Stability of plasma-enhanced atomic layer deposited barrier films in biological solutions

Abstract

The applicability of atomic layer deposited (ALD) metal oxides as protective, encapsulating barriers for bioimplants and wearable technology is tested by determining the corrosion resistance of the films. Al2O3, HfO2, TiO2, and ZrO2 are deposited at 100°C and prove to be cytocompatible through MTT cell proliferation assay measurements. Electrochemical impedance spectroscopy (EIS) measurements are conducted in phosphate buffered saline (PBS) solution, and simulated saliva and sweat solutions for 21 days using a three-electrode setup. The resulting data demonstrates the mechanism of material degradation through equivalent electrical circuits fits. Of the metal oxides tested, HfO2, TiO2, and ZrO2 are established as viable options for protective coatings by exhibiting enhanced corrosion resistance in three biological environments. ALD TiO2 is most stable in PBS solution, while ALD ZrO2 is most stable in the simulated saliva and sweat solutions.