Axon Axopatch 200B, Theory Of Operation

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INSTRUMENT OPERATION • 57
Chapter 6
Holders
Features
The HL-U series holder provides for enhanced low-noise mechanically stable
microelectrode recordings with or without suction. Because the new holder provides a
universal fit for a very wide range of pipette diameters and will fit any of our redesigned
headstages, it is named the HL-U.
The barrel of the holder is made out of polycarbonate for lowest noise. There are two
different barrel lengths. The shorter barrel length contributes less to the operating noise
and, therefore, is ideally suited for single channel patch clamp recordings. Although the
longer barrel will contribute more to the operating noise, the increased length may provide
the needed clearance between the headstage and other components in the experimental
setup. Maintenance is simple because the holder can be fully disassembled for cleaning
and parts replacement.
Mechanical stability of the pipette is assured in several ways. For example, as the pipette
cap is closed, the cone washer is compressed on the pipette from the force applied to the
front and back of the cone washer. The holder mates with the special threaded Teflon
connector on U-type Axon Instruments headstages and is secured in place with a threaded
collar.
The holder is designed to emerge along the long axis of the headstage. A right-angle
adapter can be purchased if it is necessary for the holder to emerge at 90° from the
headstage.
The HL-U holder is designed to be used with Axon Instruments amplifiers, and fit all
U-type CV and HS series of headstages. These headstages have a
threaded white Teflon
collet. To minimize the added 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. This noise problem is peculiar to single-channel recording.