4 Core Multielectrode

Transcription

4 Core Multielectrode
Tetrode
Quartz-Platinum/Tungsten Microelectrode
Product Information
Technical Data:
• Quartz-Platinum/Tungsten microelectrode with 4 metal cores
insulated from each other by quartz glass
• Outer shaft diameter: app. 100µm
• Pencil like tip shape
• Impedance: 500k? …1.2M? per site
• Core arrangement: concentric
• Very good and reproducible tetrode effect
• High biocompatibility and therefore well suited for chronic recordings
• Very good signal-to-noise ratio caused by unique manufacturing
technique
Thomas RECORDING GmbH – Giessen – GERMANY
Email: info@ThomasRecording.com
Thomas RECORDING GmbH 24.10.2006 Rev 1.0
Web: www.ThomasRecording.com
1.
Product description
The 4-cores-Quartz-Platinum/Tungsten Multifiber Electrode, called Tetrode, was first
developed by Thomas RECORDING in Germany. Thomas RECORDING is the first
company in the world, which was able to design a microelectrode with 4 independent
cores with a quartzglass insulation and a diameter of less than 100µm. The electrode
fiber has a shaft diameter of about 96µm (To draw a comparison: a human hair has a
diameter of about 70 to 80 µm). The tip of this electrode can be especially treated for
the special requirements of our customers. For example the tip can be pulled and
grinded.
This new Tetrode will provide the neuroscientist the opportunity for a more thorough
exploration of cellular and neural functions. The Thomas RECORDING tetrode
enhances the achievable resolution far beyond the results, that can be reached using
the best combination of electrodes and arrays available so far. The tetrode is available
in two versions. One is ready for use with our Eckhorn Microelectrode manipulators. The
other version is for use with any other kind of manipulators.
2.
Technical Data:
OD=app. 96 µm
C1 = app. 26 µm
C2 = app. 14 µm
C3 = app. 14 µm
C4 = app. 14 µm
Dimensions:
Outer diameter,
Core diameters,
Material:
Core material:
Insulation Material:
Tip treatment:
Grinded in an angle of about 15° to 17°
Pulled and grinded in an angle of about 15° to 17°
Platinum-Tungsten alloy (95% Pt, 5% T)
Quartz-glass (ε=3.75)
Impedance values: about 0.2 MΩ - 4 MΩ (depending on the recording area)
Core arrangement: Concentric with one center core
Connectors:
Gold connectors
4.
Dimensions
Figure 1: Scanning electron microscope photo of the tetrode tip
Figure 2: Dimensions of the tetrode tip:
D1=38µm, A = 15° => D2 = 19.32µm A = 16° => D2 = 18.14µm, A = 17° => D2 = 17.10µm
Figure 3: a) Scanning electron photo of the tetrode tip, b) cross section of the tetrode
5.
Tetrode raw data recorded in human brainstem
Figure 4: Clinical tetrode recordings made
in the basal ganglia of an anesthetised
dystonia patient. The left pictures show
some recording samples at different
positions along the tetrode trajectory
through the GP. The recordings were made
with a TREC tetrode loaded to the clinical
microdrive system “TREC SCANNER I”
(Recordings made by Dirk Hoehl, TREC, 2001 in
Heidelberg, GERMANY)
The shown tetrode signals have a very
good signal-to- noise ratio of app. 10:1 for
that recording contact that is located very
close to the signal source (trace #2 from top
in the left picture). The other three traces
show lower voltage amplitudes according to
the larger distance between the recording
sites and the signal source.
This picture shows an area where no
activity could be detected (quiet zone).
Figure 4: This figure shows the principle of tetrode sorting. In this example we can separate up to three
units (A, B and C) from the multi unit recording by comparing the patterns on the four traces.
(Recordings made by Dirk Hoehl, TREC, 2001 in Heidelberg, GERMANY)
6. Tetrode data analysis
In figure 5 one can see an example of tetrode data clusters. One can see that in this
example 4 cells could be separated from a multi unit recording made with TREC
tetrodes loaded to a 64 channel Eckhorn system.
Figure 5: 3 dimensional presentation of PCA based clusters. (Raw data were recorded with TREC
Tetrodes by Dr. Matthias Munk, MPI Frankfurt, GERMANY)
Tetrodes
MEF9514264C
for Manual Manipulators
1. Electrode Dimensions
The quartz-platinum/tungsten tetrode has a standard outer diameter of app. 100µm.
This thin fiber can be strengthened with a glass pipette or a stainless steel tube so
that it can be used with a standard manual microelectrode manipulator.
Figure 1: Dimensions of the tetrode
Glass Pipettes:
L1= 60mm or 80mm (other lengths on request)
D=1mm or 1,5mm
Metal Tubes:
L1=custom made
D=305µm (30 gauge) or 254µm (31 gauge)
