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Objective. The development of experimental methodology utilizing graphene micro-transistor arrays to facilitate and advance translational research into cortical spreading depression (CSD) in the awake brain. Approach. CSDs were reliably induced in awake nontransgenic mice using optogenetic methods. High-fidelity DC-coupled electrophysiological mapping of propagating CSDs was obtained using flexible arrays of graphene soultion-gated field-effect transistors (gSGFETs). Main results. Viral vectors targetted channelrhopsin expression in neurons of the motor cortex resulting in a transduction volume 1 mm3. 5-10 s of continous blue light stimulation induced CSD that propagated across the cortex at a velocity of 3.0 0.1 mm min-1. Graphene micro-transistor arrays enabled high-density mapping of infraslow activity correlated with neuronal activity suppression across multiple frequency bands during both CSD initiation and propagation. Localized differences in the CSD waveform could be detected and categorized into distinct clusters demonstrating the spatial resolution advantages of DC-coupled recordings. We exploited the reliable and repeatable induction of CSDs using this preparation to perform proof-of-principle pharmacological interrogation studies using NMDA antagonists. MK801 (3 mg kg-1) suppressed CSD induction and propagation, an effect mirrored, albeit transiently, by ketamine (15 mg kg-1), thus demonstrating this models' applicability as a preclinical drug screening platform. Finally, we report that CSDs could be detected through the skull using graphene micro-transistors, highlighting additional advantages and future applications of this technology. Significance. CSD is thought to contribute to the pathophysiology of several neurological diseases. CSD research will benefit from technological advances that permit high density electrophysiological mapping of the CSD waveform and propagation across the cortex. We report an in vivo assay that permits minimally invasive

We present a simple approach for DNA detection which profits from the use of miniaturized carbon nanotube (CNT) electrodes, Ru(NH 3) 6 2+/3+ as redox DNA hybridization reporters and sensitive but simple electrochemical techniques (chronocoulometry and impedance spectroscopy). The manufacturing process employed in this work yielded robust, highly controlled and well-defined microelectrode arrays of vertically aligned multi-walled CNTs which facilitated very reproducible electroanalytical measurements. The hybridization process and its efficiency were monitored and quantified with chronocoulometric measurements by following up the Ru(NH 3) 6 2+/3+ adsorption at the DNA phosphate backbone. Limits of detection of 1 nM and an efficiency of nearly 100% were found with such methodology. One of the advantages of using CNT microelectrodes is that the scaling down of the electrode size allows the impedimetric detection with such highly positively charged redox reporters, using the charge transfer resistance as an indicator of the DNA hybridization. Such detection scheme would not have been possible in macroscopic CNT electrodes due to the dominance of the diffusion controlled processes. Limits of detection of 100 pM were achieved using the impedimetric technique. The combination of the miniaturized and robust CNT-based electrodes, the advantages of the chosen redox reporter and the electrochemical techniques provide a very simple, reproducible and efficient strategy that could facilitate genosensing and diagnosis. © 2011 Elsevier B.V. All rights reserved.

A technology to address massive and batch fabrication of carbon nanotube field effect transistors (CNT-FET) based systems at wafer level is presented. In order to demonstrate the feasibility of the technology, we have designed, fabricated, tested and evaluated a CNT-FET based monitor chip. The monitor chip is composed of 16 different in design CNT-FET structures. In total, each monitor chip contains 5760 devices. Each wafer is composed of 24 monitor chips. Evaluation of the data obtained through automatic test procedures gives evidence of the fabrication of more than 10,000 functional CNT-FET on a 4 inch wafer. A yield of functional CNT-FET of 27% has been achieved for optimal designs.

We report on the specialised characterization of the local electron beam irradiation of carbon nanotube (CNT) based devices motivated by previous studies on device electrical characteristics. In particular, Kelvin probe force microscopy provides surface potential description of the device under exposure. The experimental characterization is complemented with 3-dimensional electric field modelling of the devices using finite element methods. The modelling includes the effect of electron charging and AFM tip potential. Comparison of simulation and experiments shows good agreement and contributes to assess the distortion of electrical characteristics of CNT based devices under electron beam irradiation. © 2007 Elsevier B.V. All rights reserved.