SUTTER INSTRUMENT

The Model P-97 micropipette puller is a Flaming/Brown type puller for fabrication of micropipettes, patch pipettes and microinjection needles.  While retaining many of the features found on the Model P-87, the P-97 offers improvements in the mechanical, electronic and software design.  The result is better control of the pulling process and a higher degree of reproducibility.

The P-97 combines a proven mechanical system with a sophisticated, programmable microprocessor controller.  This programmable control of the pulling parameters allows the investigator to design application specific pipettes from a wide range of glass compositions and sizes.

A number of new features have been incorporated in the design of the P-97. One of the most apparent is the  environmental chamber which houses the area surrounding the heating filament.  The humidity control chamber ^l is designed to minimize the effect of changing humidity on the reproducibility of pulled pipettes.   A 25% increase in power over the previous version allows for the use of larger heating filaments, larger diameter glass and multibarreled glass.  The metal jaws that clamp the heating filament have also been redesigned to  minimize heat retention.  A gas delivery mode switch provides for extended cooling for large diameter and multibarreled glass.  A springloaded clamping mechanism has been added for easier loading of glass.  A vacuum  fluorescent display has been added that allows easy viewing from any direction.

New software improvements include a display of the total time that the  heat is on to assist in program development and troubleshooting.  Up to 100 programs can now be written and stored in memory, which makes the P-97 more useful for multiple users.  These programs can now be  write-protected; this added security prevents programs from being changed or altered inadvertently.  When a program is written and saved it includes the date that it was written or edited.  The air pressure is included as  a programmable item.

The velocity of the glass carrying system is measured as the glass softens and begins to draw apart under a constant load.  The increasing velocity of the initial pull is determined by the  viscosity of the glass, which in turn is a function of the glass temperature.  The adjustable velocity allows for selection of a precise glass temperature as the point at which the hard pull is tripped².  The  puller operates on the principle of rapid cooling of the heating filament to give fine tipped pipettes with extremely short tapers, thereby producing stiff microelectrodes suitable for beveling.  Other benefits of the short  taper are reduced tip resistance and decreased capacitive coupling in twobarreled microelectrodes.

The P-97 contains a ramp-test to overcome the difficulties of program adjustment when a new filament is  installed or to help characterize a new glass/filament combination.  This test allows for the rapid adjustment of heat values in established programs and provides estimates for establishing heat settings when using new sizes  or compositions of glass capillaries.

As with all Sutter instruments, the electronics have been carefully designed to maximize noise rejection.

¹ Patent pending               ²Patent No. 4,600,42

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