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Manufacturing micropipettes
for microiontophoresis and extracellular recording

Microiontophoretic assemblies are manufactured mostly from borosilicate glass capillary tubing. For the commonly used three- or seven-barreled multibarrel assemblies the appropriate number of tubes are fused or glued together before pulling. The two ends of this electrode 'blank' are then held by chucks (glassholders) of the micropipette or electrode puller and a heating coil is used to soften gently the glass in the central portion of the assembly. One of the chucks is then rotated while the electrode blank is pulled slowly. This rotation and pulling cause the lengths of tubing to fuse together. The combination of current supplies to the heating coil and the degree and timing of pull may be varied to produce pipettes of different lengths and diameters. The open ends of the tubes are bent outwards from each other (splayed) to facilitate access and to reduce cross-contamination when filling.
Here we introduce our Gravipull-2 micropipette puller. Its main advantages are:

Gravipull-2 micropipette puller	Innovative, new design Very smooth pulling Color of parts may vary Long slider travel Easy to learn and operate The Gravipull-2 will work with borosilicate or aluminosilicate glass capillary tubings or rods up to 6" (150 mm) long. It will not pull 'high' melting point capillary tubing such as quartz. The electrode blank is fixed in the upper and lower chucks while the upper one is held in place by a locking screw. A Start button on the front panel begins the pulling cycle. The pull is by gravity using an 8-stage weight system. The lower chuck can be rotated once the glass begins to soften. A damper in the bottom of the puller arrests the lower glass holder gently so as not to damage the lower piece of glass. The heater automatically switches off at the end of each cycle. There are three variable control functions on each puller: (1) The heater current is continuously variable via a 10-turn rotary knob. (2) The number of turns in the heater coil greatly affects the taper length. (3) The pulling force is set by the appropriate number of weight discs. Specifications: Max. blank dim.: 0.25"diam x 6.0" length, (6.4 mm x 150 mm) Slider's travel: Vertical, 4" (100 mm), The longest in its class! Heater current: Regulated between 1 and 16 A at 12 VDC Display: Reflective 4-digit LCD Power source: 115 VAC or 230 VAC, Manually selectable Mains frequency: From 40 Hz to 60 Hz Power cord: With options of US, Euro, UK or AUS plugs Dimensions: 11" x 25" x 13.5" (28 cm x 63.5 cm x 34 cm) (Width x Height x Depth) Weight: 32 lbs (14.6 kg)
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Every electrode shown in this web-site was made with a Gravipull-2 puller.