Multichannel Systems MPA32I User Manual

32-Channel Miniature Preamplifier

Manual

Information in this document is subject to change without notice.

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© 2014 Multi Channel Systems MCS GmbH. All rights reserved.

Printed: 11. 02. 2014

Multi Channel Systems

MCS GmbH

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72770 Reutlingen

Germany

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www.multichannelsystems.com

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Table of Contents



1 Important Information and Instruction 1

1.1 Operator's Obligations 1

1.2 Guarantee and Liability 1

1.3 Important Safety Advice 2

2 Welcome to the MPA32I 3

3 Setting Up and Connecting the MPA 4

3.1 General Setup Recommendations 4

3.2 Testing the Noise Level of the Setup 5

4 Setting up MC_Rack 6

5 Connecting FlexMEAs 8

5.1 EcoFlexMEAs 10

5.1.1 Connecting 32-Channel NeuroNexus Probes 11

5.1.2 Adapter-NN-32 Pin Layout 12

5.2 Connecting 54-Channel NeuroNexus Probes 13

6 Service and Maintenance 15

7 Pin Layout 16

7.1 Power Supply 16

7.2 Test Model Probe 17

8 Contact Information 18

9 Technical Specifications MPA32I 19

10 Datasheet 20

Important Information and Instruction

1 Important Information and Instruction

1.1 Operator's Obligations

The operator is obliged to allow only persons to work on the device, who

 are familiar with the safety at work and accident prevention regulations and have been

instructed how to use the device;

 are professionally qualified or have specialist knowledge and training and have received

instruction in the use of the device;

 have read and understood the chapter on safety and the warning instructions in this manual

and confirmed this with their signature.

It must be monitored at regular intervals that the operating personnel are working safely.

Personnel still undergoing training may only work on the device under the supervision
of an experienced person.

1.2 Guarantee and Liability

The General conditions of sale and delivery of Multi Channel Systems MCS GmbH always apply.
The operator will receive these no later than on conclusion of the contract.

Multi Channel Systems MCS GmbH makes no Guarantee as to the accuracy of any and all tests
and data generated by the use of the device or the software. It is up to the user to use good
laboratory practice to establish the validity of his findings.

Guarantee and liability claims in the event of injury or material damage are excluded when they
are the result of one of the following.

 Improper use of the device.

 Improper installation, commissioning, operation or maintenance of the device.

 Operating the device when the safety and protective devices are defective and/or inoperable.

 Non-observance of the instructions in the manual with regard to transport, storage, installation,

commissioning, operation or maintenance of the device.

 Unauthorized structural alterations to the device.

 Unauthorized modifications to the system settings.

 Inadequate monitoring of device components subject to wear.

 Improperly executed and unauthorized repairs.

 Unauthorized opening of the device or its components.

 Catastrophic events due to the effect of foreign bodies or acts of God.

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32-Channel Miniature Preamplifier Manual

1.3 Important Safety Advice

Warning: Make sure to read the following advices prior to install or to use the device and the
software. If you do not fulfill all requirements stated below, this may lead to malfunctions or
breakage of connected hardware, or even fatal injuries.

Warning: Obey always the rules of local regulations and laws. Only qualified personnel should
be allowed to perform laboratory work. Work according to good laboratory practice to obtain
best results and to minimize risks.

The product has been built to the state of the art and in accordance with recognized safety
engineering rules. The device may only

 be used for its intended purpose;

 be used when in a perfect condition.

 Improper use could lead to serious, even fatal injuries to the user or third parties and damage

to the device itself or other material damage.

Warning: The device and the software are not intended for medical uses and must not be used
on humans.

 Malfunctions which could impair safety should be rectified immediately.

 Any physical damage of the cable, such as a broken cable, causes a physical damage of the

miniature preamplifier that cannot be repaired.

 Protect the device from heat. Do not autoclave!

 You can clean the connectors with distilled water in an ultra sonic bath, but keep the cable away

from the fluid. Dry the device with compressed air.

 Use and keep the device always in a dry environment. Do not expose it to fluids or vapor for

a longer period of time.

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2 Welcome to the MPA32I

The 32-Channel Miniature Preamplifier MPA32I is connected to the microelectrodes for providing
the initial tenfold amplification stage.

FlexMEAs

It has additional common ground and reference electrode inputs. The reference electrode
is ideally identical to the recording electrodes and placed into a comparable but inactive area or
tissue. Background or noise signals that are picked up by both the reference electrode and the
recording electrodes are removed.

The metal case provides electrical shielding. Electrode damage is prevented by the very
low bias current. The high input impedance ensures stable long-term recordings:
Ideally, the input impedance would be infinite. As low voltages are generally recorded, a high
current would flow if the input impedance were low. As a result, the amplifier would not be able
to deliver the current, and the voltage would break down. The miniature preamplifier has a high
input impedance to avoid this problem.

Adapters for all standard microelectrodes such as NeuroNexus probes (from
www.neuronexustech.com) for acute and chronic implantations ensure a close proximity to the
probe to minimize signal loss and cross talk. Adapters are not included in the standard scope of
delivery and have to be ordered separately. For custom adapters, please ask your local retailer or
contact Multi Channel Systems.

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32-Channel Miniature Preamplifier Manual

3 Setting Up and Connecting the MPA

3.1 General Setup Recommendations

In the following, you find general recommendations for the installation.

