Potential step impedance analysis was utilized to evaluate the electrochemical impedance of commercially pure titanium (cpTi) samples that were polarized to static potentials (range from 21000 mV to +1000 mV vs. Ag/AgCl) and immersed in physiologically relevant electrolytes [phosphate buffered saline (PBS) and cell culture medium with 10% fetal bovine serum (AMEM + FBS)] for 24 hrs. The cpTi impedance outcomes were a complex function of voltage, solution constituents, and immersion time. In the 0 mV to +1000 mV range, oxide growth was observed over 24 hr immersion in both solutions based on decreasing current density (∼10-6 A/cm2 to ∼10-8 A/cm 2) and increasing Rp (200 kΩ cm2 to ∼10 MΩ cm2). Below 0 mV, the 24 hr Rp decreased with negative potential to ∼15 kX cm2. After 24 hr immersion, oxide dissolution and/or adsorption of organic species caused the capacitance to increase at -1000 mV (AMEM + FBS & PBS) and at -600 mV (AMEM + FBS only). Twenty-four hours of immersion in AMEM + FBS at -1000 mV and -600 mV produced a surface coloration that is likely due to alteration of oxide valance state and/or doping level. This work shows that Ti surface oxide and its electrochemical behavior can be altered dramatically under sustained cathodic potentials.
|Number of pages||7|
|Journal||Journal of Biomedical Materials Research - Part B Applied Biomaterials|
|State||Published - Apr 2010|
- Electrochemical impedance
- Voltage effects