Quartz-Platinum/Tungsten Microelectrodes
Thomas Recording have developed novel single- and
multifibre electrodes for extracellular recording (single unit, multiple unit, local field potentials) and stimulation.
The electrodes are made of thin (20 to 120 µm o.d.) quartz glass fibre (insulation) containing a single core or multiple
cores of a platinum/tungsten alloy
(90/10). The melting point of the core alloy is matched to the temparature of a specific viscosity point of the
insulating quartz, allowing tips to be drawn as with conventional micropipette recording electrodes. In the drawn
tips, the quartz mantle and metal core both taper down to very small dimensions. The metal core is subsequently
exposed to the required tip size (and, hence, impedance) by grinding. Pulled and grinded microelectrodes (Z = 1
to 10 MOhm @ 1 kHz) are ideal for recording extracellular single-unit activity. For recording of multiple unit
activity or local field potentials, as well as for stimulation, no pulling is necessary, and grinding of the fibres
suffices.
Electrodes made from these fibres have outstanding recording properties:
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The diagrams on the left show a cross-section through
a fibre containing four Pt/Tu conductors, and the exposed conductors after grinding. The tip has been grinded to
an angle of 15° to 17°, exposing the central core as a cone and the peripheral cores as ellipses. |
 |
Another standard configuration is the heptode, which contains seven Pt/Tu conductors (not shown). Other core configurations can be made
to order.
Prefabricated grinded, or pulled and grinded
fibres of any length can be purchased. Raw fibre material can also be ordered, providing an economical solution
for laboratories using large numbers of electrodes. Thomas Recording also manufactures the special tip drawing
and grinding equipment. Please see below more detailed descriptions of the available prefabricated electrode configurations,
and of the "raw" Quartz-Pt/Tu fibre material and equipment for electrode fabrication in your own lab:
ELECTRODES FOR THE ECKHORN
SYSTEM *ESI2ec
Electrodes ready to use with the "Eckhorn
Matrix", pulled and grinded, with silicone guard tube, silver wire and gold-plated connector
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ELECTRODES FOR OTHER
MANIPULATORS *EF8025pgPip
Pulled and grinded, quartz/platinum-tungsten (90/10)
fibre electrodes strengthened with glass pipette, standard length 12 cm, with gold connector (male or female plug
as required). Outside diameter 80µm, core diameter 25µm tip will be grinded (impedance at 1kHz between
1-10MOhm) in accordance to your requirements.
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QUARTZ-PLATINUM/TUNGSTEN
FIBRES (RAW) *EF8025
(stock material for fibre electrode fabrication).
Outside diameter: 80µm, core diameter: 25 µm
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QUARTZ-PLATINUM/TUNGSTEN
FIBRES (GRINDED) *EF8025g
length: 25cm
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QUARTZ-PLATINUM/TUNGSTEN
FIBRE (PULLED & GRINDED) *EF8025pg
length: 25cm
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MULTIELECTRODE-FIBRE
WITH 7 CORES (GRINDED) *MEF100157Cg
fibre-diameter: 100-110 µm
length of fibre: optional
cores: 7,
ea. platinum/tungsten (90/10), diameter 7-8 µm
core-arrangement: concentric,
with center core
impedance (@1kHz): about
3 MOhm and up *
connectors: soldered
connections on micro board
* depending
on methods of pulling the electrode and grinding the tip
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table
MULTIELECTRODE-FIBRE
WITH 4 CORES (GRINDED)
*MEF9514264Cg
fibre-diameter: 95 -100 µm
length of fibre: optional
cores: 4,
ea. platinum/tungsten (90/10), diameter 7-8 µm
core-arrangement: concentric,
with center core
impedance (f=1kHz): about
3MOhm and up *
connectors: soldered
connections on micro board
* depending
on pulling the electrode and grinding the tip
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ELECTRODES FOR THE REITBOECK SYSTEM
*EFReitboeck8025pg
pulled and grinded
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ELECTRODE-TIP PULLER
ArticleNumber: ECKL-1.2
Small version, high-temperature tip puller with
helium-filled chamber for the pulling of quartz fibres with platinum/tungsten core (quartz-platinum/tungsten 90/10
fibre). About 50 cm (20") height, adjustable pulling force. A matching power supply (110V/60Hz) to heat up
the filament is provided. The tip puller ECKL-1.2 enables you to pull a standard tip in various sizes. The helium-filled
chamber with precise guidance of the electrode fibre is set-up like our model EL-1. The operation of this equipment
requires helium gas. Bottled helium is inexpensive and can be purchased e.g. from companies that sell bottled gas
for welding. During operation of this puller, very little helium is used.
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TIP GRINDING-MACHINE
ArticleNumber: DIECKL-ST
Precision diamond grinding disk manufactured using
quality engineering, balanced and without vertical error. The electrode will be fixed on a precise 1-dimensional
translation sledge with micro-motor for holding and rotating the electrode during grinding; the translation sledge
is adjustable in such a way that a tip angle of 15 degrees can be achieved. A special device moistens the diamond
grinding disk while grinding the electrode tip. The complete equipment is mounted on a base plate. The microscope
shown on the photograph is not part of this item and should be supplied by the user.
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