Epoxy-Insulated Stainless Steel Microelectrode

Epoxy-Insulated Microelectrodes are consistently high-quality electrodes available in either Stainless Steel or Tungsten. We know that electrodes are difficult to manufacture, therefore we take extra care to monitor each step of microelectrode fabrication. Microscopic inspections are performed and microelectrode resistance and capacitance are checked to ensure insulation integrity and proper electrode impedance.

Metal electrode impedance is measured with a 2 nAp-p current at 1 kHz. The tolerance range for 5M epoxy-insulated microelectrodes is 3M to 8M, and the tolerance range for 12 M epoxy-insulated microelectrodes is 10M to 18M. We skew the values a little high because it is possible to lower the impedance at a later stage by passing current through the electrode.

Metal electrodes do not behave as resistors due to polarization. They have low series resistances for high frequency signals and high series resistance for low frequency signals. For example, for DC inputs a typical tungsten microelectrode will have a series resistance of about 200 MΩ. However, for a 1 kHz sine input, the same electrode will have an impedance of 1 MΩ. Its impedance will further drop to only 100 kΩ for a 100 µs pulse.

Note: Estimated lead time for all electrode orders is 2-3 weeks from the order date. Orders over 5 boxes might take longer.

Because of Parylene-C's superior performance and stability as an electrode insulator, A-M Systems no longer offers epoxy-insulated electrodes and instead is expanding Parylene-C insulated tungsten electrodes offerings.

Parylene-C electrodes show more impedance stability and have proved to be an excellent recording and stimulating electrodes.

The chart below indicates the suggested replacement Parylene-C products for the discontinued Epoxy-Insulated Stainless Steel Electrodes. Blue cells indicate differences in the suggested replacement electrode from the current model.

Please note that additional Parylene-C impedance options are available, as noted on the Parylene-C Tungsten Microelectrode page.

Parylene-C Replacement Electrode Chart

Epoxy-Stainless Steel Shaft Diameter (In.) Impedance (MΩ) Tip Shape (°) Parylene Replacement Shaft Diameter (In.) Impedance (MΩ) Tip Shape (°) Material