Abstract text (incl. figure legends and references)

In the era of miniaturization, increasingly smaller devices are being produced that are mainly made of silicon. Beyond silicon, carbon shows suitable properties for applied micro- and nanostructures, such as electrical conductivity, high mechanical and chemical stability and biocompatibility. These properties are especially suitable for biosensors [1]. To realize small structures, pyrolysis can be employed to shrink by up to 90% [1]. However, the holistic pyrolysis mechanism has not yet been studied in detail. So far there is no work that investigates the property change of pyrolyzed microstructures at different atmospheric pressures. Therefore, the investigation of the properties of pyrolyzed microstructures under different atmospheric influences and different temperatures can provide insights into the pyrolysis process.

In this work, microstructures are printed on Si substrates by two-photon direct laser writing (DLW) with a commercially available photoresist (IP-Dip). These structures (see Figure 1a) are heated under a high vacuum or an inert Ar atmosphere at various pyrolysis temperatures. After pyrolysis, the shrinkage behavior of the microstructures is characterized by SEM [3], which is dependent on the surface-to-volume ratio [1]. Different geometries are considered, with varying cross-sections connecting the microelectrodes (Figure 1b). It is suggested that the electrical conductivity increases with growing pyrolysis temperature since an increasing sp² hybridization of the C-C bonds in glassy carbon dominate at higher temperatures [2]. The shrinkage behavior of the microstructures under several temperatures and environments, in correlation to the surface to volume ratio [1], is characterized. For the investigation of electrical properties, in situ-SEM nanoprobing with nanomanipulators is used to record voltage-current curves.

In the meantime, we study the influence of different environments on the mass loss. In further work, thermogravimetric analysis will be performed to determine the temperature dependent mass loss. The experimental studies will be accompanied by COMSOL simulations to predict the geometrical shrinkage behavior at other temperatures.

In summary, the study of pyrolyzed carbonaceous microstructures is an area where much research is still possible. With a better understanding of the pyrolysis process, the processes involved and the properties of glassy carbon, new technologies for medicine and industry can be found.

References:

[1] Cardenas-Benitez et. al., Microsyst. Nanoeng. 5,38 (2019).

[2] Tyler et. al., Adv. Eng. Mater. 23, 2001027 (2021).

[3] Sun et. al., Microsc. Microanal. 27 (Suppl 2), 2021.

[4] The authors acknowledge financial funding by the German Research Foundation (DFG) under Germany"s Excellence Strategy (EXC-2082/1─390761711).