MZ60 MicroElectrode Array Interface

MZ60 MicroElectrode Array Interface
9-3
MZ60MicroElectrodeArrayInterface
MZ60 Overview
The MZ60 Microelectrode Array
(MEA) Interface is used with our
RZ2 BioAmp Processor and the PZ5
NeuroDigitizer (or PZ2 Amplifier) as
part of a complete solution for high
spatio-temporal resolution tissue slice
and cell culture recordings.
The interface supports simultaneous
stimulation and extracellular in-vitro
recording on up to 60 channels.
Headstage buffering on the MZ60
provides high signal-to-noise ratio,
sensitivity, and stability for long
experimental durations.
The MZ60 is compatible with a large selection of MEA plates and both inverted and
upright microscopes.
The MEA System A typical system consists of an RZ2 processor, a PZ5 digitizer and the MZ60 MEA
interface. An optional stimulus generation device may also be used and controlled by
the RZ2 processor as part of an integrated solution. The diagram below illustrates
the function of the components in the system.
MEASystemDiagram
The MZ60 acquires analog input signals from cell lines or tissue slices via an MEA
plate and sends those signals to the PZ5 digitizer. All channels are digitized on the
PZ5 at up to ~50kHz sampling rate per channel. Digitized data is streamed to the
RZ2 multiprocessor DSPs on a fiber optic connection and processed data is
MZ60 MicroElectrode Array Interface
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System 3
transferred to the PC for data storage. A PZ2 amplifier may be substituted for the
PZ5 in some cases. A single RZ2 and PZ5 system is capable of interfacing with up
to two MZ60’s.
Stimulation can be delivered to any of the MZ60's electrode sites while the RZ2
processor simultaneously records from non-stimulus channels and may be provided by
the RZ2 processor or an optional stimulus device.
The MEA Interface
The MZ60 is compatible with the standard 49 x 49 mm arrays from NMI or Ayanda
Biosystems and can accommodate a wide selection of readily available arrays. The
arrays are placed on an aluminum plate and spring loaded connections are secured
over the contact pads when the top is lowered and locked using the twist lock
mechanism.
A voltage-follower headstage provides a high input impedance and low output
impedance with unity-gain. The dynamic range of the MZ60 and PZ5 is 500 mV
with a signal resolution of 3 μVolt or less at ~25kHz sampling rate.
The MZ60 channels are organized in four individual 16-channel banks that
correspond to banks of channels on the PZ5 digitizer. Each bank transmits 15 analog
signals recorded from the MEA to the PZ5 digitizer (the sixteenth channel of each
bank is connected to ground and is not used). If any channel is designated for
stimulation, it is grounded internally on the PZ5.
Voltage Range
The voltage input range of the PZ5 digitizer is lower than the MZ60 and must be
considered the effective range of the system. If using another preamplifier,
check the specifications for voltage range. Also keep in mind that the range of
the MZ60 varies depending on the power supply provided by the digitizer or
preamplifier. the TDT digitizer and preamplifiers supply +/- 1.5 V, but third party
preamplifiers may vary. TDT recommends using preamplifiers which deliver +/- 2.5
V or less. Check the preamplifier voltage input and power supply specifications and
headstage gain to determine the voltage range of the system.
Input range when using +/- 1.5 V
power source:
Input range when using +/- 2.5 V
power source:
+/- 0.9 V
+/- 1.9 V
Hardware Set‐up To insert the MEA into the MZ60:
1.
Twist the knob on the front edge of the MZ60 counterclockwise to release
the hinged top.
2. Lift the top and position the MEA on the aluminum plate.
3. Lower the top and twist the knob clockwise to secure the MEA inside the
interface housing.
Important!: The securing knob on the MEA turns on a screw that allows for
pressure adjustment between the MEA plate and the MZ60 interface contact
pins. The pressure should be set to achieve only light contact between the
spring loaded contact pins and the MEA plate (enough pressure to visually
depress the spring contacts). Excessive pressure may cause damage to the
device or MEA plate.
MZ60 MicroElectrode Array Interface
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Refer to the vendor’s specifications of the chosen MEA plate regarding the MEA
pinouts and technical specifications of the electrodes.
To connect the system hardware:
1.
Ensure that the TDT drivers, PC interface, and device chassis are installed,
setup, and configured according to the System 3 Installation Guide provided
with your system.
2. Connect the MZ60 Interface to the PZ5 digitizer via the MZ60 interface
cable provided. Attach the 68-pin D-Sub connector on the interface cable to
the corresponding connector on the MZ60.
3. Attach each of the labeled Mini-DB26 connectors to the corresponding
channel bank connector on the PZ5 digitizer.
4. Connect the PZ5 digitizer to the RZ2 processor using the provided fiber optic
cable. The fiber optic wires are keyed and color coded to reduce connection
errors.
