A 1024-Channel 10-Bit 36-μW/ch CMOS ROIC for Multiplexed GFET-Only Sensor Arrays in Brain Mapping

This paper presents a 1024-channel neural read-out integrated circuit (ROIC) for solution-gated GFET sensing probes in massive muECoG brain mapping. The proposed time-domain multiplexing of GFET-only arrays enables low-cost and scalable hybrid headstages. Low-power CMOS circuits are presented for the GFET analog frontend, including a CDS mechanism to improve preamplifier noise figures and 10-bit 10-kS/s A/D conversion. The 1024-channel ROIC has been fabricated in a standard 1.8-V 0.18-mum CMOS technology with 0.012 mm 2 and 36 mu W per channel. An automated methodology for the in-situ calibration of each GFET sensor is also proposed. Experimental ROIC tests are reported using a custom FPGA-based muECoG headstage with 16times 32 and 32times 32 GFET probes in saline solution and agar substrate. Compared to state-of-art neural ROICs, this work achieves the largest scalability in hybrid platforms and it allows the recording of infra-slow neural signals

Full-bandwidth electrophysiology of seizures and epileptiform activity enabled by flexible graphene microtransistor depth neural probes

Mapping the entire frequency bandwidth of brain electrophysiological signals is of paramount importance for understanding physiological and pathological states. The ability to record simultaneously DC-shifts, infraslow oscillations (<0.1 Hz), typical local field potentials (0.1-80 Hz) and higher frequencies (80-600 Hz) using the same recording site would particularly benefit preclinical epilepsy research and could provide clinical biomarkers for improved seizure onset zone delineation. However, commonly used metal microelectrode technology suffers from instabilities that hamper the high fidelity of DC-coupled recordings, which are needed to access signals of very low frequency. In this study we used flexible graphene depth neural probes (gDNPs), consisting of a linear array of graphene microtransistors, to concurrently record DC-shifts and high-frequency neuronal activity in awake rodents. We show here that gDNPs can reliably record and map with high spatial resolution seizures, pre-ictal DC-shifts and seizure-associated spreading depolarizations together with higher frequencies through the cortical laminae to the hippocampus in a mouse model of chemically induced seizures. Moreover, we demonstrate the functionality of chronically implanted devices over 10 weeks by recording with high fidelity spontaneous spike-wave discharges and associated infraslow oscillations in a rat model of absence epilepsy. Altogether, our work highlights the suitability of this technology for in vivo electrophysiology research, and in particular epilepsy research, by allowing stable and chronic DC-coupled recordings

Flexible Graphene Solution-Gated Field-Effect Transistors : Efficient Transducers for Micro-Electrocorticography

Brain-computer interfaces and neural prostheses based on the detection of electrocorticography (ECoG) signals are rapidly growing fields of research. Several technologies are currently competing to be the first to reach the market; however, none of them fulfill yet all the requirements of the ideal interface with neurons. Thanks to its biocompatibility, low dimensionality, mechanical flexibility, and electronic properties, graphene is one of the most promising material candidates for neural interfacing. After discussing the operation of graphene solution-gated field-effect transistors (SGFET) and characterizing their performance in saline solution, it is reported here that this technology is suitable for μ-ECoG recordings through studies of spontaneous slow-wave activity, sensory-evoked responses on the visual and auditory cortices, and synchronous activity in a rat model of epilepsy. An in-depth comparison of the signal-to-noise ratio of graphene SGFETs with that of platinum black electrodes confirms that graphene SGFET technology is approaching the performance of state-of-the art neural technologies

Flexible Graphene Solution-Gated Field-Effect Transistors : Efficient Transducers for Micro-Electrocorticography

Brain-computer interfaces and neural prostheses based on the detection of electrocorticography (ECoG) signals are rapidly growing fields of research. Several technologies are currently competing to be the first to reach the market; however, none of them fulfill yet all the requirements of the ideal interface with neurons. Thanks to its biocompatibility, low dimensionality, mechanical flexibility, and electronic properties, graphene is one of the most promising material candidates for neural interfacing. After discussing the operation of graphene solution-gated field-effect transistors (SGFET) and characterizing their performance in saline solution, it is reported here that this technology is suitable for μ-ECoG recordings through studies of spontaneous slow-wave activity, sensory-evoked responses on the visual and auditory cortices, and synchronous activity in a rat model of epilepsy. An in-depth comparison of the signal-to-noise ratio of graphene SGFETs with that of platinum black electrodes confirms that graphene SGFET technology is approaching the performance of state-of-the art neural technologies

The advantages of mapping slow brain potentials using DC‐coupled graphene micro‐transistors: Clinical and translational applications

There is growing interest in examining oscillations and brain signals outside traditional EEG bands (0.3–80 Hz), as these regimes contain useful electrographic biomarkers for the diagnosis, monitoring...R.W. is funded by a Senior Research Fellowship awarded by the Worshipful Company of Pewterers. This work has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 881603 (GrapheneCore3).Peer reviewe

