2048 action potential recording channels with 2.4 μVrms noise and stimulation artifact suppression

Viswam, Vijay; Chen, Yihui; Shadmani, Amir; Dragaš, Jelena; Bounik, Raziyeh; Radivojević, Miloš; Müller, Jan; Hierlemann, Andreas

doi:10.1109/biocas.2016.7833750

Cited by 9 publications

(12 citation statements)

References 8 publications

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“…Saturation can be prevented by increasing the amplifier linear input range and tolerance to d.c. current offset 21,26,46 , or by subtracting the large amplitude components of the artefact 47,48 . Artefact duration can be reduced by rapidly clearing charge built up on circuit elements from stimulation 25,26,49,50 . We have designed the NMICs with improved stimulation and recording architectures to both prevent large indirect artefacts and minimize their effects on the front-end circuits.…”

Section: System Designmentioning

confidence: 99%

A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates

et al. 2018

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losed-loop neuromodulation improves open-loop therapeutic electrical stimulation by providing adaptive, on-demand therapy, reducing side effects and extending battery life in wireless devices 1,2. Closing the loop requires low-latency extraction and accurate estimation of neural biomarkers 3-5 from recorded signals to automatically adjust when and how to administer stimulation as feedback to the brain. Recent studies have shown responsive stimulation to be a viable option for treating epilepsy 2,6 , and there is evidence that closed-loop strategies could improve deep brain stimulation (DBS) for treating Parkinson's disease and other motor disorders 7,8. However, there is presently no commercial device allowing closed-loop stimulation for DBS in patients with movement disorders, and strategies for implementing such stimulation are still under investigation. In fact, most attempts to close the loop for DBS treatments have been done only for short duration using systems that were not fully implantable 4,5,9-11. To enable advanced research in closed-loop neuromodulation, there is a need for a flexible research platform, for testing and implementing these various closed-loop paradigms, that is also wireless, compact, robust and safe. Designing such a device requires unification of multi-channel recording, biomarker detection and microstimulation technologies into a single unit with careful consideration of their interactions. Wireless, multi-channel recording-only devices capture activity from wide neuronal populations 12,13 , but do not have the built-in ability to immediately act on that information and deliver stimulation. Several complete closed-loop devices have been proposed and demonstrated, but are limited by low channel counts 14-17 and low wireless streaming bandwidth 14-18. Most recently, variations of the fully integrated and optimized closed-loop neuromodulation system-on-a-chip (SoC) have been presented, but full system functionality has not yet been adequately demonstrated in vivo 19-25. While future versions may be paired with miniaturized external battery packs and controllers, current systems built around these SoCs require large, stationary devices to deliver power inductively from a close range 19,21,23. This limits studies to using small, caged animals. Furthermore, any device for concurrent sensing and stimulation must be able to mitigate or remove stimulation artefactsthe large voltage transients resulting from stimulation that distort recorded signals and obscure neural biomarkers. Signals recorded concurrently with stimulation may contain relevant information for closed-loop algorithms or offline analysis, yet existing devices disregard these affected windows of data, or fail to reduce artefacts to an acceptable level for recovery of many potentially useful biomarker features. Effectively and efficiently cancelling artefacts requires careful co-design of the stimulators and signal acquisition chains. Additionally, computational reprogrammability is needed for application-dependent algorithm de...

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Section: System Designmentioning

confidence: 99%

A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates

et al. 2018

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“…Although conventional pseudo-resistor structures can achieve such large resistances, the resistance spreads are large due to process and temperature variations. To overcome this drawback, we devised two novel structures [6, 39], shown in Fig. 4.…”

Section: Circuit Implementationmentioning

confidence: 99%

Stimulation and Artifact-Suppression Techniques for In Vitro High-Density Microelectrode Array Systems

Shadmani

Viswam

Chen

et al. 2019

IEEE Trans. Biomed. Eng.

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We present novel voltage stimulation buffers with controlled output current, along with recording circuits featuring adjustable high-pass cut-off filtering to perform efficient stimulation while actively suppressing stimulation artifacts in high-density microelectrode arrays. Owing to the dense packing and close proximity of the electrodes in such systems, a stimulation through one electrode can cause large electrical artifacts on neighboring electrodes that easily saturate the corresponding recording amplifiers. To suppress such artifacts, the high-pass corner frequencies of all available 2048 recording channels can be raised from several Hz to several kHz by applying a “soft-reset” or pole-shifting technique. With the implemented artifact suppression technique, the saturation time of the recording circuits, connected to electrodes in immediate vicinity to the stimulation site, could be reduced to less than 150 μs. For the stimulation buffer, we developed a circuit, which can operate in two modes: either control of only the stimulation voltage, or control of current and voltage during stimulation. The voltage-only controlled mode employs a local common-mode feedback operational transconductance amplifier with a near rail-to-rail input/output range, suitable for driving high capacitive loads. The current/voltage controlled mode is based on a positive current conveyor generating adjustable output currents, while its upper and lower output voltages are limited by two feedback loops. The current/voltage controlled circuit can generate stimulation pulses up to 30 μA with less than ±0.1% linearity error in the low-current mode, and up to 300 μA with less than ±0.2% linearity error in the high-current mode.

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“…The total gain can be programmed in steps of 6 dB from 29 dB to 77 dB. For a detailed description of the AP-recording channel, please refer to [11][20][21].…”

Section: System Designmentioning

confidence: 99%

Impedance Spectroscopy and Electrophysiological Imaging of Cells With a High-Density CMOS Microelectrode Array System

Viswam

Bounik

Shadmani

et al. 2018

IEEE Trans. Biomed. Circuits Syst.

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A monolithic multi-functional CMOS microelectrode array system was developed that enables label-free electrochemical impedance spectroscopy of cells in-vitro at high spatiotemporal resolution. The electrode array includes 59,760 platinum microelectrodes, densely packed within a 4.5 mm×2.5 mm sensing region at a pitch of 13.5 μm. 32 on-chip lock-in amplifiers can be used to measure the impedance of any arbitrarily chosen subset of electrodes in the array. A sinusoidal voltage, generated by an on-chip waveform generator with a frequency range from 1 Hz to 1 MHz, was applied to the reference electrode. The sensing currents through the selected recording electrodes were amplified, demodulated, filtered and digitized to obtain the magnitude and phase information of the respective impedances. The circuitry consumes only 412 μW at 3.3 V supply voltage and occupies only 0.1 mm2, for each channel. The system also included 2048 extracellular action-potential recording channels on the same chip. Proof of concept measurements of electrical impedance imaging and electrophysiology recording of cardiac cells and brain slices are demonstrated in this paper. Optical and impedance images showed a strong correlation.

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2048 action potential recording channels with 2.4 μVrms noise and stimulation artifact suppression

Cited by 9 publications

References 8 publications

A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates

A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates

Stimulation and Artifact-Suppression Techniques for In Vitro High-Density Microelectrode Array Systems

Impedance Spectroscopy and Electrophysiological Imaging of Cells With a High-Density CMOS Microelectrode Array System

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