5. Power on the RZ2 processor and PZ5 digitizer.
6. If using the system with other devices, such as a third party stimulus device
or preamplifiers, see the documentation for those devices for hardware
connection information.
SetupoftheMEASystem
MEA Interface Features
Analog Input and Output
The MZ60 supports MEAs containing up to 60 electrode sites. Any of these analog
channels may be configured for recording or stimulus presentation using top panel
stimulus switches.
Stimulus Switches
A DIP-style switch for each of the 60 analog input channels controls whether the
channel is in Stimulate mode (ON) or Record mode (OFF).
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System 3
MZ60SingleChannelCircuitDiagram
Each of the sixty channels can be configured in one of two states:
Record:
Channels in record mode are connected to a PZ5 digitizer input
channel when the corresponding DIP-switch is in the OFF
position.
Stimulate:
Channels in stimulate mode allow current to pass through the
electrode to ground when the corresponding DIP-switch is in the
ON position. Stimulating channels are not connected to the PZ5
and will not saturate the input to the PZ5 digitizer nor are they
connected to the REF line on the MZ60. A common ground pin
is available on the MEA Interface.
WARNING! Channels designated for recording are still connected to the
corresponding stim port located on the MZ60. To avoid damage to the MZ60
headstage, DO NOT attempt to present stimulus signals to channels configured for
record mode.
MZ60 Interface Cable Connector
An interface cable is provided to connect the MZ60 to the PZ5 digitizer. The cable
features four mini-DB26 connectors which connect to four banks on the back of the
PZ5.
Common Ground Pin
A single ground pin is attached to the MZ60 and serves as the common ground for
both stimulating and recording channels on the MZ60. The PZ5 digitizer ground and
reference pins for each bank are tied to this pin internally when the PZ5 and MZ60
are connected.
Some MEA plates have an internal reference pin integrated into dish. Please review
the MEA dish manufacturer specifications for proper grounding.
Troubleshooting
This section is provided to address common issues that may be encountered when
using the MZ60 MEA Interface. If you need assistance beyond the scope of this
guide, contact tech support at 1.386.462.9622 or support@tdt.com.
MZ60 MicroElectrode Array Interface
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General Tips
When recording signals make sure that the PZ5 digitizer is not connected to the
charger as this will induce mains interference in your recordings.
Make sure there are no power strips or AC power sources anywhere near the MZ60
setup. Power strips will induce mains interference into your recordings. Also minimize
electrical interference from other electrical devices (50-60 Hz and their harmonics).
We recommend that the MZ60 and PZ5 are approximately 1 meter from computers,
oscilloscopes, RZ and RX devices and other electronic equipment.
Make sure there is no liquid on the MEA plate contacts. Clean the contacts gently
with isopropyl alcohol to assure a clean connection.
Make sure the MZ60 knob is oriented in the correct position. If the MZ60 top is not
tight enough, open the MZ60 and ensure that the MEA plate is seated correctly in
the MZ60 housing. As you close the MZ60 top ensure that all of the gold pins are
touching the MEA electrode dish contacts.
Make sure that all of the spring-loaded contact pins are not stuck in a compressed
position. If a pin becomes stuck, use a pair of forceps or small pliers to gently pull
the pin out.
MZ60 Noise Floor is Too High
If 50-60 Hz hum (caused by mains voltage sources) is prevalent in your
recordings, make sure that the common ground wire is making contact with the liquid
in the MEA.
Noisy Single Electrode Channels
Large noise signals may be a sign of a bad electrode contact or pin. To test the
electrode contact, rotate the MEA plate and see if the noise follows the MZ60
channel or the electrode.
If the electrode contact is affected you may remedy the problem by cleaning the
MEA contact sites with a cotton swab and some pure alcohol (100%). If the
problem persists after cleaning the MEA electrode contacts, the contacts are damaged
beyond repair and the MEA plate must then be replaced.
MZ60 Technical Specifications
Stimulus Input Channels
Up to 60 (0.75 mm female input pin)
Analog Input Channels
Up to 60
Input Impedance
1014 Ohms
Gain
Unity
Compatible MEAs
Standard MEA Arrays 49 x 49 mm
MZ60 MicroElectrode Array Interface
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System 3
MEA Connector Pinouts
Stimulate/Record Switching Banks A DIP-switch bank is located on each of the four sides of the MZ60 and toggles
between stimulate or record modes for 15 electrode sites. Stimulating inputs accept
0.75 mm male pins.
Pinouts are shown looking into the connector and reflect the digitizer channels
assuming the MZ60 is used with a PZ5-64 in Local, None, or Shared reference
mode. For higher channel count channel numbers may be offset depending on the
MZ60-PZ5 connections.
Note:
Channels 16, 32, 48, and 64 are grounded on the digitizer.
MZ60 MicroElectrode Array Interface
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