Structural anti-reflective coating and bactericidal surfaces, as well as many other effects, rely on high-aspect-ratio (HAR) micro- and nanostructures, and thus, are of great interest for a wide range of applications. To date, there is no widespread fabrication of dense or isolated HAR nanopillars based on UV nanoimprint lithography (UV-NIL). In addition, little research on fabricating isolated HAR nanopillars via UV-NIL exists. In this work, we investigated the mastering and replication of HAR nanopillars with the smallest possible diameters for dense and isolated arrangements. For this purpose, a UV-based nanoimprint lithography process was developed. Stability investigations with capillary forces were performed and compared with simulations. Finally, strategies were developed in order to increase the stability of imprinted nanopillars or to convert them into nanoelectrodes. We present UV-NIL replication of pillars with aspect ratios reaching up to 15 with tip diameters down to 35 nm for the first time. We show that the stability could be increased by a factor of 58 when coating them with a 20 nm gold layer and by a factor of 164 when adding an additional 20 nm thick layer of SiN. The coating of the imprints significantly improved the stability of the nanopillars, thus making them interesting for a wide range of applications.
In vitro diagnostic devices have highly esteemed platforms for toxicological testing, drug screening and even for theranostics. An extremely promising device type are microstructured devices, often referred to as biochips, that can be coupled with in vitro cell cultures. Employing microfluidic structures devices such as cell-chips and organ-on-a-chip devices have been developed to mimic the microenvironment of the human body. By implementing microelectrodes on the chip it is facile to utilize the benefits of microelectronics - the label-free, non-destructive, permanent real-time measurement of cellular processes.
With electretic cells the action potential of cells can be directly measured, while other non-electrically cells can be measureds via their impedance. We will present devices on both concepts from our research. We will present sophisticated biomedical devices, were used to record the electrophysiological activity the neurite part of nerve cells of in real-time. With an axon isolation device a delicate microfluidics system is combined with microelectrodes inside of microchannels just large enough for axonal and dendritic structures.
Also the biocompatibility of electrode materials is essential, and the relevance of cyclic voltammetry for checking the safe voltage range of microelecrtrodes will be explained with practical examples. Fabrication routes, benefits and limitations of microelectrode arrays. interdigitated electrode sensors and even 3D nanoelectrodedes will be discussed.
An outlook on future devices featuring arrays 3D nanoelectrodes and microstructured guidance structures will be given.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.