In this paper, three-dimensional (3D) porous carbon interdigitated electrode arrays (IDEAs) are developed utilizing standard photolithography of electrospun mats of SU-8 photoresist nanofibers. Porous IDEAs have the potential to produce higher aspect ratio than non-porous electrode due to the reduced stress at the interface between the substrate and the carbon structure [1]. In a first step, a layer of polymeric nanofibers is deposited on a silicon substrate by optimizing the conditions for far-field electrospinning of SU-8 photoresist. Subsequently, the SU-8 mat is patterned using conventional photolithography to generate the polymer precursor for the carbon electrode structure. Finally, the polymer precursor is pyrolysed at 900°C in an inert atmosphere to produce a porous carbon IDEA [2]. The porous carbon IDEAs were optimized as a function of the nanofibers diameter, thickness of the electrospun SU-8 mat and width/gap ratio of the IDEAs. To characterize the porous carbon IDEAs, electrochemistry studies (cyclic voltammetry and electrical impedance spectroscopy) were conducted and the results were compared with traditional flat carbon IDEAs (the latter was fabricated by spin coating a non-porous SU-8 film on a silicon substrate).  The redox amplification factor of both porous and flat carbon IDEAs was studied to gain an understanding of the effect of electrode porosity on the redox amplification. This factor was optimized for width and gap of the IDEAs and the nanofibers diameter.

 

Acknowledgments

This research is supported by Flagship grant project number FL001A-14AET, Transdisiplinary Research Grant Scheme (TRGS TR002A-2014B) from University of Malaya and Ministry of Science Technology and Innovation (MOSTI) Science Fund (SF-020-2014).

 

References

1.         Sharma, C.S., A. Sharma, and M. Madou, Multiscale carbon structures fabricated by direct micropatterning of electrospun mats of SU-8 photoresist nanofibers. Langmuir, 2010. 26(4): p. 2218-2222.

2.         Kamath, R.R. and M.J. Madou, Three-Dimensional Carbon Interdigitated Electrode Arrays for Redox-Amplification. Analytical chemistry, 2014. 86(6): p. 2963-2971.