New multifunctional CMOS microelectrode array presented at ISSCC 2016 – Bio Engineering Laboratory

Feb 06, 2016 04:56 PM  online, opensource.

this is the array that Andreas showed us in his talk on feb 5.

he presented this at  ISSCC 2016 in SF a few days ago.

it has abt 60,000 trodes.  trode array is 4.5 mm by 2.5 mm  and has 59,760 trodes

at a ptich of 13.5 microns  (5487 per mm2)

it has  2048  AP readout channels;  32 LFP readouts; and 28 neruoxmtr units.

SM appraoch = switch matrix... want to delvier every system function to any arbitrary trode or seet.

each trode is  3 by 7. 5microns...  each AP channle   5 stages.

fab in  180 nm CMOS.

paper is also here and is online  (one page);

1st author is  Viajy Viswam.  PI = A Hierlemann.

array has  5487 trodes per mm2 in a 4.48 by 2.43 mm array.

it has  2048  AP = action potential readout channels.  summary follows.

. This monolithic system incorporates a large high-density electrode array of 4.48×2.43mm2 including 59,760 electrodes at a 13.5μm pitch (5487 electrodes/mm2 ) to record from large preparations/networks at subcellular resolution and the following circuitry units: 2048 action-potential (AP, bandwidth: 300Hz to 6kHz) readout channels, 32 local-field-potential (LFP, bandwidth: 1Hz to 300Hz) readout channels, 32 current recording units, 32 impedance units, 16 dual-mode voltage/current stimulation units, and 28 neurotransmitter measurement units.

The system architecture critically relies on the SM approach [5], as we want to deliver every system function to any arbitrarily selectable electrode/electrode sets to perform, at the same time, stimulation and measurements of various cell or network parameters in parallel. Each electrode (Pt, 3×7.5μm2 ) is included in a 13.5×13.5μm2 pixel, along with 4 switches and 3 SRAM cells for switch control. Neuronal signal lines are all shielded with analog supply/ground tracks to minimize crosstalk. In addition to the higher electrode density, the largest high-density block here consists of 45x45 electrodes (Fig. 22.8.3), which is 4-times that in [5], due to technology scaling (0.18μm CMOS) and more metal layers. Array reconfiguration takes up to 4.5ms..

Shown in Fig. 22.8.1, 16 stimulation buffers allow for simultaneous stimulation of multiple cells on different electrodes in current and voltage mode.  By disconnecting the current conveyor (CCII) from the electrode upon reaching a pre-set value, accidental electrolysis and cell damage are avoided.

Artifact removal is achieved by storing the electrode resting potential on a capacitor before stimulation and by re-applying that potential after stimulation.

Both, AP and LFP signal readout was implemented and optimized for distinct characteristics of the two types of signals without increasing overall readout unit complexity. However, we here focus on the AP recording channels due to space limitations. Each AP channel consists of four fully-differential stages. The total gain can be programmed in steps of 3dB from 29dB to 77dB.

Dissociated cortical cells of embryonic-day-18 Wistar rats were cultured over 3-to-4 weeks on the chip

We demonstrate a multifunctional monolithic MEA system (Fig. 22.8.7) featuring the largest high-density (13.5μm pitch) electrode array to date, in which every electrode can be connected to various functional circuitry units. Its main specifications are compared with prior works in Fig. 22.8.6. Up to 2048 electrodes can be simultaneously used for recording at noise levels as low as 3.2μV and meanwhile, stimulation, impedance measurements can be performed to detect cell positions/morphologies, or neurotransmitter release can be measured. This system is an enabling tool for in-depth neuroscientific studies targeting subcellular–resolution details or large complex networks.

New multifunctional CMOS microelectrode array presented at ISSCC 2016 – Bio Engineering Laboratory

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