Microelectrodes metal-through-glass

One method for producing a well-insulated microelectrode is to start with a glass capillary tube and bond it to an internal metallic wire. Several techniques exist. A low-melting-point metal can be used to fill the tube, or a wire of the same diameter as the internal diameter of the tube can be passed through the glass capillary, which is then heated to produce bonding. One must be careful to select glasses and metals which have nearly the same temperature coefficients of expansion. Three basic techniques exist as described below. 

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