49
mm). Programs that can fabricate a pipette with these characteristics generally differ from
programs for micropipettes in three ways:
The trip velocity is lower.
Hard pull is not activated (PULL = 0).
More than one heating cycle is used.
The P-1000 can be used very effectively for this type of processing. The following general
information will familiarize you with the effect of adjusting each of the pull cycle parameters
in a typical patch pipette program. Following this general information are step-by-step
instructions intended to help you establish a stable program to pull patch type pipettes and
should be followed in the order described.
Consider the following sample patch program for 1.5 mm O.D. by 0.86 mm I.D. borosilicate
glass using a 2.5 x 2.5 mm Box filament:
HEAT PULL VELOCITY DELAY PRESSURE
Ramp 0 23 1 500
A program sequentially executes each line of code, then loops back to the start, and begins
again until the glass separates. A single line program such as this may execute 2 to 4 times
before the glass separates.
4.8.3.1 HEAT
The actual HEAT value used should be sufficiently high to allow the glass to melt in the first
cycle in 5 to 15 seconds. Using a higher HEAT that melts the glass in less than 5 seconds will
cause no problem in the first heating cycle, but may heat the glass so much in subsequent
heating cycles, that the air cooling will be less effective.
4.8.3.2 PULL Strength
A constant gravitational pull on the puller bars can be felt when loading the glass. This pull
is usually adequate to form relatively small-tipped pipettes (0.5 mm). Eliminating the hard
pull from the program (PULL=0) is recommended for most patch pipettes. If smaller tips are
required, a moderate PULL (25-50) may be used in the last line of a multi-line program (see
below).
4.8.3.3 VELOCITY (Trip Point)
VELOCITY determines the point at which the heat is turned off. If the value is too high, the
glass will separate after the third heat cycle. As the VELOCITY is decreased, the amount of
glass drawn-out in a given cycle will also decrease, and more cycles will be required to form a
tip. The greater the number of cycles, the larger the tip and the shorter the taper will be.
However, too many cycles can lead to variability. In general, it is advisable to keep the
number of heating cycles to 5 or less.
4.8.3.4 Cooling
TIME Mode:
When using thin-walled glass to make patch pipettes (slice patch), it is advisable
to keep the TIME between 200 and 250 to maximize the cooling of the glass.
P-1000 FLAMING/BROWN MICROPIPETTE PULLER SYSTEM OPERATION MANUAL – REV. 3.02 (20161118)
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