MICROCAPILLARY ELECTRODES FOR INTRACELLULAR RECORDING 



Heating coil 



_ , / - - -^vT^^^'^P ^o"" tubing 

 = g ^\^\^ = ^r'^'^, =€) Sliding bar 



7-Toothed wheel 



I Spring 





Figure 35.2 Schematic drawing of a microelectrode pulling machine 



Another versatile mechanism, ascribed to J. W. Woodbury, is operated 

 on a scissor principle. The tubing clamps are mounted at the ends of scissor 

 action blades, as shown in Figure 35.3, operated by a spring causing them 



Spring 



Fixed pivot 



Clamp for 

 tubing 



Sliding 

 =« bar 



Heating 

 coil 

 Figure 35.3 Schematic drawing of a microelectrode pulling machine 



to Open. A sliding bar passing through both clamps maintains them 

 parallel throughout the action. The whole mechanism is pivoted and held 

 at one point. A horizontal U shaped heating coil is used, or a gas jet. This 

 machine can be readily constructed from simple parts, and also has the 

 advantage that the act of pulling withdraws the glass from the heating 

 element. 



Machines operated by solenoids — A reliable and commonly used type of 

 electrode pulling machine is based on the original pattern of Alexander 

 and Nastuk^^. This can give constant and repeatable results with a high 

 proportion of successes, and facilities are available for varying the type of 

 electrode produced. With this apparatus a two-stage draw is accomplished 

 by a solenoid acting on a concentric iron plunger carrying the glass tubing. 

 Power is derived from the mains supply. 



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