High temperature SU-8 pyrolysis for fabrication of carbon electrodes

Abstract

In this work, we present the investigation of the pyrolysis parameters at high temperature (1100ºC) for the fabrication of two-dimensional pyrolytic carbon electrodes. The electrodes were fabricated by pyrolysis of lithographically patterned negative epoxy based photoresist SU-8. A central composite experimental design was used to identify the influence of dwell time at the highest pyrolysis temperature and heating rate on electrical, electrochemical and structural properties of the pyrolytic carbon: Van der Pauw sheet resistance measurements, cyclic voltammetry, electrochemical impedance spectroscopy and Raman spectroscopy were used to characterize the pyrolytic carbon. The results show that the temperature increase from 900ºC to 1100ºC improves the electrical and electrochemical properties. At 1100ºC, longer dwell time leads to lower resistivity, while the variation of the pyrolysis parameters has small influence on electrochemical performance.

Electrochemical Monitoring of Saos‐2 Cell Differentiation on Pyrolytic Carbon Electrodes

“…The spectra can be fitted to a modified Randles model , which models a cell where the polarization is due to a combination of diffusion and kinetic processes. The behavior reported here is in accordance with what was previously observed for 2D pyrolytic carbon electrodes obtained with the same pyrolysis conditions taking into account the effective area of the WE .…”

“…All the experiments were performed using two dimensional (2D dots) pyrolytic carbon electrode chips obtained through an optimized pyrolysis process of lithographically patterned epoxy based photoresist SU‐8 (Microresist GmbH, Germany) . The 2D dots electrode chips (10 mm×30 mm) consist of a carbon working electrode (WE), surrounded by a carbon counter electrode (CE).…”

“…The passivation layer extends to the WE, displaying 19 circular openings with a diameter of 250 μm (Figure ). The electrode design was chosen due to the smaller electrode area, compared to 2D electrodes without passivation layer on the WE . The area reduction leads to a higher sensitivity towards changes detectable at the electrode‐solution interface and hence at the interface between electrode and cell layer .…”

“…Before the measurements all the chips were subjected for 65 s to an oxygen plasma treatment (0.5 bar) in an Atto Plasma System (Diener electronic, Germany) with a power of 50 W to improve wettability . In all the experiments the electrodes were placed in a PMMA‐based self‐aligning magnetic clamping system, which defines a well with a volume of 300 μL . Cyclic voltammograms were recorded using a three electrode configuration, scanning the potential from −600 mV to 600 mV with a scan rate of 100 mV/s.…”

Bioimpedance Measurements on Human Neural Stem Cells as a Benchmark for the Development of Smart Mobile Biomedical Applications

“…The pyrolytic carbon electrode chips were provided by Technical University of Denmark [19]. They are composed of a circular pyrolytic carbon working electrode (WE) with an area of 12.5 mm 2 , surrounded by a platinum counter electrode (CE) with an area of 25.2 mm 2 .…”