Safety (SimBRS) research program. Also, this material is based upon work supported by the National Nuclear Security Administration, (Department of Energy) under award number [DE-FC26-06NT42755]. Finally, the authors would like to thank Mr. David Adams, Mr. Michael McCollum and Ms. Erin Colebeck for their effort in this research.

注：伦理学声明：目前的工作是唯一的机构的研究政策，严格遵循合规性（ORC）的指导方针合适的生物安全和Office。 1.生物材料样品采购<ol><li>穿戴个人防护装备按照实验室和/或机构的标准生物安全协议。穿封闭趾鞋，裤长，白大褂，手术手套，防护面罩和护目镜，同时处理猪组织和测试。 </li><li>获得健康猪的猪组织（头部，腹部，或后腿）从内1-2小时验尸当地的屠宰场。 </li><li>存放在生物安全袋猪组织，然后将它们放置在冰容器（〜5.56-7.22°C）。 注：使用温度计来检查，在猪样品的温度不低于7.22 C。 </li><li>运输猪组织到最近的实验室（在兽医学院在密西西比州立大学）进行清扫。 </li><li>在动物医学学院兽医的监督下，手术抽取猪的器官（脑，肝，肌肉，脂肪，或肌腱），并将它们放置在容器中充满磷酸盐缓冲液（PBS）的临时存储（pH值7.4）。 </li><li>存储的PBS容器在冰冷却器（〜5.56-7.22°C）和立即它们传送给试验机构进行样品制备和SHPB测试。 </li></ol> 2.生物材料样品制备<ol><li>从PBS容器中取出猪的器官并将其放置在无菌的表面。 </li><li>注：确定主纤维取向和位置对于每个测试样品。使用的圆筒模具以30毫米内径从猪的器官解剖测试样品。 </li><li>如果测试样品楔入圆筒模具内，注入的PBS通过夹层的相对端工具，以允许测试样品滑出完好无损。放置提取测试样品上的无菌表面的一个单独的区域。 </li><li>使用手术刀将样品剪裁成规定厚度和纵横比。 注：对于猪的样品SHPB试验，厚度为10-15毫米，而纵横比（厚度/直径）为0.33-0.50（ 图2）。 </li><li>使用卡尺测量在三个不同的位置的厚度和直径。 </li><li>存放在新鲜的PBS所有测试样本，直到SHPB设备准备进行测试。 注：确保样品屠宰后4小时内进行测试。 </li><li>丢弃样品不在圆柱形由于切口在横截面的错误或变化。发生在生物安全袋丢弃样本。重复步骤2.2-2.6，以获得额外的测试样品。 </li></ol> 3.拆分Hopkinson压杆测试<ol><li>将撞杆，入射杆，并在M传输酒吧等人的支柱SHPB测试。 注：确保杆可自由移动的触感和其接口彼此对准。提供一个止动件为发射杆以保证安全。 </li><li>连接附着于入射光和透射杆到信号放大器的应变计。打开信号调理放大器和数据采集模块计算机。 </li><li>初始化高速数据采集软件。 </li><li>验证信号的捕获活，看看他们是否在正常范围之内时，通过点击图标零抵消噪声信号。 </li><li>输入触发电平与所述数据速率（2兆赫）。 </li><li>初始化软件来记录一旦触发电平已经达到。 </li><li>加载相邻压力室撞杆。压力室填充到所希望的压力。 注：典型的压力范围为5-25磅。 </li><li>零出激光测速仪通过按下归零按钮并设置读取前锋巴- [R的速度通过​​设置反射条背后的激光传感器的前锋栏上。 </li><li>将样品封室，使得它不妨碍入射光和反射条的移动。将在与发射杆接触事件吧。 </li><li>出于校准的目的，运行测试（无样品）通过接通触发开关上的撞杆的压力室中。 </li><li>一旦数据被在所述计算机获得，保存和分析SHPB应变计数据（这将在下一节中讨论），以确保测试过程是否正常。 </li><li>将入射光和透射杆之间的柱状样品，然后关闭样品密封腔。 注：确保没有预处理的对样品进行。 </li><li>与样品置于入射光和透射杆之间执行任务3.4-3.7。 注：确保样品中心线的相同的条中心线。 proceedi前NG，还检查样品没有被压缩，但仍保留在相同的几何形状以前提取。 </li><li>测试完成后，使用一次性卫生湿巾从案发酒吧，酒吧传输和样品限制室取出样品碎片。处置所有碎片和抹布在生物安全袋。 </li><li>用70％的乙醇清洗液和卫生擦拭物消毒杆和样品封室。 </li></ol> 4. SHPB数据后处理<ol><li>打开“MSU高速率的软件19”为霍普金森杆波分析。 </li><li>通过检查设置窗口，选择“拉伸/压缩”的模式选项卡单轴检测选项开始软件。此外，选择“2计”中的规选项卡，然后单击“继续。” </li><li>在主窗口中，选择打开文件1选项卡，并从前前后后的应变计记录导航入射波数据NT吧。选择导入传输杆应变计记录打开文件2标签。 </li><li>选择参数选项卡，在主窗口并输入测试设置，包括物理参数：尺寸吧，电压应变因素的影响，应变片的位置，和粘弹性分散常数。点击“继续”。 </li><li>然后选择选择数据选项卡，在主窗口和使用光标条来减少数据集包含事件数据才之量，反射和透射波。点击“继续”。 </li><li>然后，选择在主窗口中选择波标签，并使用光标酒吧限制在入射波图，在反射波图的反射波，并在发射波图的透射波入射波。点击“继续”。 </li><li>在此之后，选择正确的选项卡，在主窗口，让软件来校正粘弹性分散20-21。 </li><li>没有写选择在主窗口的Shift键选项卡。在波图，由波选择选项卡单独选择每一个使用光标拖动事件，反射和透射波以相同的初始位置的时间。查看所有数据图中的波澜。完成后，单击“继续”。 </li><li>结果文件，单击保存负载，位移，位置和速度，型材“另存为”。 </li><li>使用在Microsoft Excel（或任何其他电子表格软件）的常规方法来计算使用霍普金森杆试验前测得的试样尺寸真应力和真应变。 </li></ol> 5. SHPB有限元建模<ol><li>使用商业有限元（FE）软件，创建SHPB建立的有限元模型。 注：使用相同的几何结构和材料特性。 </li><li>分配一个初始速度撞杆初始化有限元模拟的有限元模型。 注：速度在前锋条应该对应于在SHPB实验特定应变率9。 </li><li>创建SHPB建立的有限元模型，而不放在入射光和透射杆之间的一个示例。运行的有限元模拟。 注：模拟撞杆速度应了“无样本”条件下对应实验撞杆速度。分配在表1中对聚合物条的材料性质。 </li><li>验证是否应变测量（染色随时间变化）的实验和有限元模拟有较好的一致性。 </li><li>将生物材料样品放入SHPB建立的有限元模型。分配的三维实现（VUMAT文件格式22）在ISV材料模型的生物材料样品11的。 </li><li>执行使用三种不同的网目尺寸，然后对结果进行分析，以确定该解收敛一个网格细化研究。 注：网格大小对应于六面体和/或四面体单元的总数组成该有限元模型。选择有限元模型最低的网目尺寸后还模拟了9收敛。 </li><li>进行两步有限元模型校准。在第一步骤中，上载的实验数据转换成一维的ISV材料模型的实现。 </li><li>通过调整ISV材料模型的参数（ 见表1）校准实验模型的真应力-应变曲线的真应力-应变曲线。 注意：需要进一步的迭代，因为实验SHPB数据是三维的性质，而材料模型是一维的。 </li><li>分配ISV材料常数在SHPB建立的有限元模型的生物材料样品。 </li><li>运行FE仿真撞杆速度和样品变形应变速率对应的SHPB试验在相同的应变速率。 </li><li> COMPA从重新实验和有限元模拟良好的一致性（株随时间变化）的应变测量。 注：如果在有限元模拟和实验应变计值之间良好的一致性，则继续执行模型校准过程的第二步骤。如果没有，重复任务5.7-5.11。 </li><li>在有限元模型校准的第二步，运行有限元模拟应变数据SHPB实验后处理软件，MSU高速率的软件19-21。 注意：如果模拟真应力 - 应变响应比较实验真应力 - 应变响应，那么两步有限元模型校准已完成。如果没有，重复任务5.7-5.12。 </li><li>沿着有限元模型样品的中心线元素执行的体积平均装载方向（Σ33）的压力。 注意：如果该应力是在与一维的ISV材料模型结果的应力 - 应变曲线一致，然后将结果通过任务5.7得到-5.12完全校准。如果没有，重复任务5.7-5.13。通过一维实施ISV材料模型捕获的真应力 - 应变响应表示是在一个SHPB设置测试了生物材料的单轴真应力 - 应变响应。 </li></ol>

