Osseous implant for studies of biomaterials using an in vivo electrochemical transducer

The in vitro and in vivo electrochemical behavior of commercially pure titanium (cp Ti) was characterized using a specialized osseous implant in conjunction with electrochemical impedance spectroscopy (EIS) measurement techniques. Studies performed in vitro were used to verify the operation of the transducer and develop methods of deconvoluting EIS data. This method was subsequently used to describe an electrochemical equivalent circuit model of the surface oxide and electrical double-layer capacitance of cp Ti in the endogenous electrolyte found in the medullary compartment of a baboon tibia. Kinetic profiles of the double-layer capacitance and the polarization resistance were constructed from multiple in vitro and in vivo EIS measurements performed over 60 min at 0 V (reference Ag/AgCI) conditioning potential. The profiles demonstrated that the growth of surface oxides was biphasic, with rapid decrease in the double-layer capacitance occurring within 20 min and reaching steady-state conditions at approximately 40 min. These data suggested that a passive, stable biofilm formed on the cp Ti surface in vivo and in vitro.