Implantable Microelectronic Devices for Measuring In vivo Corrosion Rates

Open Access
Bimber, Beth Anna
Area of Honors:
Engineering Science
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Barbara Shaw, Thesis Supervisor
  • Charles E Bakis, Honors Advisor
  • Judith A Todd, Faculty Reader
  • Elizabeth Sikora, Faculty Reader
  • corrosion
  • magnesium
  • microelectronic device
  • implant
Medical implants have been around for thousands of years. However, the idea of biodegradable medical implants, for use as coronary stents or bone plates, is more recent. The corrosion properties of magnesium, along with the fact that it is already needed in the human body, make it a good candidate for a biodegradable implant material. However, pure magnesium corrodes too fast, so this material needs to be alloyed. Varying weight percent additions of titanium were alloyed with magnesium to create a spectrum of physical vapor deposited Mg-Ti alloys. The alloys are electrochemically tested using open circuit potential, polarization resistance, and EIS experiments to determine the specific corrosion rates in vitro. The in vitro corrosion rates allow the varying alloys to be compared, to determine the best corrosion rate. As much as the in vitro corrosion rate provides information about how the alloy will act in a corrosive environment, in vivo corrosion data is needed. A method for measuring the in vivo corrosion rates needs to be created. An implantable microelectronic device with a working, counter, and reference electrode on a micro-sized scale can solve the problem of how to measure the specific in vivo corrosion rate. Currently, there are still issues to the specific processing in the manufacturing of said device, such as the lift-off process of the working electrode. Further research will solve this problem, since the implications of in vivo corrosion data can implemented in biodegradable coronary stents and bone plates.