<ol>
	<li>Champion, H. R., Holcomb, J. B., Young, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Injuries+from+explosions:+physics,+biophysics,+pathology,+and+required+research+focus.">Injuries from explosions: physics, biophysics, pathology, and required research focus.</a> J Trauma. 66 (5), 1468-1477 (2009).</li><li>Aubry, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Summary+and+agreement+statement+of+the+First+International+Conference+on+Concussion+in+Sport,+Vienna+2001.+Recommendations+for+the+improvement+of+safety+and+health+of+athletes+who+may+suffer+concussive+injuries.">Summary and agreement statement of the First International Conference on Concussion in Sport, Vienna 2001. Recommendations for the improvement of safety and health of athletes who may suffer concussive injuries.</a> Br J Sports Med. 36 (1), 6-10 (2002).</li><li>Born, C. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blast+trauma:+the+fourth+weapon+of+mass+destruction.">Blast trauma: the fourth weapon of mass destruction.</a> Scand J Surg. 94 (4), 279-285 (2005).</li><li>Cullis, I. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blast+waves+and+how+they+interact+with+structures.">Blast waves and how they interact with structures.</a> J R Army Med Corps. 147, 16-26 (2001).</li><li>Ngo, T., Mendis, P., Gupta, A., Ramsay, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blast+Loading+and+Blast+Effects+on+Structures&#8211;An+Overview.">Blast Loading and Blast Effects on Structures&#8211;An Overview.</a> Electronic Journal of Structural Engineering. 7, 76-91 (2007).</li><li>Usmani, Z., Alghamdi, F., Kirk, D., Usmani, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intelligent+Agents+in+Extreme+Conditions+&#8211;+Modeling+and+Simulation+of+Suicide+Bombing+for+Risk+Assessment.">Intelligent Agents in Extreme Conditions &#8211; Modeling and Simulation of Suicide Bombing for Risk Assessment.</a> Web Intelligence and Intelligent Agents. , (2010).</li><li>Guskiewicz, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cumulative+effects+associated+with+recurrent+concussion+in+collegiate+football+players+the+NCAA+Concussion+Study.">Cumulative effects associated with recurrent concussion in collegiate football players the NCAA Concussion Study.</a> JAMA. 290 (19), 2549-2555 (2003).</li><li>Finkelstein, E., Corso, P., Miller, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Incidence and Economic Burden of Injuries in the United States. , (2006).</li><li>Prabhu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupled+experiment/finite+element+analysis+on+the+mechanical+response+of+porcine+brain+under+high+strain+rates.">Coupled experiment/finite element analysis on the mechanical response of porcine brain under high strain rates.</a> JMech Behav Biomed Mater. 4 (7), 1067-1080 (2011).</li><li>Horstemeyer, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Integrated Computational Materials Engineering (ICME): Using Multiscale Modeling to Invigorate Engineering Design with Science. , (2012).</li><li>Bouvard, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+general+inelastic+internal+state+variable+model+for+amorphous+glassy+polymers.">A general inelastic internal state variable model for amorphous glassy polymers.</a> Acta Mechanica. 213, 1-2 (2010).</li><li>Kenner, V. H., Goldsmith, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+on+a+simple+physical+model+of+the+head.">Impact on a simple physical model of the head.</a> J Biomech. 6 (1), 1-11 (1973).</li><li>Khalil, T. B., Viano, D. C., Smith, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+analysis+of+the+vibrational+characteristics+of+the+human+skull.">Experimental analysis of the vibrational characteristics of the human skull.</a> J. Sound Vib. 63 (3), 351-376 (1979).</li><li>Pervin, F., Chen, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+mechanical+response+of+bovine+gray+matter+and+white+matter+brain+tissues+under+compression.">Dynamic mechanical response of bovine gray matter and white matter brain tissues under compression.</a> J Biomech. 42 (6), 731-735 (2009).</li><li>Prevost, T. P., Balakrishnan, A., Suresh, S., Socrate, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechnics+of+brain+tissue.">Biomechnics of brain tissue.</a> Acta Biomater. 7 (1), 83-95 (2011).</li><li>Saraf, H., Ramesh, K. T., Lennon, A. M., Merkle, A. C., Roberts, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+properties+of+soft+human+tissues+under+dynamic+loading.J.">Mechanical properties of soft human tissues under dynamic loading.J.</a> J Biomech. 40 (9), 1960-1967 (2007).</li><li>Van Sligtenhorst, C., Cronin, D. S., Wayne Brodland, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+strain+rate+compressive+properties+of+bovine+muscle+tissue+determined+using+a+split+Hopkinson+bar+apparatus.">High strain rate compressive properties of bovine muscle tissue determined using a split Hopkinson bar apparatus.</a> J Biomech. 39 (10), 1852-1858 (2006).</li><li>Song, B., Chen, W., Ge, Y., Weerasooriya, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+and+quasi-static+compressive+response+of+porcine+muscle.">Dynamic and quasi-static compressive response of porcine muscle.</a> J Biomech. 40 (13), 2999-3005 (2007).</li><li>. MSU JHBT Data Processing and MSU High Rate Software Manual Available from: <a target="_blank" href="https://icme.hpc.msstate.edu/mediawiki/index.php/File:MSU_JHBT_Data_Processing_and_MSU_High_Rate_Software_Manual.zip">https://icme.hpc.msstate.edu/mediawiki/index.php/File:MSU_JHBT_Data_Processing_and_MSU_High_Rate_Software_Manual.zip</a> (2014)</li><li>Zhao, H., Gary, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+use+of+SHPB+techniques+to+determine+the+dynamic+behavior+of+materials+in+the+range+of+small+strains.">On the use of SHPB techniques to determine the dynamic behavior of materials in the range of small strains.</a> Int J Solids Struct. 33 (23), 3363-3375 (1996).</li><li>Zhao, H., Gary, G., Klepaczko, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+use+of+a+viscoelastic+split+hopkinson+pressure+bar.">On the use of a viscoelastic split hopkinson pressure bar.</a> Int J Impact Eng. 19 (4), 319-330 (1997).</li><li>. MSU TP Ver 1.1. Available from: <a target="_blank" href="https://icme.hpc.msstate.edu/mediawiki/index.php/File:MSU_TP_Ver_1.1.zip">https://icme.hpc.msstate.edu/mediawiki/index.php/File:MSU_TP_Ver_1.1.zip</a> (2014)</li><li>Gray, G. T., Blumenthal, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ASM Handbook, Mechanical Testing and Evaluation. 8, 488-496 (2000).</li><li>Dharan, C. K. H., Hauser, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+stress-strain+characteristics+at+very+high+strain+rates.">Determination of stress-strain characteristics at very high strain rates.</a> Exp. Mech. 10 (9), 370-376 (1970).</li><li>Chen, J., Priddy, L. B., Prabhu, R., Marin, E. B., Horstemeyer, M. F., Williams, L. N., Liao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+Injury:+Mechanical+Response+of+Porcine+Liver+Tissue+under+High+Strain+Rate+Compression+Testing.">Traumatic Injury: Mechanical Response of Porcine Liver Tissue under High Strain Rate Compression Testing.</a> Proceedings of the ASME 2009 Summer Bioengineering Conference (SBC2009). , (2009).</li></ol>

