Alpha MED Scientific MED64-Entry User manual

MED64-Entry Manual

i
Table of Contents
1. Introduction ……………….. 1
2. Configuration of the MED64-Entry ……………….. 1
2.1. Part names and functions ……………….. 2
2.1.1. MED64-Entry Amplifier ……………….. 2
2.1.2. Accessories of the MED64-Entry Amplifier ……………….. 2
3. Setup of the MED64-Entry ……………….. 3
3.1. Connection of the data acquisition device to the PC ……………….. 3
3.2. Considerations for the position of devices ……………….. 4
3.3. Power source ……………….. 4
3.4. Connection to the MED64-Entry Amplifier ……………….. 5
3.4.1. Part names and functions of the MED Connector ……………….. 5
3.4.2. Connections of the MED Connector and the data acquisition device ……………….. 5
3.4.3. Positioning of the terminal of the MED Connector ……………….. 6
3.4.4. Electric shield with aluminum foil ……………….. 7
3.4.5. Preparation for the noise check -attaching the MED Probe ……………….. 7
3.4.6. Noise check ……………….. 8
3.4.7. Maintenance of the MED Connector ……………….. 8
4. Data acquisition by the control software “MED16” ……………….. 9
4.1. Setting the data acquisition schedule - RECORD subpanel ……………….. 10
4.2. Creating the stimulation pattern - STIMULATION subpanel and STIMULATION PATTERN tabs ……………….. 11
4.3. Set data file output - FILE OUTPUT subpanel ……………….. 13
4.4. SIGNAL WAVEFORM panel ……………….. 14
4.5. BASELINE STABILITY panel ……………….. 14
4.6. Replaying data file output - function of REPLAY mode ……………….. 16
5. Abnormal noise ……………….. 17
5.1. Noise check point ……………….. 17
5.2. Noise relation to installation ……………….. 17
5.3. Noise relating to perfusion ……………….. 19
5.4. Identification of cause when a malfunction of the device is suspected ……………….. 20
6. Appendix ……………….. 21
6.1. Specification ……………….. 21
6.1.1. MED64-Entry Amplifier [MED-A16HM1] ……………….. 21
6.1.3. MED Connector [MED-C03] and MED Thermo Connector [MED-CP04] ……………….. 22
6.1.6 Data Acquisition PC System ……………….. 22
6.2. Explanation of the technology ……………….. 23
6.2.1. Signal acquisition by the MED64 System ……………….. 23
6.2.2. Electric stimulation by the MED64 System - Applying current to the micro electrode array ……………….. 24
6.2.3. Stimulus artifact and biphasic stimulation ……………….. 24
6.2.4. Stimulus current value and electrolysis ……………….. 25
6.2.5. About the stimulus interval ……………….. 26

1
1. Introduction
◆ The MED64 system is a micro electrode array (MEA) system commercialized for the first time in the world in 1997. Since then,
the MEA system has been widely used in the United States and the EU for basic research in the fields of the central nervous
system and the cardiovascular system. Nowadays, its application to screening for drug discovery is rapidly spreading, thanks to
its highly evaluated excellent operability and efficiency.
◆ The system use a MEA with 64 planar electrodes arrayed in a pattern (MED probe) on a glass substrate. Users can acquire
extracellular potential simply by placing a tissue slice or by culturing cells on these electrodes. Current stimulation can be
applied through any electrode selected by software. Unlike a glass capillary electrode, the MED64 system requires no
troublesome operations to measure spontaneous activity or evoked response and no special training for electrophysiological
experiment is necessary. The system allows for accurate and easy measurements even by unexperienced researchers.
◆ The electrodes are made of platinum black or carbon nanotube with impedance 7 to 10 kΩ, the lowest impedance among
similar products on the market. The system is substantially free from external noise, thanks to its low impedance electrodes. It
needs no special environment/facility for electrophysiological experiment, such as a shield box, and it can be placed on a
laboratory desk for stable, daily measurement with no need for noise elimination.
◆ The MED64-Entry detects and amplifies extracellular potential using 16 out of 64 MEAs of the MED probe. The control software
“MED16” is specifically designed for data acquisition and after an experiment, the data obtained can be analyzed in various ways
by using the MED64 Offline toolkit.
2. Configuration of the MED64-Entry
The MED64-Entry Amplifier has a 68-pin SCSI cable terminal that can be connected to a MED Connector (MED-C03) or MED Thermo
Connector (MED-CP04). The amplifier has a channel selector circuit inside and acquires signals from 16 out of 64 electrodes of the
MED Probe in accordance with 1 of 3 patterns shown below (the pattern is defined at shipping).
MED64-Entry Amplifier
Data acquisition PC
Control software
“MED16”
MED Probe
MED Thermo
Connector
Headstage for MEA
Data acquisition
device (PCIe type)
MED Probe
MED Connector
OR
Multifunction
cable
68-pin SCSI cable

