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Neuroelectronics

Research in neuroelectronics is centered on experiments at the cellular level, using micro- and nanofabrication, molecular biology, in vitro cell culture and microfluidic methods. We aim to develop an experimental platform which allows us to control neuronal interactions on the microscale in combination with localized sensing and stimulation capabilities by electrical and optical means for the investigation of signal processing on micro – and macro circuits.

Engineering microstructured Neuronal Networks

Engineering of microstructured approaches enable a define controlling of neuronal network formation. Using Microcontact printing and microgradient methods allows reducing the complexity of the brain to address single cell function and control neuronal interactions. We aim to mimick neuronal pathways by microfluidic systems with predefined microstructures to polarize and synchronize neuronal networks and to develop neuronal 3D cultures to recapitulate the complexity and functionality of in vivo neural circuits.

Controlling network formation at the single cell level

Controlling network formation at the single cell level

Networks of neurons with controlled connectivity are needed for fundamental studies in neuronal signal processing and applications like neurodegeneration. This requires efficient, directed and long lasting control of axon and dendrites growths toward their targets. Best results so far could be achieved by microcontact printing of biomolecules. More: Controlling network formation at the single cell level …

Biomimicking model of a neuronal pathway

Biomimicking model of a neuronal pathway

A new brain-on-a-chip system for in vitro studies of propagative neuronal disorders is developed, that allows to mimic brain pathways to investigate cellular mechanisms underlying synaptic and neuronal dysfunction. The combination of microfluidic and Multi-Electrode Array (MEA) allows localized sensing of signal characteristics in a defined micro circuit.
The microfluidic platform enables a cocultivating of cortico-striatal networks separated by predefined microchannels, which provide an orientated axonal growth and lead to interaction possibilities. Our aim is to learn more about the Alzheimer's disease, which is mainly associated with the degeneration of the cortico-striatal brain pathway. More: Biomimicking model of a neuronal pathway …

Development of neuronal 3D cultures

Development of neuronal 3D cultures

Our research focus on the development of 3D culture systems which potentially offer higher degrees of organization and advanced physiological characteristics, for instance mechanical properties as found in tissues and organs. This new culture system provides a valuable in vitro tool to investigate neural cell-cell and cell-substrate interactions in a three-dimensional environment and signal processing that will be of higher biological relevance. More: Development of neuronal 3D cultures …

Design and Characterization of the Cell Device Interface

Extracellular stimulation and recording is extremely affected by the electrode–cell interface, since it influences signal amplitude and shape as well as noise levels. These drawbacks can be overcome by optimizing the electrode–cell interface and decreasing the spatial gap in order to increase the electrode–cell seal resistance. To overcome these limitations, we apply biomimetic approaches as well as 3D microstructures to induce a very close and tight contact of the cell on to the electrode.

Characterizing_cell_device_interface

Characterizing the cell device interface

Aim of this activity is the understanding of cell device interfaces, in particular its interaction with surface topography and chemistry using techniques with nanometer resolution in lateral and axial directions. For this we use surface plasmon resonance (SPR) imaging applying two modes: lens-imaging-type surface (LISPM) and scanning localized surface (SLSPM) plasmon microscopy. This allows imaging of subcellular features of single adherent cells. The resolution can be improved via electron microscopy, however this requires artifact-free transition of living cells into the ultrahigh vacuum. Besides critical point drying (CPD) a resin embedding procedure is developed which allows to access the surface morphology while imaging single cells on planar and 3D nanostructured surfaces prepared by focus ion beam (FIB) technique. More: Characterizing the cell device interface …

Engineering the interface

Engineering the interface

Developing neuroelectronic hybrids require a deep understanding of the interactions taking place at the cell-device interface. While standard routes involve (bio)chemical functionalization of the surface, our approach emphasizes on biomimetic, low modulus elastic materials as well as topographic features for improving neuron-device interactions. Supported lipid bilayers (SLBs) with embedded cell adhesion and synapse related proteins can be used as biomimetic substrates for neuronal cell culture. A better and more compliant match to the soft brain cells can be obtained by using low modulus elastic materials. Nanotopological cues also play a crucial role in mediating cell attachment, orientation and biocompatibility. More: Engineering the interface …

3D structures & Nanocavities

3D structures & Nanocavities

To improve impedance and cell attachment to extracellular electrodes at the same time, 3D structures are produced on metal electrodes. We investigate recessed nano-cavities, cylindrical pillars, mushroom-like pillars with a cap, and straws to determine the optimal aspect ratio and shape for engulfment by the cell. More: 3D structures & Nanocavities …

Carbon-based materials

Carbon-based materials

Carbon materials are more bioinert than traditional metals and semiconductors. We investigate the use of diamond, graphene, and conductive polymers as microelectrodes. Organic materials are also used to make flexible devices for example with graphene on thin polymer substrates. Graphene can also be used as the channel material in solution gated Field Effect Transistors for detecting cell action potentials. More: Carbon-based materials …

Recording and stimulation of cellular activity

In order to investigate information processing in neuronal networks, action potential firing must be observed and manipulated. We employ various methods to detect and stimulate neural activity. Stimulation and detection is often the most powerful when complimentary techniques are employed, so that the observation of stimulation artefacts is minimized. Therefore, we combine:

Electrical methods

Electrical methods

In order to establish a “communication” with neuronal networks one must be able to "listen" first. Neurons are electrogenic cells, which produce electronic potentials, so-called action potentials (APs). These APs are the building blocks of neuronal communication and thus brain activity. Being able to record and stimulate the APs paves the way for understanding the brain on a deeper level. Modern micro/nano-electronics provide us with a set of devices to fulfil this purpose, starting with patch-clamp and microelectrode arrays (MEAs) and moving towards transistors and miniaturization. More: Electrical methods …

Optical methods

Optical methods

The firing of an action potential is accompanied by an influx of calcium ions into the cell. These can be detected by fluorescent dyes (ie. Fluo-4) or genetically encoded fluorescent proteins that bind calcium (GcAMP), allowing video recording of neural activity. More: Optical methods …

Optogenetic methods

Optogenetic methods

The light sensitive proteins Channelrhodopsin 2, from C. reinhardtii, and GtACR1 from G. theta depolarize or hyperpolarize neurons when illuminated. Photo-responsive ion channels can be selectively expressed in cortical neurons using recombinant adeno-associated virus particles to deliver the genes. Cell activity can then be measured using our chip based technology for days without harming the cell while the activity of the network is manipulated with light. More: Optogenetic methods …


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