作者声明：保证有与此相关的出版物中的所有材料没有利益冲突。

所报告的方法，它耦合SHPB实验和SHPB的有限元建模提供了一种新的和独特的技术来评估生物材料在高应变率单轴真应力 - 应变响应。为了促使机械性质固有的天然组织，必须小心SHPB测试之前保持之间5.56-7.22℃下的生物材料样品。如果试样被冷却到低于5.56℃，存在于组织中水开始crystalize入冰水，随后改变了组织的机械性能。虽然其他研究人员15-18冻结样品从机械降解保鲜的目的，结果从SHPB...

动机 耦合分离的基本目标-霍普金森压杆（SHPB）实验/软生物材料（如脑，肝，肌腱，脂肪等 ），有限元建模是提取其单轴机械行为对人体FE进一步实施有害的机械载荷下的模拟。人体的有限元（FE）的模型包括一个详细人体模型和历史依赖性多尺度粘弹性粘塑性内部状态变量（ISV）材料对各种人体器官模型。这种人体模型可以用于框架搭建伤害保障更好的标准，以设计新颖护具，并且使乘员为中心的车辆设计。 两种模式率高伤害已被广泛观测到人类的创伤：爆炸冲击波和钝物撞击。爆炸性武器爆炸伤害traumati的主要来源Ç损伤（TI）和死亡的战场上1的首要原因。当引爆，炸药这些形成产生大的和突然的加速和变形向外传播的冲击波。由此产生的载荷会对那些暴露的严重威胁。虽然任何部分的解剖结构可通过冲击波受伤，关注的主要区域是：（1）下肢由于其靠近地面，和（2）的头部自伤能抑制正常的脑功能和存活2 3。这些损伤可以分为取决于损伤的持续的类型的伯，仲，或叔受伤。因为爆炸的强度的特征在于它的重量或尺寸，间隔距离，正脉冲的持续时间，并通过它传播介质，它可以是难以充分归类这些伤害3-6。国会报告指出，军事人员因遭遇爆炸近179,000外伤武器装备和车辆碰撞在伊拉克和阿富汗从2000年至2010年3月2日，由于自然和现代作战位置，头部受伤是军事和平民3领先的担忧。 除了作战场景，TI有多种原因，包括汽车的创伤;圈地，摩托车和家庭事故;和运动损伤。例如，尽管改进安全设备和协议，机械引起创伤性脑损伤（TBI）仍然是死亡率和发病率终身在美国疾病控制中心和预防中心（CDC）的主要来源报道大约140万TBI每个事件年，其中近5万是致命的。美式足球就占了30多万科技企业孵化器，每年7。这种伤害的幸存者是在危险中对有关的感觉，认知和交流的长期神经系统并发症。这时，大约有530万美国人患有这些慢性病的缺点和残疾。直接和间接美国的医疗费用2000年至2010年总额为60十亿8。然而，这些数字没有考虑非医疗费用和损失，或者那些招致家人和朋友支持TBI患者。超越纯粹的经济分析，TBI诱导的残疾创建一个显著降低生活质量，可以表现为在家庭和社会一个显著负担。 需要进一步理解的形成，表征和预防的TI的是明确的。导致TI提供的洞察力和机会，以减少暴露或改善安全功能为那些在为TI潜在风险的基本机制的生物力学研究。此外，TI的形成一般的理解更加进步可以提高诊断的方法和标准，提供医疗专业人士谁TI治疗与改善预后更好的手段S和拯救生命。 都需要更好地了解损伤机制和更好地了解受伤发展生物力学的发展对人体有效的保护措施。从历史上看，模拟旨在预测伤病已经阻碍了采用计算的限制，以及解剖的保真度和材料模型。全身模拟已经集中在对每个正文部分的整体负载，但局部应力，应变和损伤的各器官，肌肉，骨骼等尚未观察。例如，肩时刻型号使用臂，负荷，以及所施加的角的尺寸，以搜索指定一个特定的场景是否是危险的表格值。的计算，自然是为快速估计有帮助，但不能捕捉到什么地方从手一路发生在肩部，尤其是在损害和伤害本质上是本地的。其次，FE simulations已被用来捕捉本地响应。在这些努力的限制一直没有FEA本身，而是定义爆炸伤荷载作用下身体的每个部位的行为的材料模型。以前使用的材料模型改编自简单的材料，并没有努力捕捉生物组织表现出复杂的机械行为的无数。因此，高保真计算模型与人体器官ISV材料模型代表了最现实的方式来调查TI的物理学和生物力学，设计创新的防护装备，并建立损伤指标更好的标准。 背景拆分霍普金森压杆（SHPB）和内部状态变量（ISV）材料模型 由于涉及体内试验人体器官和大规模人类尸体测试相关的后勤问题，在CURR伦理问题耳鼻喉科的研究工作包括使用从机关从动物中提取的代理人准备标本力学实验在体外 （ 例如 ，猪作为最常用的替代）。