2
Type A Type B Type C
The extracellular potential detected at the recording electrodes of the MED probe is amplified 100 times by the MED64-Entry
amplifier and converted from an analog to a digital signal by a data acquisition device (National Instruments Corporation) with a
built-in PC. The signal acquisition and the application of the stimulation current is controlled by dedicated control software.
2.1. Part names and functions
2.1.1. MED64-Entry Amplifier
【Front】 【Back】
➊POWER ….. To switch ON/OFF of the power.
➋INPUT ….. An analog input terminal to input signals from the MED connector. It is connected to a connector terminal via the 68-
pin SCSI cable.
➌SIGNAL GND ….. A ground terminal to connect a lead for grounding.
➍PCIe-6343 ….. Output terminals to the data acquisition device (PCIe-6343, National Instruments Corporation). They are
connected to a VDHCI terminals of the data acquisition device on the back of the data acquisition PC via
multifunction cables (192061C-02, National Instruments Corporation). (0) is the output terminal for ch 1-8 (top
VDHCI terminal) and (1) is the output terminal for ch 9-16 (bottom VDHCI terminal).
➎DC INPUT ….. To connect to a power adaptor cord.
2.1.2. Accessories of the MED64-Entry Amplifier
➊ Power adaptor ➋ Data acquisition device (in the Desktop PC) ❸ Multifunction cable (1 m) x 2
2.1.3. Data Acquisition PC System
➊Desktop PC ➋Display monitor
❶
❷
➌
❹
❺
❹

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3. Setup of the MED64-Entry
Thanks to the excellent electrode impedance (impedance of 50 µm electrode is 10 kΩ in frequency range 1 kHz) of the MED Probe,
which is the sensor of the MED64-Entry, the MED64-Entry offers several technological advantages:
1) Less influence by external noise (hum noise, etc.)
2) Very low Johnson noise (baseline noise) at about several µV
3) The MED Probe/Connector can be installed at a place physically distant from the amplifier (e.g., inside of an incubator with
100% humidity) via a 2 m connection cable, without being affected by noise or attenuation of the signal acquired.
A faraday cage or vibration isolation table that is typically necessary for an electrophysiological experiment is not necessary for the
MED64-Entry, but the MED64-Entry should be set up on a stable table without vibrations, such as a laboratory desk. A desk of about
100 cm width and 75 cm depth is necessary. For the user’s convenience, a larger desk is preferable. The power adaptor connected to
the amplifier, etc., serves as a magnetic field-derived noise source. When the MED64-Entry is set up on a desk against a wall, make
space for the cord between the wall and the desk and place the adaptor on the floor in order to place the power adaptor at a
distance from the amplifier and other components (the desk must not be fixed to the wall). Alternatively, a space is necessary to
ensure sufficient distance between the MED64-Entry and the power adaptor.
3.1. Connection of the data acquisition device to the PC
Note: For the MED64-Entry marketed in Japan, the process explained in this section is completed before shipment.
Open the housing of the PC, remove the extension slot cover on the back, and attach and fix with a screw the PCIe-6343 to the PCI
Express x1 slot on the mother board.
Run the NI-DAQ mx installer (ver. 16.0 or later) on the accessory DVD of PCIe-6343 to install NI MAX to the PC and connect the
MED64-Entry amplifier to the PC using a multifunction cable.
Launch NI MAX to confirm the configuration of the device. If a data acquisition device other than the PCIe-6343 was previously
connected to the PC, assign the name “Dev1” only to PCIe-6343 and assign other names to any other devices (on the control
software, “Dev1” is used as the identification code of PCIe-6343).
Expansion slot
cover
PCI Express x1
slot

