Cincinnati Children's Hospital Medical Center, Orthopaedics MLC 2017, Cincinnati, OH 45229-3039, USA.
J Biomech. 2010 Aug 10;43(11):2244-8. doi: 10.1016/j.jbiomech.2010.04.006. Epub 2010 May 6.
Physiological stresses are fundamental to biomechanical testing, mechanobiological analyses, implant design, and tissue engineering. The purpose of this study was to design, fabricate, and evaluate compressive stress sensors packaged for extended, in vivo implantation in the annulus of the intervertebral disc. A commercial microelectromechanical systems (MEMS) pressure sensor die was selected as the active element for a custom stress sensor. The sensor die was modified and packaged to protect the electrical system from the biochemical and biomechanical environment. Completed sensors were calibrated under hydrostatic pressure and solid contact compression. Calibrations were performed before and after 8 weeks of in vivo implantation in a porcine disc. For the two reported sensors, stress and voltage were linearly correlated over a range of 0-1.8 MPa with less than 5% change in sensitivity. Sensitivity to solid contact stress was within 10% of that from hydrostatic pressure. In contrast to most previous studies, in which disc pressure was measured in the fluidic nucleus pulposus, these sensors may be used to measure in vivo dynamic compressive stresses in the annulus at magnitudes typical of the musculoskeletal system in a large animal over a relatively long post-operative time.
生理应激是生物力学测试、机械生物学分析、植入物设计和组织工程的基础。本研究旨在设计、制造和评估用于椎间盘环内长期体内植入的压缩应力传感器。选择商用微机电系统 (MEMS) 压力传感器芯片作为定制应力传感器的有源元件。对传感器芯片进行了修改和封装，以保护电子系统免受生化和生物力学环境的影响。在体内植入猪椎间盘 8 周前后，对完成的传感器进行静水压力和固体接触压缩校准。对于报告的两个传感器，在 0-1.8 MPa 的范围内，应力和电压呈线性相关，灵敏度变化小于 5%。对固体接触应力的灵敏度与静水压力相当。与大多数先前的研究不同，这些传感器测量的是椎间盘核内的流体压力，而不是椎间盘核内的流体压力，这些传感器可以用于测量在相对较长的术后时间内，在大型动物的肌肉骨骼系统中典型的大小下，活体环形的动态压缩应力。