聚合物SHPB一直是体外测试软生物材料在高应变率的首选方法。从SHPB从组织的显微结构特征的测试和相应的组织损伤有关的信息的相关变形行为纳入我们的ISV材料模型器官机械描述9-10。这些材料模型，然后落实到我们的虚拟人体模型来进行各种伤病的有限元分析。这个过程使我们能够走向的准确预测的损伤的物 ​​理和性质为不同的机械载荷的条件下一个给定的器官（ 例如，鼓风诱导，车祸和钝的影响），而不需要进一步的物理实验的目标。为了准确地描述牛逼他现象的机械性能，特别是更高水平的应变速率依赖性，在人体内的FE模拟中使用的生物材料，SHPB实验上的生物材料以获得在有关人力TI的应变率动态力学响应。在SHPB设置在密西西比州立大学（MSU）的中心高级车辆系统（CAVS），概述是在图1。 以前的研究已经表明，SHPB试验具有与之相关联的12-18三大缺陷。在第一和最显著一个是材料惯性效果，其示出了在生物材料样品的作为初始尖峰的高应变速率机械响应。为了克服这个问题，以前的研究工作表明从圆柱形修改试样的几何形状在形状上立方形或环形形状。从这些研究得到的力学行为是不同的回回米彼此因为试样的几何形状影响波的传播，波的相互作用，以及机械响应。这种类型的修饰的试样的几何形状导致了生物材料的机械响应（多轴和非均匀应力状态）的错误表示。第二个主要的缺陷是无法在测试过程中保持动力的平衡。研究人员通过减少样品厚度与直径的比率和/或冷冻的组织在测试之前克服了这个问题。同时减少了样品的厚度与直径的比率寻址动态力平衡的问题，冻结的组织进一步复杂的测试过程，因为它改变了材料的性能由于存在于组织中的水的结晶。多项研究完全放弃了SHPB以避免上述缺陷，并用于冲击管，以获得在各种动物模型（大鼠，猪等 ）的压力-时间响应。但是，这些一IMAL机型不给予必要在有限元模拟中使用的材料模型一维单向应力 - 应变行为。第三缺陷是SHPB的失败，得到，因为滚筒抛光试样的一维应力 - 应变的结果，由于该材料的柔软性和在试样含水量的量。 因此，SHPB提出了一个可行的测试设备，以争取高应变率数据。为软质材料，但是，SHPB诱导产生三维应力状态主要由静水压力膨出，但一维的应力 - 应变数据是需要的。我们在这里展示一个人如何仍然可以使用SHPB争取为材料模型校准的一维单向真实应力 - 应变曲线;然而，涉及在获得单轴真应力 - 应变曲线的过程是复杂的。此过程既包括多轴实验数据和有限元模拟的结果，它需要的迭代校准材料模型常数。该一维实现在MATLAB中的ISV材料模型，也称为料点模拟器中，需要一维实验数据的校准。因此，ISV材料模型是使用系统校准过程优化。在这里，从SHPB测试实验数据被认为是在波浪理论的制定和动力平衡（MSU高速率的软件）的范围内。以占聚合物SHPB，粘弹性色散方程的粘弹分散，据报道由Zhao 等人 （2007），在MSU高速率软件实施的。粘弹性色散方程有助于确保动力的平衡，同时测试。所述一维物质点模拟器然后在一对夫妇实验-FE建模方法的上下文调整，直到这两个过程被认为是适当的兼容的，即，来自两个数据吻合较好。这些数据是用于通过比较在MATLAB材料响应仿真的（一维）的机械响应和SHPB有限元模型的（一维）试样中心线应力调整ISV模型材料常数。在这里，有限元模型的样本应力分量是沿着波浪荷载方向。然后有限元模型试样的三维行为校准通过反复进行有限元模拟和调整的ISV常量，使得体积平均装载方向应力与实验真应力 - 应变响应很好的相关性。因此，实验数据，有限元分析结果，和一维的ISV材料模型之间迭代优化过程进行的。 表1给出的ISV材料模型（MSU TP 1.1版）11的变量的汇总。 最重要的元素，以这种方法是获得生物材料的一维机械响应和其材料参数对于ISV材料模型，规避该应力状态的非均匀性的SHPB测试问题。它也分离出从惯性效应所产生的生物材料的初始非线性响应并呈现一个机械响应是固有的材料。耦合方法也表明，在试样的几何形状的变化完全改变了边值问题（BVP）和装载方向真应力 - 应变试样。这样，上述方法可用于任何材料模型（现象或显微为主），用于校准，然后损害机械载荷下模拟人体器官的高应变速率的行为。

