Development Of Test Device For Measuring Mechanical Properties Of Bone Tissue Engineering Materials

Bone defects and its function loss caused by trauma, infection, tumor, congenital malformations etc. needs to be repaired by replacement implants. At present, though autogenous and allogenous bone grafts have been used in clinical for many years, their treating effects are not satisfactory. With the rapid development of cell culture technology, tissue engineering of bone provides a new solution to this problem. Developing an ideal bone substitute has become a major issue of concern in clinical orthopedics and tissue engineering. One of the features of tissue-engineered bone is to obtain a scaffold whose mechanical properties are similar to those of natural human bone, so the study of the mechanical properties of tissue-engineered bone substitutes has an important significance.In this paper a device for measuring the mechanical properties of tissue -engineered bone scaffolds is developed. The piezoelectric ceramic actuator is used as the driving- force device, by using its inverse piezoelectric effect and the displacement measuring device the deformation of scaffold can be regulated and controlled. The load imposed on tissue-engineered bone can be accurately measured through a load sensor installed above the loading platen. Finite element software ANSYS is employed to analyze the device modal to obtain the suitable operating frequency range of the test device.A displacement and load data acquisition/processing system is developed based on a high-speed acquisition card HK-PCI 811, and the application software written in C++ builder language. The user interface of the system is clear and convenient, and can be used for acquisition of other sensor-data through a slightly modified procedure.The dynamic mechanical properties of several tissue-engineered bone scaffolds are measured by using the newly developed mechanical test device. For all the tests, the acquired displacement and load test data processed by Origin 7.5 to obtain the dynamic stress - strain curve. By selecting the appropriate section of the elastic stress-strain curves and the starting point, the material apparent dynamic elastic modulus then be obtained by the least square data-processing method is used to get. The results of dynamic mechanical properties show that the developed testing device is suitable for measuring mechanical properties of bone tissue engineering.