Date Published: February 23, 2018
Publisher: Public Library of Science
Author(s): Matthias Schürmann, Norman Shepheard, Natalie Frese, Kevin Geishendorf, Holger Sudhoff, Armin Gölzhäuser, Ulrich Rückert, Christian Kaltschmidt, Barbara Kaltschmidt, Andy Thomas, Dario Pisignano.
In this manuscript, we first reveal a simple ultra violet laser lithographic method to design and produce plain tailored multielectrode arrays. Secondly, we use the same lithographic setup for surface patterning to enable controlled attachment of primary neuronal cells and help neurite guidance. For multielectrode array production, we used flat borosilicate glass directly structured with the laser lithography system. The multi layered electrode system consists of a layer of titanium coated with a layer of di-titanium nitride. Finally, these electrodes are covered with silicon nitride for insulation. The quality of the custom made multielectrode arrays was investigated by light microscopy, electron microscopy and X-ray diffraction. The performance was verified by the detection of action potentials of primary neurons. The electrical noise of the custom-made MEA was equal to commercially available multielectrode arrays. Additionally, we demonstrated that structured coating with poly lysine, obtained with the aid of the same lithographic system, could be used to attach and guide neurons to designed structures. The process of neuron attachment and neurite guidance was investigated by light microscopy and charged particle microscopy.
The characteristic feature of a neuron is its capability to generate and propagate action potentials. In this manner, these electrically excitable cells fulfill their main purpose by transmitting and processing information in the neuronal networks drawn through the organism (Fig 1A).
We demonstrate an opportunity to equip MEAs with chemical coating to enable electrophysiological measurements on an arranged neuronal network. The presented method for customized production of MEAs using laser UV-lithography offers a row of advantages. Compared to standard contact lithography, no photomask is needed for the laser lithography. This is advantageous in terms of the processing rate of our MEA production process, since several lithographic applications are required and a manual alignment of different masks would otherwise be necessary during every step. Besides, laser lithography works on several length scales. The smallest printable feature is approximately 1 μm in size. The area printed during the first lithography step is about 39 mm by 39 mm. The major advantage is easy adaptability of the CAD controlled laser lithographic system used in this study. This enables an easy alteration and high flexibility of the MEAs layout. This is of outmost importance in basic research where experimental setup changes frequently. In this context, layouts with two different electrode arrangements and an electrode diameter of 30 μm with an electrode spacing of 200 μm were chosen. For example, further downscaling of the electrodes can easily be achieved with the described methods, but the electrode spacing should be altered simultaneously, with respect to the range of the received signals.