<table border="0" cellpadding="0" cellspacing="0" width="951">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:699px;">Description</td>
			<td style="width:141px;">Provider</td>
			<td style="width:53px;"></td>
			<td style="width:59px;">Quantity</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">High pressure 316 stainless steel threaded pipe fitting, 1/2 male x 1/4 female pipe size, hex reducing bushing</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Type 316 stainless steel threaded pipe fitting, 3/4 male x 1/4 female, hex reducing bushing 150 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Easy-maintenance type 316SS ball valve, with 316 stainless steel ends, 1/2&#34; NPT female</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Easy-maintenance type 316SS ball valve, with 316 stainless steel ends, 3/4&#34; NPT female</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ASME-code stainless steel pop-safety valve, 1/4 NPT male, 300 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Precision extreme-pressure 316SS pipe fitting, 1/2 x 1/2 pipe size, 1-7/8&#34; length, hex nipple</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">8</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">type 316 stainless steel threaded pipe fitting, 1/2 pipe size, tee, 150 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Test gauge with safety case, polyester case, standard, dry, 600 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Digital gauge, plastic case, 2-1/2&#34; dial, 1/4 bottom connection, 300 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Type 316 stainless steel 37 degree flared tube fitting, adapter for 1/4&#34; tube OD x 1/8&#34; NPT male pipe</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">12</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">303 stainless steel 37 degree JIC swivel fitting for 3/16&#34; ID</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">12</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">High-pressure chemical hose, 3/16&#34; ID, 0.312&#34; OD, 3000 psi</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">6</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">High-Purity Gas Regulator Single-Stage, Nitrogen, 0-125 PSI, CGA #580</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hose for Nitrogen Gas, Argon, and Oxygen Brass Fem Fittings, PTFE Hose, 3&#39;L, 1/4&#34; ID, 3600 PSI</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Extreme-Pressure 316 SS Threaded Pipe Fitting 1/4 X 1/4 Pipe Size, Hex Nipple</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">4</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Extreme-Pressure 316 SS Threaded Pipe Fitting 3/4 X 3/4 Pipe Size, Hex Nipple</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Extreme-Pressure 316 SS Threaded Pipe Fitting 1/4 Male X 1/8 Female Pipe Size, Hex Bushing</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Standard Brass Compression Tube Fitting Adapter for 1/4&#34; Tube OD X 1/4&#34; NPTF Male Pipe</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">4</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Kobalt 1/4 in Mini Regulator with Gauge</td>
			<td>Lowes</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1/4&#34; x 25 ft polyethylene tubing</td>
			<td>Lowes</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1-1/2&#34; Diameter Polycarbonate (PC) Rod</td>
			<td>McMaster-Carr</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">LTV-35 4-Way Valve Mead Fluid Dynamics</td>
			<td>Motion Industries</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Pneumatic double action actuator</td>
			<td>Valtronic</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Stainless Steel Ball Valve 1/2&#34;</td>
			<td>Valtronic</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Buckeye pressure vessel</td>
			<td>Buckeye</td>
			<td></td>
			<td align="right">2</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;">SR-4 General Purpose FAE-25-35SX Strain Gages</td>
			<td style="width:141px;">Micro-Measurement Vishay Precision Group</td>
			<td style="width:53px;"></td>
			<td align="right">2</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;">M-M Signal Conditioning Amplifier 2310A</td>
			<td style="width:141px;">Micro-Measurement Vishay Precision Group</td>
			<td style="width:53px;"></td>
			<td align="right">1</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laser ROLS-W optical sensor</td>
			<td>Monarch Instruments</td>
			<td></td>
			<td align="right">1</td>
		</tr>
	</tbody>
</table>

a coupled experiment-finite element modeling methodology for assessing high strain rate mechanical response of soft biomaterials