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3.2. Considerations for the position of devices
In order to ensure sufficient space for an experiment, place the PC on the MED64-Entry amplifier (not essential). Pay attention so
as not to damage the housing of the MED64-Entry Amplifier with the legs of the PC. Place the display monitor next to the PC and
the MED Connector in front of the monitor. Do not place the power adaptor or other electronic devices close to the connection
terminal on the back of the amplifier.
Above is an image of the ideal positions of components. The user can perform an experiment smoothly when there
is a sufficient space next to or at the back of the laboratory desk with a power strip on the floor. If no perfusion
system is used, about 100 cm width is sufficient, otherwise a larger space is necessary.
3.3. Power source
Three power sources are necessary for the MED64-Entry Amplifier and the Data Acquisition PC System (the desktop PC and the
display monitor), and one additional power source is necessary to use the MED Thermo connector when it is used. Connect all the
cords to one power strip connected to a wall outlet with the ground terminal (do not use an outlet on the desktop rack because it
is often not grounded properly). Do not connect devices that are not necessary for the MED64-Entry to the power strip or to the
wall outlet to which the MED64-Entry and other components are connected. Place the power cable and the power adaptor at a
distance from the amplifier, the MED Connector and the 68-pin SCSI cable.
Display monitor
PC
MED64-Entry
Amplifier
Space for cables on the back of the amplifier
About 20 cm depth is necessary.
MED Connector
Mouse
Keyboard
PC
Display monitor
Power strip (on the floor)
Power adaptor (on the floor)
75 cm
120 cm
アンプ後面
Data acquisition device other
than PCIe-6343 (not connected).
Save after assignment
of the name.
Space for cables in front of the amplifier
About 15 cm depth is necessary.
Pump (when
perfusing)
Water bath
(when perfusing)
MED64-Entry Amplifier

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3.4. Connection to the MED64-Entry Amplifier
3.4.1. Part names and functions of the MED Connector
【Top unit】 【Base plate】 【Accessory】
➊Output terminal ….. To connect to INPUT of the MED64-Entry Amplifier via the accessory, the 68-pin SCSI cable.
❷Fixation screw ….. To fix the fitted top unit and the base plate with a MED Probe attached.
❸Contact pin ….. To contact with the MED Probe terminal to read signals.
❹Ground wire with an bagworm clip ….. To connect to a platinum wire with a perfusion cap when a perfusion system is used.
❺68-pin SCSI cable (2 m) ….. A conductive cloth tape and ground wire are wounded on the cable.
3.4.2. Connections of the MED Connector and the data acquisition device
➊Connect the output terminal of the MED Connector and the INPUT terminal of the MED64-Entry Amplifier, using the 68-pin
SCSI cable.
➋Connect the lead of the 68-pin SCSI cable to the SIGNAL GND terminal of the MED64-Entry Amplifier.
Note1: The 68-pin SCSI cable is wound with a conductive cloth tape and an uncoated lead is wound on it. If the other side of the
lead is free, the conductive cloth tape may serve as an antenna that collects electric noise and may cause noise. Make sure
that the other side of the lead is connected to the SIGNAL GND terminal of the MED64-Entry Amplifier (to use the
conductive cloth tape as an electric shield).
Note2: In order to prevent noise, use the SIGNAL GND terminal of the MED64-Entry Amplifier for single-point grounding when
the peripheral devices are grounded.
Loosen the screw of the SIGNAL GND terminal, insert the ground wire into the hole (left panel), and fix with a screw (right panel).
➌Connect the PCIe-6463 (1) terminal of the MED64-Entry Amplifier to the PCIe terminal (bottom) on the back of the PC, using
the function cable.
❶
❹
❶
❷
❸
❹
❺
❺
❷
❷
❸

