Research Of Streaming Potentials In Bone Substitutes

One of the important characteristics of bone tissue is that it can convert its mechanical deformations into electrical signals. This is known as the electromechanical properties which including piezoelectricity and electrokinetic phenomena. The main electrokinetic phenomenon of bone is streaming potentials (SP). By now the stress-generated potentials in bone are considered to be able to accelerate the remodelling of bone. With the development of biomaterial science and implanting technique in medicine, the bone substitutes for example hydroxyapatite (HA) are used in clinic. The electromechanical compatibility of the bone substitute have an effect on the growth of the new bone tissues in the implant. So it is necessary to study the electromechanical properties of the bone substitutes.In this paper streaming potentials of the bone substitutes are measured. A modified measurement system which can be used to test SP of the material under both static load and dynamic load is developed. The modified device fit bigger pore specimens, is easy to assemble and closed hermetically better.The SPs of three groups of specimens are tested using the experiment system under multi-loading. Each group is from one bone substitutes. One material is HA made in America, the other HA made in China. The third group is CaCO3. Their pore ratio is different from each other.The results of the experiment confirm that the bone substitutes can generate SP under loading. The results are compared with the SPs of dry bone and living bone, not only the sign of measured SP is same to bone but also measured value is closed to bone. The SP under static loading is linear to static pressure and instantaneous peak value of SP is also linear to instantaneous peak value of pressure, which is consistent with the theory analysis. Bring out the form of the mathematics model describes the SP of HA by analyzing the testing data. Suppose traditional capillary formula of SP still available here, the Zeta potentials of HA made in USA and CaCO3 are calculated using the measured data and the formula.