Reference Section • 95
Chapter 5
Holders
• Design, use and maintenance of the HL-U electrode holders supplied with the
MultiClamp 700A.
The HL-U series holder provides a universal fit for a very wide range of electrode
diameters and will fit any of the U-type headstages of Axon amplifiers.
Holder Design
The barrel of the holder is made of polycarbonate for lowest noise. There are two
different barrel lengths (16 mm and 28 mm). The shorter length contributes less to
instrument noise and is therefore suited to single-channel patch clamp recordings.
Although the longer barrel will contribute more to the noise, the greater length may
provide the needed clearance between the headstage case and other components in the
experimental setup. To further minimize the noise contributed by the holder in single-
channel recording, the holder uses a small (1 mm) pin for the electrical connection and
a large amount of insulating Teflon.
Mechanical stability of the electrode is assured in several ways. (See Figure 4.13.) As
the pipette cap is closed, the cone washer is compressed on the electrode from the force
applied to the front and back of the cone washer. The cap also forces the blunt end of
the electrode against the rear wall of the holder bore. (The electrode should always be
inserted as far as it will go in the holder.) The holder mates with the threaded Teflon
connector on U-type Axon headstages and is secured in place with a threaded collar.
Figure 4.13. Exploded view of the HL-U holder.
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