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➍Connect the PCIe-6463 (0) terminal of the MED64-Entry Amplifier to the PCIe terminal (top) on the back of the PC, using the
function cable.
➎Connect the power adaptor to the MED64-Entry Amplifier.
3.4.3. Positioning of the terminal of the MED Connector
Place the MED Connector with its output terminal and the 68 pin SCSI cable on the right side. In this position, the left top of the
MED Probe is assigned to ch 1 and the right bottom is assigned to ch 64. The orientation of the MED Probe is important because
the electrode number of the MED Probe is defined by the contact pins of the MED Connector.
Correspondence between the contact pin of the MED Connector and the electrode number: correspondence from the contact surface side with
the output terminal on the right (left panel) and correspondence with the MED probe terminal (right panel). R indicates the reference electrode.
Correspondence between the MED Connector output terminal and the electrode number. R indicates the reference electrode.
ch 1
ch 64
ch 56
ch 8
R1
R2
R3
R4
ch 1
ch 64
ch 56
ch 8
(0)
(1)
(0)
(1)

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3.4.4. Electric shield with aluminum foil
If a noise check reveals that external electric noise is affecting the MED Connector, the noise may be avoided by placing a sheet of
aluminum foil under the MED Connector and using a lead to connect the aluminum foil sheet and the SIGNAL GND terminal of
the MED64-Entry Amplifier for grounding.
A sheet of aluminum foil serves as an electric shield by grounding. Magnetic field-derived noise cannot be prevented by an electric shield.
Note: Although the MED Connector is made from aluminum, its surface is coated and insulated from the aluminum foil. Make
sure that the aluminum foil is grounded to the SIGNAL GND terminal of the MED64-Entry Amplifier when a sheet of
aluminum foil is placed under the MED Connector, even if the baseline noise level is within an acceptable range. Without
grounding, the aluminum foil serves as an antenna to collect electric noise and may generate unexpected noise.
MED64-Entry after setup. In this example, the PC is placed on the right side.
3.4.5. Preparation for the noise check – attaching the MED Probe
Loosen the fixation screw of the MED Connector to remove the top unit.
On the base plate, place the MED Probe filled with saline, such as aCSF or PBS holding the ring chamber of the MED probe or the
end of the glass substrate. Pay attention so as not to touch the terminals. If any waterdrop, medium or smudge is on the terminal,
wipe the terminal with a Kim wipe before setting the MED Probe. Subsequently, place the top unit on the MED Probe and fix with
a fixation screw.
Fixation
screw
Top unit
Base plate
Fixation
screw

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Note1: Loosen/tighten both screws little by little at the same time. When the screws are sufficiently loosened/tightened, they can
be completely loosened/tightened one by one. If only one screw is completely tightened/loosened without
tightening/loosening the other screw, the second screw cannot be inserted perpendicular to the hole.
Note2: Do not touch the contact pin of the MED Connector with bare hands. If sebum of the hand attaches to the pin, contact
impedance between the contact pin and the terminal of the MED Probe will increase and may cause noise. Pay attention
so as not to spill liquid (saline, medium etc.) on the MED Probe after it is set. Prevent liquids from coming into contact
with the contact pin.
3.4.6. Noise check
Double-click the MED16 icon on the desktop to launch the control software “MED16”. Select Spontaneous from EASY SETTINGS
and click the replay button.
Data acquisition will start 5 seconds later and the baseline noise will be displayed. The ideal baseline noise level is about ±8 µV
peak-to-peak. When baseline noise shows a normal pattern, the setup ends. For the details of operating the MED16 refer to p. 9
“Data acquisition by the control software” Refer to the relevant application note for the preparation of specimens used for the
experiment.
Normal baseline noise.
3.4.7. Maintenance of the MED Connector
A printed circuit board onto which 68 contact pins contacting the terminal of the MED probe are soldered is fixed by screws to
the top unit of the MED Connector. Spring-loaded pins are used as contact pins and keeping the surface of the pins clean is
important for the maintenance of the MED Connector. If any abnormal noise is found at a particular electrode and noise persists
on that electrode even when the orientation of the MED Probe is changed, the noise may be caused by deformation (crushing)
due to the wear of the contact pins associated with everyday use or dust or sebum on the contact pins. In the latter case, the
noise may be reduced by wiping the contact pin by pushing the eyeglass cleaner cloth on the pin. Do not use ethanol because
the contact pin is filled with lubricant for the spring. The printed circuit board needs to be replaced (paid repair) in the case of
malfunction due to wear of the contact pin associated with everyday use or malfunction due to salt (perfusion solution or media)
attached on the pin.