Abstract
3D interdigitated pyrolytic carbon microelectrodes (3D IDE) with high complexity and interconnectivity were fabricated taking advantage of suspended interdigitated microstructures. A novel fabrication method for a 3D interdigitated polymer precursor template was developed based on a dual photoresist process including multiple UV exposures at two different wavelengths. The precursor structures were subsequently pyrolyzed at 1100°C for 1 h in N2 environment to obtain 3D interdigitated carbon microelectrodes. Different 3D electrode designs were fabricated and the electrochemical performance was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). 3D IDE with smaller structural dimensions displayed ultra-microelectrode (UME)-like behavior with a sigmoidal shape of the cyclic voltammograms (CV) and the absence of the linear diffusion regime in EIS. Furthermore, the 3D IDE displayed 2-fold higher peak currents in CV and significantly reduced charge transfer resistance compared to 2D IDE.
Highlights
Interdigitated electrodes (IDE) typically consist of two closely spaced individually addressable electrodes with interdigitated comb-like structure
The fabrication of suspended 3D interdigitated pyrolytic carbon microelectrodes (3D IDE) precursor structures with mr-DWL-40 photoresist supported by SU-8 micropillars patterned on 2D bottom IDE was successfully implemented
Pyrolysis of the structures resulted in highly interdigitated 3D pyrolytic carbon microelectrodes
Summary
Interdigitated electrodes (IDE) typically consist of two closely spaced individually addressable electrodes with interdigitated comb-like structure. Several techniques have been proposed to fabricate IDE such as photolithography [22e24], screen printing [25], inkjet printing [26], laser writing [27,28] and hot embossing [29,30]. These approaches are limited to planar (2D) electrode fabrication. For the electrochemical applications mentioned above, the performance is typically improved by increasing the electrode surface area, which can be achieved by integration of 3D electrode structures. 3D printing with commercial systems still lacks the resolution to achieve structures with dimensional features below a few 10s of microns and electroplating of metals on 3D substrates can involve an expensive and lengthy fabrication process
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