Studying animal mechanics is critical for understanding how signals in the neuromuscular system give rise to behavior and how force-sensing organs and sensory neurons work. Few techniques exist to provide forces and displacements appropriate for such studies. To address this technological gap, we developed a metrology using piezoresistive cantilevers as force–displacement sensors coupled to a feedback system to apply and maintain defined load profiles to micrometer-scale animals. We show that this system can deliver forces between 10−8 and 10−3 N across distances of up to 100 μm with a resolution of 12 nN between 0.1 Hz and 100 kHz. We use this new metrology to show that force–displacement curves of wild-type nematodes (Caenorhabditis elegans) are linear. Because nematodes have approximately cylindrical bodies, this finding demonstrates that nematode body mechanics can be modeled as a cylindrical shell under pressure. Little is known about the relative importance of hydrostatic pressure and shell mechanics, however. We show that dissipating pressure by cuticle puncture or decreasing it by hyperosmotic shock has only a modest effect on stiffness, whereas defects in the dpy-5 and lon-2 genes, which alter body shape and cuticle proteins, decrease and increase stiffness by 25% and 50%, respectively. This initial analysis of C. elegans body mechanics suggests that shell mechanics dominates stiffness and is a first step in understanding how body mechanics affect locomotion and force sensing.
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机译：研究动物力学对于理解神经肌肉系统中的信号如何引起行为以及力感测器官和感觉神经元如何工作至关重要。很少有技术可以提供适合这种研究的力和位移。为了解决这一技术差距，我们开发了一种使用压阻悬臂作为力-位移传感器的量测技术，该力-位移传感器与反馈系统耦合，以对微米级动物施加并维持定义的载荷曲线。我们表明，该系统可以在最大100μm的距离内传递10 −8 和10 −3 N之间的力，其分辨率为0.1 Hz至100 kHz之间的12 nN 。我们使用这种新的度量方法来显示野生型线虫（秀丽隐杆线虫）的力-位移曲线是线性的。由于线虫大约具有圆柱体，因此该发现表明，线虫体力学可以建模为在压力下的圆柱壳。然而，关于静水压力和壳体力学的相对重要性知之甚少。我们显示，通过角质层穿刺消散压力或通过高渗性休克降低压力仅对刚度有适度的影响，而改变身体形状和角质层蛋白质的dpy-5和lon-2基因的缺陷降低并增加了25％的刚度和50％。对秀丽隐杆线虫的人体力学的初步分析表明，壳体力学在刚度中占主导地位，是理解人体力学如何影响运动和力感测的第一步。
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