Novel transducers for high-channel-count neuroelectronic recording interfaces

Neuroelectronic interfaces with the nervous system are an essential technology in state-of-the-art neuroscience research aiming to uncover the fundamental working mechanisms of the brain. Progress towards increased spatio-temporal resolution has been tightly linked to the advance of microelectronics technology and novel materials. Translation of these technologies to neuroscience has resulted in multichannel neural probes and acquisition systems enabling the recording of brain signals using thousands of channels. This review provides an overview of state-of-the-art neuroelectronic technologies, with emphasis on recording site architectures which enable the implementation of addressable arrays for high-channel-count neural interfaces. In this field, active transduction mechanisms are gaining importance fueled by novel materials, as they facilitate the implementation of high density addressable arrays.This work has been funded by the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 732032(BrainCom) and Grant Agreement No. 881603 (Graphene Flagship) and co-funded by the European Regional Development Funds (ERDF) allocated to the Programa operatiu FEDER de Catalunya 2014–2020, with the support of the Secretaria d’Universitats i Recerca of the Departament d’Empresa i Coneixement of the Generalitat de Catalunya for emerging technology clusters devoted to the valorization and transfer of research results (GraphCAT 001-P-001702). The ICN2 is supported by the Severo Ochoa Centres of Excellence program, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706), and by the CERCA Program/Generalitat de Catalunya

Circuit pour le multiplexage et la lecture de données dans des réseaux de capteurs à résistance variable pour l'enregistrement massif de signaux neurones dans un dispositif implantable

An apparatus and a method using no switching elements for multiplexing and reading arrays of sensors whose electrical resistance is modulated by the signals to be measured are proposed. Sensor elements are arranged in group and columns where each column is fed with a continuous voltage waveform of different amplitude, frequency and phase characteristics which then produce current signals that are modulated by the variable resistance signals to be measured. Modulated currents are summed row-wise and collected at the read-out circuits, either by applying a constant voltage to each row of the array or by connecting a capacitor and converting these current summations into output voltage signals. The read-out circuits de-multiplex each individual sensor signal to be measured by means of lock-in demodulation according to the frequencies and phases employed for the stimulation of each column.NoConsejo Superior de Investigaciones Científicas (CSIC), Universitat Autònoma de Barcelona, Fundació Institut Català de Nanociència i Nanotecnologia (ICN2), Institució Catalana de Recerca i Estudis Avançats (ICREA)B1 Patente sin examen previ

Circuit pour le multiplexage et la lecture de données dans des réseaux de capteurs à résistance variable

An apparatus and a method using no switching elements for multiplexing and reading arrays of sensors whose electrical resistance is modulated by the signals to be measured are proposed. Sensor elements are arranged in group and columns where each column is fed with a continuous voltage waveform of different amplitude, frequency and phase characteristics which then produce current signals that are modulated by the variable resistance signals to be measured. Modulated currents are summed row-wise and collected at the read-out circuits, either by applying a constant voltage to each row of the array or by connecting a capacitor and converting these current summations into output voltage signals. The read-out circuits de-multiplex each individual sensor signal to be measured by means of lock-in demodulation according to the frequencies and phases employed for the stimulation of each column.NoConsejo Superior de Investigaciones Científicas (CSIC), Universitat Autònoma de Barcelona, Fundació Institut Català de Nanociència i Nanotecnologia (ICN2), Institució Catalana de Recerca i Estudis Avançats (ICREA)A1 Solicitud de patente con informe sobre el estado de la técnic

Circuit for the multiplexing and read-out of variable-resistance sensor arrays

An apparatus and a method using no switching elements for multiplexing and reading arrays of sensors whose electrical resistance is modulated by the signals to be measured are proposed. Sensor elements are arranged in groups and columns where each column is fed with a continuous voltage waveform of different amplitude, frequency and phase characteristics which then produce current signals that are modulated by the variable resistance signals to be measured. Modulated currents are summed row-wise and collected at the read-out circuits, either by applying a constant voltage to each row of the array or by connecting a capacitor and converting these current summations into output voltage signals. The read-out circuits de-multiplex each individual sensor signal to be measured by lock-in demodulation according to the frequencies and phases employed for the stimulation of each column.NoConsejo Superior de Investigaciones Científicas (CSIC), Universitat Autònoma de Barcelona, Fundació Institut Català de Nanociència i Nanotecnologia (ICN2), Institució Catalana de Recerca i Estudis Avançats (ICREA)A1 Solicitud de patente con informe sobre el estado de la técnic

Circuito para la multiplexación y lectura de matrices de sensores de resistencia variable para un registro neuronal masivo en un dispositivo implantable

Un procedimiento para multiplexar y demultiplexar señales de elementos de sensor en una matriz de sensores bidimensional sin utilizar elementos de conmutación, para un registro neuronal masivo en un dispositivo implantable, comprendiendo el procedimiento: para cada columna de elementos de sensor de la matriz, suministrar una forma de onda portadora armónica de voltaje continua a todos los elementos de sensor de la respectiva columna de la matriz de sensores, en el que se suministra una forma de onda portadora armónica de voltaje continua diferente a cada columna; para cada elemento de sensor, suministrar una señal al respectivo elemento de sensor, en el que se suministra una señal diferente a cada elemento de sensor; para cada fila de elementos de sensor de la matriz, leer una corriente de salida sumada de todos los elementos de sensor de la misma fila, en el que la corriente de salida sumada comprende formas de onda armónicas de corriente continuas moduladas por las señales suministradas a los elementos de sensor de la misma fila; y para cada fila de elementos de sensor en la matriz, recuperar por medio de una demodulación lock-in las señales suministradas a cada elemento de sensor en la misma fila a partir de la corriente de salida sumada de todos los elementos de sensor en la misma fila.NoConsejo Superior de Investigaciones Científicas (CSIC), Universitat Autònoma de Barcelona, Fundació Institut Català de Nanociència i Nanotecnologia (ICN2), Institució Catalana de Recerca i Estudis Avançats (ICREA)T3 Traducción de patente europe