The most sensitive microelectrode array system for in vitro extracellular electrophysiology.

MED64

Simultaneous recording of extracellular signals across 64 channels without pulling glass electrodes

  • Signals (evoked potentials or spontaneous activity) are acquired with 64 planar microelectrodes patterned on the MED probe.
  • Any of the 64 electrodes can be used for stimulation (up to two simultaneously). Stimulus channels and waveforms are selectable by software.

Advantages

Reveal important extracellular signals that can be hidden by other systems!

The MED64 features with the industry’s lowest-impedance planar microelectrodes (10 kohm at 1 kHz), that afford several unique benefits…

The most sensitive (The best signal-to-noise ratio)

Electrode impedance is a major factor in determining an electrophysiological acquisition system’s baseline noise level. Lower electrode impedance results in lower baseline noise level. When using MEAs, having a low baseline noise is the only method to achieve a good signal-to-noise ratio because electrodes do not penetrate into biological samples.

Thanks to the industry’s lowest-impedance electrodes, the MED64 can provide the lowest baseline noise level which can reveal important signals that may be hidden by other systems.

RMS Noise Comparison

Baseline noise and spike extractions

Recording inside of a humidified incubator

A general rule for electrophysiology system is “The head amplifier needs to be placed close to electrodes”. However, MED64’s low-impedance electrodes do not even require this configuration. The MED Connector (holding the MEA) is connected to the amplifier via a 2 meter long cable, that does not generate signal attenuation.

Recording in incubator
Recording in incubator

 Recording from cultured neurons in an incubator

Excellent capabilities for stimulation

Stimulation using planar microelectrodes is more challenging than recording. One of the reasons is stimulated electrodes need some time to discharge. This phenomenon appears as “stimulus artifacts” that interfere with signals coming right after the stimulation.

The MED64’s low-impedance electrodes discharge instantly, so the stimulus artifacts return to 0 within 0.5 msec. Evoked signals can be clearly measured immediately after stimulation. MED64’s excellent stimulation capabilities are validated by hundreds of publications.

Recording of evoked signal that comes right after stimulus artifact (left). Example for dragged stimulus artifacts (right).

A rate limiter for stimulating with MEAs is that voltage charged to planar electrodes must not go beyond 1V to avoid electrolysis. This could hamper the amplitude of the current that can be delivered through an MEA.

The MED64’s planar microelectrode has much higher capacitance (22,000 pF for 50 μm electrode) relative to other commercially available MEA, enabling large current-driven stimulation (up to 200 μA) to all electrodes of the MED64.

Stimulation

Differences in behavior in response to stimulation for electrodes of different material composition

What is the reason for the low-impedance?

Making planar microelectrodes for MEA is difficult. MEA electrodes need to have large surface area to achieve low-impedance (Electrode impedance is inversely proposed to its surface area).

This dilemma can be solved by making electrode surface rough on the nano level. The planar microelectrode of the MED Probe is coated with platinum black using a unique technology that Panasonic/Alpha MED established. This manufacturing method dramatically increases the electrode surface area 100-200x larger and its impedance decreases accordingly.

Microelectrode
Electrode Surface

Electrode structure in the MED Probe (left) and close-up view of a platinum black electrode (right).

Electrode Impedance

Comparison of electrode impedance (MED64 electrode vs flat-surface (ITO) electrodes).

MED64 Basic

MED64 Basic

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MED64 Basic >>

MED64 Quad II

MED64 Quad II

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MED64 Quad II >>

MED64 Allegro

MED64 Allegro

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MED64 Allegro >>

MED64 Plex 4/8

MED64 Plex4-8

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MED64 Plex 4/8 >>

MED64 Presto

MED64 Presto

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MED Presto >>

MED64 Amplifier

MED64 Amplifier

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MED64 Amplifier >>

MED64 Connector

Connector

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MED64 Connector >>

MED Probes

MED Probe

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MED64 Probe (MEA) >>

MED64 Mobius Software

MED64 Mobius Software

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MED64 Mobius Software >>

MED64 Perfusion

MED64 Perfusion

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MED64 Perfusion >>

MED Accessories

MED-C06

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MED64 Accessories >>

References – MED64