How long should the fiber protrude out of the metal tube/pipette? Please specify L2!
Figure 2: Tetrode or Heptode fiber strengthened with a glass pipette
Figure 3: Tetrode or Heptode fiber strengthened with a stainless steel tube
2. Fiber Tip Shape
The quartz-platinum/tungsten tetrode fiber can be delivered in two different tip
shapes:
A) Tip pulled and ground
This treatment causes a double conical tip shape with impedance values higher
than 1MΩ, well suited for brain regions with a high cell density or for recordings
in small animal brains like rat or mice brains.
B) Tip only ground
This treatment causes a tip shape like a pencil tip (standard tip) with impedance
values lower than 1 MΩ, well suited for multi-unit or field potential recordings in
monkey or cat.
Figure 4: Tetrode fiber tip (ground)
3. Connector
Figure 5: Standard connector for the Tetrode (one for each channel)
4. Cable Length
The connection cables of the tetrode are made of silicone rubber insulated silver
wires. A gold plated Amphenol connector is soldered to the end of each cable an
isolated with a shrinkable sleeve.
Figure 6: Cable length
Attention! Standard connection cable length is 50mm. It is
recommended to keep the connection cable length as short as
possible. Anyway if you need longer cable please specify the required
length below.
Please be so kind and fill out the fax form at the end of this
document and fax it back to us to avoid any misunderstandings
concerning the electrode specifications. Thank you very much!
FAX-Message
TO:
FROM:
Company:
Thomas RECORDING GmbH
Name:
Name:
Dirk Hoehl
University:
Address:
Winchester Strasse 8
Institute:
Europaviertel
35394 Giessen
GERMANY
Fax:
Fax:
++49-641-94414-14
Pos. Specifications (Please add additional documents if required! Thank you)
1
2
Fiber strengthened with
Glass pipette o.d.=1mm
Glass pipette o.d.=1,5mm
Stainless steel tube o.d.=30 gauge
Stainless steel tube o.d.=31 gauge
Pipette Length (L1)
L1=60mm
3
7
mm
L1=
mm
Fiber protruding out of the tube (L2)
L2=
mm
Standard length is 50mm. If you should need longer cables please be so and and specify below:
Cable Length (L3)
6
4
Metal Tube Length (L1)
L1=
5
L1=80mm
L3=
mm
Fiber tip shape:
pulled & ground
(Z>1MΩ)
Article number: MEF9514264Cpg
only ground
(Z<1MΩ)
Article number: MEF9514264Cg
Custom-made adaptations:
Date:
__________
Name: ___________________
Sign: __________________
TETRODE
Adaptation to neural network density
Product Information
CORTICAL RECORDING
Cortical recording made with a tetrode (ground tip)
Figure 1: Cortical recordings, on a long time scale, to show the relatively high signal-to-noise
ratio.
(Recordings are made by Dr. Stuart Baker, University of Cambridge, UK with a 64 channel Eckhorn Microdrive)
Cerebellar RECORDING
Cerebellar recording made with a tetrode (ground tip)
Figure 2: Cerebellar recordings, on a long time scale, to show the poor signal-to-noise ratio.
Cerebellar recording made with a tetrode (pulled & ground tip)
Figure 3: Cerebellar recordings, on a long time scale, made with a tetrode with pulled & ground tip
to show the very good signal-to-noise ratio.
Result:
If one uses a tetrode for recording in different brain areas with different densities of
neurons it is recommended to adapt the spacing between the different recording sites of
the tetrode.
A standard tetrode has a tip that is only grinded to get a tip shape comparable to a
pencil. This kind of tetrode is very well suited for cortical or deep brain recordings in
humans or monkeys. In this case site impedance values of 400kΩ-800kΩ are well suited
to get a good tetrode effect (see picture below).
If one wants to record from brain regions with higher cell densities (e.g. cerebellum) or
from brains of small animals (e.g. rats) it can be urgently required to adapt the intersite
spacing to get a good signal to noise ratio and a good tetrode effect. In this case it is
recommended to pull the tip of the tetrode a little bit out before it is grinded afterwards.
The intersite spacing is reduced and the individual site impedance increases a little bit.
Usually site impedance values of app. 900kΩ-1MΩ are well suited to get a good tetrode
effect.
The quartz-platinum/tungsten tetrode design from Thomas RECORDING GmbH is
the only tetrode design presently available that makes it easily and reproducible
possible to adapt the intersite spacing to different neurophysiological
applications!
Figure 4: Tetrode tip that is only
grinded to get a tip shape like a
pencil (for further explanation see
text above).

4 Core Multielectrode

Transcription

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