Methodology and fabrication of adherent and crack-free SU-8 photoresist-derived carbon MEMS on fused silica transparent substrates

Abstract

Development of carbon based micro electromechanical systems (C-MEMS) has enabled the fabrication of durable, low cost and biocompatible micro devices for specific applications. Thermochemical decomposition of SU-8 (a common photoresist) is often used to fabricate C-MEMS. However, this technique has yielded unreliable results when fabrication on transparent substrates is required due to cracking and detachment of the produced carbon micro structures. We present a methodology for the fabrication of photopatterned carbon films based on SU-8 deposited on transparent fused silica substrates. Specifically, we developed and implemented this methodology for carbon microstructure fabrication derived from SU-8 2035 and SU-8 3035. It was found that SU-8 3035 derived carbon microstructures were crack free and adhered well to the substrate, while SU-8 2035 resulted in fractured and detached carbon microstructures. In addition, we characterized the produced SU-8 3035 derived carbon by measuring its electrical resistivity (1.412 ± 0.011 mΩ m), inter-structure electrical resistance, contact angle (35.7° ± 6.0°), Raman spectrum and adhesion strength to the substrate. In brief, even though SU-8 2035 and SU-8 3035 are useful materials for C-MEMS fabrication, we found that SU-8 3035 is more suitable for the fabrication of crack free and adherent carbon microstructures on transparent fused silica substrates.

Laser Pyrolysis of Imprinted Furan Pattern for the Precise Fabrication of Microsupercapacitor Electrodes

“…As demonstrated in our earlier study, a vitreous carbon mold can be successfully produced from furan by high-temperature (1000 °C) pyrolysis using an electric furnace [ 37 ]. However, when the imprinted furan micropattern (30 µm thick for this sample) was heated at the same high temperature under a nitrogen gas flow, severe cracks were generated due to the shrinkage of the furan structure by pyrolysis [ 38 ]. As shown in Figure 3 a, the furan layer delaminated from the substrate, possibly because of the weak adhesion between the carbonized film and the substrate.…”

Microfluidic devices for photo-and spectroelectrochemical applications

“…The synergistic effect of a carbon-based microelectromechanical array of interdigitated electrodes (down to 20 mm of spacing) and photopatterned SU-8 photoresist channel was also applied for resistive sensing applications (avg. resistivity of 1.412 AE 0.011 mU cm) [52]. Recently, it was manifested that microcavities in optical fibers could serve as highly functional spectroelectrochemical microanalytical devices [53].…”

A critical review on the fabrication techniques that can enable higher throughput in dielectrophoresis devices

“…Those that do are usually more expensive than the common float glass used in other approaches to fabricate DEP devices. Common substrates when implementing carbon electrodes are opaque silicon, with or without silicon oxide coating, and fused silica [78,79]. For comparison, in 2019, a 4-inch wafer of borofloat glass was roughly 20-30% of the cost of a silicon or fused silica wafer.…”