这项研究提供了一个联合实验和有限元（FE）模拟方法用于检查时暴露在高应变率软生物材料（ 如脑，肝，肌腱，脂肪等 ）的力学性能。本研究采用分离式霍普金森压杆（SHPB）生成的100-1,500秒的应变率-1。该SHPB采用的撞杆组成的粘弹性材料（聚碳酸酯）的。获得生物材料样品死后不久和SHPB测试做好准备。将试样的入射光和透射杆之间，并且SHPB的气动元件被激活，以驱动锤杆朝向入射杆。由此产生的碰撞所产生的压缩应力波（ 即入射波），通过这一事件吧旅行。当压缩应力波到达入射杆的末端，一个部分继续向前通过样品和传送杆（一.E。透射波），而另一部分通过事件杆作为拉伸波反转（ 即反射波）。这些波是用安装在入射光和透射杆应变计测量。样品的真应力 - 应变行为是从根据波传播和动态力平衡方程来确定。该实验的应力 - 应变响应是三维的性质，因为在试样鼓出。这样，静水压力（第一不变量）被用来产生的应力 - 应变响应。以提取的单轴（一维）的机械组织的响应，使用实验结果和有限元分析（FEA），​​它包含了一个用于组织内部状态变量（ISV）材料模型进行迭代耦合优化。在实验装置的有限元模拟中使用的材料，ISV模型反复校准（ 即优化）的实验数据，塔T中的实验和有限元分析应变值和应力第一不变量是很好的一致性。

<html>耦合方法的有效性是例示在图3中，在这里对大脑的SHPB试验应力-应变响应是在一个较低的应力状态（0.32兆帕的峰值应力）相比于一维材料的应力状态点模拟器（具有0.74的峰值兆帕），这是类似于对FE样品中心线（元件）的平均值。这是由于变形软生物材料表现出的性质。因为应变率很高，并且该生物材料的波的速度和强度低，在材料需求的非均匀变形的惯性和应力波的传播。这?...

Watch this Scientific Journal Video about A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials at JoVE.com

A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials

目前的研究规定了耦合实验-有限元模拟方法获得的软生物材料（脑，肝，肌腱，脂肪等 ）的单轴动态力学响应。那出现的多轴实验的结果，因为样品的从斯普利特 - 霍普金森压杆测试鼓胀获得通过时，生物材料的有限元分析的迭代优化模拟被渲染到单轴真应力 - 应变行为。

一个耦合试验，有限元建模方法以评估生物材料软的高应变率力学响应

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. ...

a-coupled-experiment-finite-element-modeling-methodology-for

Research

JoVE Journal

Bioengineering

12.4K 次观看.  Mississippi State University. 目前的研究规定了耦合实验-有限元模拟方法获得的软生物材料（脑，肝，肌腱，脂肪等 ）的单轴动态力学响应。那出现的多轴实验的结果，因为样品的从斯普利特 - 霍普金森压杆测试鼓胀获得通过时，生物材料的有限元分析的迭代优化模拟被渲染到单轴真应力 - 应变行为。 

视频: A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials

Microfabricated Platforms for Mechanically Dynamic Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

微机械动态细胞培养平台

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or ...

科研

生物工程

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.

聚合物芯片高通量发现的生物材料

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a ...

An Improved Mechanical Testing Method to Assess Bone-implant Anchorage

Recent advances in material science have led to a substantial increase in the topographical complexity of implant surfaces, both on a micro- and a nano-scale. As such, traditional methods of describing implant surfaces -&#160;namely numerical determinants of surface roughness -&#160;are inadequate for predicting in vivo performance. Biomechanical testing provides an accurate and comparative platform to analyze the performance of biomaterial surfaces. An improved mechanical testing method to test the anchorage of bone to candidate implant surfaces is presented. The method is applicable to both early and later stages of healing and can be employed for any range of chemically or mechanically modified surfaces -&#160;but not smooth surfaces. Custom rectangular implants are placed bilaterally in the distal femora of male Wistar rats and collected with the surrounding bone. Test specimens are prepared and potted using a novel breakaway mold and the disruption test is conducted using a mechanical testing machine. This method allows for alignment of the disruption force exactly perpendicular, or parallel, to the plane of the implant surface, and provides an accurate and reproducible means for isolating an exact peri-implant region for testing.

An improved method to mechanically test bone anchorage to candidate implant surfaces is presented. This method allows for alignment of the disruption force exactly perpendicular, or parallel, to the plane of the implant surface, and provides an accurate means to direct the disruption forces to an exact peri-implant region.

一种改进的机械性能测试方法来评估骨种植体支抗

Recent advances in material science have led to a substantial increase in the topographical complexity of implant surfaces, both on a micro- and a ...