Important: It is important that the complete setup refers to a single common ground. The
reference input has always to be connected. It is recommended to use a reference electrode.
However, if you are not using a reference electrode, connect the reference input to ground
(GND). Otherwise, noise picked up by the reference input will be subtracted from the recording
signals. This will either lead to signal loss or to a very high noise level.

1. Ground the animal with a ground electrode of large surface area, for example, a liquid gel

adhesive electrode, that is connected to the ground of the setup, for example, a large metal
table or a Faraday cage, to avoid pickup of noise from the environment. The ground electrode

is best positioned in an electrically inactive region (not near muscle, nor heart), for example, at
the belly.

2. Connect the GND input or the metal case of the miniature preamplifier to the common
ground of the setup. (The GND input is internally connected to the metal case.)

3. Connect the reference electrode to the reference input of the miniature preamplifier.
Generally, a reference electrode is inserted into non-active tissue of the experimental model.
The reference electrode should be identical to the recording electrode so that both electrodes
see the same background noise. This is necessary because despite the grounding, the animal’s
body often has not exactly a potential of zero, due to the electrode impedance, for example.
The background noise is then subtracted from the recording signal, increasing the signal to
noise ratio. Please note that this may not work if the complete setup is not properly grounded.

4. (Optional) If two reference electrodes are used, connect the second electrode to the free
reference input. Otherwise, leave it free. It is generally not necessary to use a second reference
electrode. It can be used to enlarge the surface area of the reference, though.

5. Connect the recording electrodes to the recording channels of the miniature preamplifier.
You can either use single electrodes or multitrodes with the miniature preamplifier. MCS provides
adapters for standard probes.

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6. Connect all unused recording channels to the GND input or to the reference electrode if the
reference and ground electrode of the amplifier are short circuited, to avoid noise pickup. As the
total amplifier gain generally lies in the range of 1000, even very small noise signals may generate
high noise signals.

7. If you are not using a Faraday cage, it might be necessary to shield the complete setup with
aluminum foil or similar to prevent electrical interference from the outside. Connect the
aluminum foil to the ground of the setup (for example, the metal table).

Troubleshooting: If you observe problems with noise, check that the ground of the setup
is connected to exactly the same ground as the data acquisition computer. For example,
connect the metal table to the ground / earth wire of a free power outlet (of the same electrical
system), as the computer is generally connected to ground/earth via the power plug, too.
Also, connect the data acquisition computer’s metal case with a thick ground wire
to the ground of the setup (for example, the metal table), preferably with a 4 mm plug.

3.2 Testing the Noise Level of the Setup

FlexMEAs

A terminal plug that connects all inputs to ground, and a test model probe that mimics the
electrode impedance are provided for testing the noise level of the setup. Please note that all

instruments were thoroughly tested at the factory site before delivery. The suggested tests are
mainly intended for optimizing and troubleshooting your setup, to exclude any damage that
might have occurred during transportation, or to fulfill your own guidelines, for instance. It will
take only a few minutes time and can save time and trouble in the long run. Multi Channel
Systems recommends running these tests before you start your real experiments.

1. Connect the terminal plug to one miniature preamplifier and the test model probe to the other
as shown in the picture (do not mismatch the polarity). If you have only one MPA32I, you can
perform the two tests consecutively.

2. Connect the MPA32I with the test model probe to channels 1 to 32 of the signal collector.

3. Connect the MPA32I with terminal plug to channels 33 to 64 of the signal collector.

4. Make sure that all other connections are appropriate, and that your setup has an appropriate
grounding and shielding as recommended in the chapter “General Setup Recommendations”.

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32-Channel Miniature Preamplifier Manual

4 Setting up MC_Rack

Please refer to the MC_Rack Manual for more information.

 Start MC_Rack.

 Open the file MPA32I_NoiseTest.rck on the installation volume (see folder Tutorial).This rack

contains the virtual MC_Card instrument as data acquisition device with a continuous raw data
display and an Analyzer to measure the peak-to-peak amplitude.

 Click Start to start the recording.

 — OR — Set up the rack on your own:

 Click Data Source Setup on the Edit menu. Select a 1-dimensional layout. Select the number

of electrode channels (at least 32).

 Add the data acquisition to your virtual rack.

 In the tree view pane of the virtual rack, select the data acquisition, and click the Hardware

tab. Enter the total amplifier gain according to the specifications of the instruments. For example,
for a miniature preamplifier with a gain of 10 and a following filter amplifier with a gain of 100,
the total gain is 1000.

 Select an input voltage range of –819.2 to +818,8 mV and a sampling rate of 10000 Hz.

 On the Edit menu, click Add Data Display to add a raw data display to your virtual rack.

 In the virtual rack tree view pane, select the Display 1 and click the Layout tabbed page.

Set up a channel map with channels 1 to 64.

 Adjust the display ranges to 500 ms and +/–50 μV.

 On the Edit menu, click

typical channels on the Channels tabbed page. Select the Peak-Peak Amplitude parameter on
the Analyzer tabbed page.

 On the Edit menu, click Add Parameter Display to add a Parameter Display to the virtual

rack.

 In the virtual rack tree view, select the Display 2 and click the Layout tabbed page. Set up

a channel map with all channels that were assigned to the Analyzer.

Add Analyzer to add an Analyzer to the virtual rack. Select all or two

 Click the Ranges tabbed page and enter 0 to 10 s for the x- range and 0 to100 μV for the

y- range.

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