Investigation of Interface Bonding Mechanisms between Glassy Carbon Microelectrodes and Polyimide Substrate through Fourier Transform Infrared Spectroscopy
Mieko Hirabayashi, Kyle Logan, Christopher P. Deutschman, Thomas W. McDowell, Martha Z. Torres, David Pullman, Sam Kassegne
With increasing innovations in lithographically patterned glassy carbon (GC) microstructures supported on a flexible polyimide substrate, interest in understanding the nature and strength of the interface between these two materials has come to the forefront. However, although polyimide and glassy carbon have been both extensively studied independently, interface bonds between them in a composite structure have not been investigated. The work presented here investigates the interaction between GC and polyimide at their interface by comparing the infrared spectrum of the composite microstructures (GC bonded to polyimide) to the spectra of both materials alone. A significant difference in the hydroxyl and anhydride peaks between the polyimide, carbon, and composite was found, indicating the presence of not only hydrogen bonding, but also covalent bonding in the composite microstructure. Functionalization of GC through oxygen plasma etching and annealing above 200°C was observed to result in the formation of additional anhydrides. We submit that the presence of these sets of strong covalent bonds opens vast opportunities for a wider usage of variety of robust GC microstructures supported on polyimide substrate.