Revealing the functional connectivity in natural neuronal networks is central to understanding circuits in the brain. Here, we show that silicon nanowire field-effect transistor (Si NWFET) arrays fabricated on transparent substrates can be reliably interfaced to acute brain slices. NWFET arrays were readily designed to record across a wide range of length scales, while the transparent device chips enabled imaging of individual cell bodies and identification of areas of healthy neurons at both upper and lower tissue surfaces. Simultaneous NWFET and patch clamp studies enabled unambiguous identification of action potential signals, with additional features detected at earlier times by the nanodevices. NWFET recording at different positions in the absence and presence of synaptic and ion-channel blockers enabled assignment of these features to presynaptic firing and postsynaptic depolarization from regions either close to somata or abundant in dendritic projections. In all cases, the NWFET signal amplitudes were from 0.3–3 mV. In contrast to conventional multielectrode array measurements, the small active surface of the NWFET devices, ∼0.06 μm2, provides highly localized multiplexed measurements of neuronal activities with demonstrated sub-millisecond temporal resolution and, significantly, better than 30 μm spatial resolution. In addition, multiplexed mapping with 2D NWFET arrays revealed spatially heterogeneous functional connectivity in the olfactory cortex with a resolution surpassing substantially previous electrical recording techniques. Our demonstration of simultaneous high temporal and spatial resolution recording, as well as mapping of functional connectivity, suggest that NWFETs can become a powerful platform for studying neural circuits in the brain.
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I first observed nerve cells and silicon wafers while working on two distinctly different degree dissertations in my laboratory at the University of Ulm in 1984. At the time, we were studying how the electrical activity of nerve cells influenced fluorescent dyesand the effects of artificial membrane layers on microscopic silicon electrodes. Enthused by the results, I used the occasion of the 20th Winter Seminar “Molecules, Information and Memory” presented by Manfred Eigen in January 1985 to present a paper entitled Brain on Line? The Feasibility of a Neuron-Silicon Junction, Read more
Cell-semiconductor hybrid systems have potential to become important for the discovery of new pharmaceuticals and for use as whole cell sensors in drug screening. In addition it is feasible that they will be the future building blocks of artificial neuronal networks and that they will play a key role in interfacing traumatized nerves. The interface between live cells and solid state physics is one of the key issues of this work and is an important topic of our research. In order to bio-functionalise a solid surface in a way that the cell can recognize it as an adequate partner we have developed a broad range of experimental techniques to both modify and analyse this interface. To avoid atrophy of the cells and to control the cell-substrate coupling the device surface can be modified by the deposition of ultrathin polymer films. Using this approach the exploration of the development and plasticity of electrical interactions between single cells is feasible by a convenient non-destructive method of maintaining long term electrical contact with cultured cells, at a large number of recording sites. This project will be focussing on various topics: for drug discovery using genetically modified cells as transducer elements for molecular signals, studying the spatio-temporal signal spreading in two-dimensional cell monolayers (cardiac myocytes), and building up two-dimensional neuronal networks.