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an area of productive research with over 1,400 published animal studies in just the last 5 years. Numerous techniques have been developed for quantifying smooth muscle activity of the stomach, small intestine, and colon. In vitro and ex vivo techniques offer powerful tools for mechanistic studies of GI function, but outside the context of the integrated systems inherent to an intact organism. Typically, measuring in vivo smooth muscle contractions of the stomach has involved an anesthetized preparation coupled with the introduction of a surgically placed pressure sensor, a static pressure load such as a mildly inflated balloon or by distending the stomach with fluid under barostatically-controlled feedback. Yet many of these approaches present unique disadvantages regarding both the interpretation of results as well as applicability for in vivo use in conscious experimental animal models. The use of dual element strain gages that have been affixed to the serosal surface of the GI tract has offered numerous experimental advantages, which may continue to outweigh the disadvantages. Since these gages are not commercially available, this video presentation provides a detailed, step-by-step guide to the fabrication of the current design of these gages. The strain gage described in this protocol is a design for recording gastric motility in rats. This design has been modified for recording smooth muscle activity along the entire GI tract and requires only subtle variation in the overall fabrication. Representative data from the entire GI tract are included as well as discussion of analysis methods, data interpretation and presentation.

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

The in vivo measurement of smooth muscle contractions along the gastrointestinal tract of laboratory animals remains a powerful, though underutilized, technique. Flexible, dual element strain gages are not commercially available and require fabrication. This protocol describes the construction of reliable, inexpensive strain gages for acute or chronic implantation in rodents.

的微型双元应变计测量加工和植入<em&gt;体内</em&gt;胃肠收缩鼠害。

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an ...

An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular cartilage impairs its load-bearing function substantially as it experiences tremendous chemical degradation, i.e. proteoglycan loss and collagen fibril disruption. One promising way to investigate chemical damage mechanisms during OA is to expose the cartilage specimens to an external solute and monitor the diffusion of the molecules. The degree of cartilage damage (i.e. concentration and configuration of essential macromolecules) is associated with collisional energy loss of external solutes while moving across articular cartilage creates different diffusion characteristics compared to healthy cartilage. In this study, we introduce a protocol, which consists of several steps and is based on previously developed experimental micro-Computed Tomography (micro-CT) and finite element modeling. The transport of charged and uncharged iodinated molecules is first recorded using micro-CT, which is followed by applying biphasic-solute and multiphasic finite element models to obtain diffusion coefficients and fixed charge densities across cartilage zones.

We propose a protocol to investigate the transport of charged and uncharged molecules across articular cartilage with the aid of recently developed experimental and numerical methods.

实验和有限元议定书调查中性和带电溶质的跨关节软骨运输

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular ...

Magnetic Levitation Coupled with Portable Imaging and Analysis for Disease Diagnostics

Currently, many clinical diagnostic procedures are complex, costly, inefficient, and inaccessible to a large population in the world. The requirements for specialized equipment and trained personnel require that many diagnostic tests be performed at remote, centralized clinical laboratories. Magnetic levitation is a simple yet powerful technique and can be applied to levitate cells, which are suspended in a paramagnetic solution and placed in a magnetic field, at a position determined by equilibrium between a magnetic force and a buoyancy force. Here, we present a versatile platform technology designed for point-of-care diagnostics which uses magnetic levitation coupled to microscopic imaging and automated analysis to determine the density distribution of a patient's cells as a useful diagnostic indicator. We present two platforms operating on this principle: (i) a smartphone-compatible version of the technology, where the built-in smartphone camera is used to image cells in the magnetic field and a smartphone application processes the images and to measures the density distribution of the cells and (ii) a self-contained version where a camera board is used to capture images and an embedded processing unit with attached thin-film-transistor (TFT) screen measures and displays the results. Demonstrated applications include: (i) measuring the altered distribution of a cell population with a disease phenotype compared to a healthy phenotype, which is applied to sickle cell disease diagnosis, and (ii) separation of different cell types based on their characteristic densities, which is applied to separate white blood cells from red blood cells for white blood cell cytometry. These applications, as well as future extensions of the essential density-based measurements enabled by this portable, user-friendly platform technology, will significantly enhance disease diagnostic capabilities at the point of care.

We present a magnetic levitation technique coupled with automated imaging and analysis in both a smartphone-compatible device and a device with embedded imaging and processing. This is applied to measure the density distribution of cells with two demonstrated biomedical applications: sickle cell disease diagnosis and separating white and red blood cells.

磁悬浮加上便携式成像与分析诊断疾病

Currently, many clinical diagnostic procedures are complex, costly, inefficient, and inaccessible to a large population in the world. The requirements for ...

Quantification of Strain in a Porcine Model of Skin Expansion Using Multi-View Stereo and Isogeometric Kinematics

Tissue expansion is a popular technique in plastic and reconstructive surgery that grows skin in vivo for correction of large defects such as burns and giant congenital nevi. Despite its widespread use, planning and executing an expansion protocol is challenging due to the difficulty in measuring the deformation imposed at each inflation step and over the length of the procedure. Quantifying the deformation fields is crucial, as the distribution of stretch over time determines the rate and amount of skin grown at the end of the treatment. In this manuscript, we present a method to study tissue expansion in order to gain quantitative knowledge of the deformations induced during an expansion process. This experimental protocol incorporates multi-view stereo and isogeometric kinematic analysis in a porcine model of tissue expansion. Multi-view stereo allows three-dimensional geometric reconstruction from uncalibrated sequences of images. The isogeometric kinematic analysis uses splines to describe the regional deformations between smooth surfaces with few mesh points. Our protocol has the potential to bridge the gap between basic scientific inquiry regarding the mechanics of skin expansion and the clinical setting. Eventually, we expect that the knowledge gained with our methodology will enable treatment planning using computational simulations of skin deformation in a personalized manner.

This protocol uses multi-view stereo to generate three-dimensional (3D) models out of uncalibrated sequences of photographs, making it affordable and adjustable to a surgical setting. Strain maps between the 3D models are quantified with spline-based isogeometric kinematics, which facilitate representation of smooth surfaces over coarse meshes sharing the same parameterization.

在皮肤扩张使用多视点立体和Isogeometric运动学的猪模型应变的定量

Tissue expansion is a popular technique in plastic and reconstructive surgery that grows skin in vivo for correction of large defects such as burns and ...

Methodology for Biomimetic Chemical Neuromodulation of Rat Retinas with the Neurotransmitter Glutamate In Vitro

Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are an emerging treatment for photoreceptor degenerative diseases that seek to restore vision by artificially stimulating the surviving retinal neurons in the hope of eliciting comprehensible visual perception in patients. Current retinal prostheses have demonstrated success in restoring limited vision to patients using an array of electrodes to electrically stimulate the retina but face substantial physical barriers in restoring high acuity, natural vision to patients. Chemical neurostimulation using native neurotransmitters is a biomimetic alternative to electrical stimulation and could bypass the fundamental limitations associated with retinal prostheses using electrical neurostimulation. Specifically, chemical neurostimulation has the potential to restore more natural vision with comparable or better visual acuities to patients by injecting very small quantities of neurotransmitters, the same natural agents of communication used by retinal chemical synapses, at much finer resolution than current electrical prostheses. However, as a relatively unexplored stimulation paradigm, there is no established protocol for achieving chemical stimulation of the retina in vitro. The purpose of this work is to provide a detailed framework for accomplishing chemical stimulation of the retina for investigators who wish to study the potential of chemical neuromodulation of the retina or similar neural tissues in vitro. In this work, we describe the experimental setup and methodology for eliciting retinal ganglion cell (RGC) spike responses similar to visual light responses in wild-type and photoreceptor-degenerated wholemount rat retinas by injecting controlled volumes of the neurotransmitter glutamate into the subretinal space using glass micropipettes and a custom multiport microfluidic device. This methodology and protocol are general enough to be adapted for neuromodulation using other neurotransmitters or even other neural tissues.

Methodology for Biomimetic Chemical Neuromodulation of Rat Retinas with the Neurotransmitter Glutamate In Vitro

This protocol describes a novel method for investigating a form of chemical neurostimulation of wholemount rat retinas in vitro with the neurotransmitter glutamate. Chemical neurostimulation is a promising alternative to the conventional electrical neurostimulation of retinal neurons for treating irreversible blindness caused by photoreceptor degenerative diseases.

大鼠视网膜仿生化学调节的神经递质谷氨酸的体外实验方法

Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are ...

Stiffness Measurement of Soft Silicone Substrates for Mechanobiology Studies Using a Widefield Fluorescence Microscope

Soft tissues in the human body typically have stiffness in the kilopascal (kPa) range. Accordingly, silicone and hydrogel flexible substrates have been proven to be useful substrates for culturing cells in a physical microenvironment that partially mimics in vivo conditions. Here, we present a simple protocol for characterizing the Young's moduli of isotropic linear elastic substrates typically used for mechanobiology studies. The protocol consists of preparing a soft silicone substrate on a Petri dish or stiff silicone, coating the top surface of the silicone substrate with fluorescent beads, using a millimeter-scale sphere to indent the top surface (by gravity), imaging the fluorescent beads on the indented silicone surface using a fluorescence microscope, and analyzing the resultant images to calculate the Young's modulus of the silicone substrate. Coupling the substrate's top surface with a moduli extracellular matrix protein (in addition to the fluorescent beads) allows the silicone substrate to be readily used for cell plating and subsequent studies using traction force microscopy experiments. The use of stiff silicone, instead of a Petri dish, as the base of the soft silicone, enables the use of mechanobiology studies involving external stretch. A specific advantage of this protocol is that a widefield fluorescence microscope, which is commonly available in many labs, is the major equipment necessary for this procedure. We demonstrate this protocol by measuring the Young's modulus of soft silicone substrates of different elastic moduli.

Substrates with stiffness in the kilopascal-range are useful to study the response of cells to physiologically relevant micro-environment stiffness. Using just a widefield fluorescence microscope, the Young's modulus of soft silicone gels can be determined using an indentation with a suitable sphere.

用 Widefield 荧光显微镜研究软硅基美国匹茨堡的刚度测量

Soft tissues in the human body typically have stiffness in the kilopascal (kPa) range. Accordingly, silicone and hydrogel flexible substrates have been ...

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive models, which provide a mathematical representation of the mechanical function of those structures. This presented biaxial mechanical testing protocol involves (i) tissue acquisition, (ii) the preparation of tissue specimens, (iii) biaxial mechanical testing, and (iv) postprocessing of the acquired data. First, tissue acquisition requires obtaining porcine or ovine hearts from a local Food and Drug Administration-approved abattoir for later dissection to retrieve the valve leaflets. Second, tissue preparation requires using tissue specimen cutters on the leaflet tissue to extract a clear zone for testing. Third, biaxial mechanical testing of the leaflet specimen requires the use of a commercial biaxial mechanical tester, which consists of force-controlled, displacement-controlled, and stress-relaxation testing protocols to characterize the leaflet tissue&#39;s mechanical properties. Finally, post-processing requires the use of data image correlation techniques and force and displacement readings to summarize the tissue&#39;s mechanical behaviors in response to external loading. In general, results from biaxial testing demonstrate that the leaflet tissues yield a nonlinear, anisotropic mechanical response. The presented biaxial testing procedure is advantageous to other methods since the method presented here allows for a more comprehensive characterization of the valve leaflet tissue under one unified testing scheme, as opposed to separate testing protocols on different tissue specimens. The proposed testing method has its limitations in that shear stress is potentially present in the tissue sample. However, any potential shear is presumed negligible.

This protocol involves characterizations of atrioventricular valve leaflets with force-controlled, displacement-controlled, and stress-relaxation biaxial mechanical testing procedures. Results acquired with this protocol can be used for constitutive model development to simulate the mechanical behavior of functioning valves under a finite element simulation framework.

房室心脏瓣膜的双轴力学特性

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive ...