From Fredrick Haer Company

Needlecraft^TMmetal micro and stimulating electrodes are used by hundreds of research investigators worldwide. The configurations below are recommended for most recording and microstimulating applications.

These Platinum/Iridium (Pt/Ir) electrodes have a .010" (250 micron) shank diameter and a standard length of 60 mm, with an 8 mm gold pin terminal. Pt/Ir electrodes with blunt profiles are recommended for cortical recording with the dura removed. Finer profiles track better for deep recording.

Metal microelectrodes are stocked in two impedance ranges corresponding to 5 microns exposed tip length (8MOhm impedance at 1000Hz) and 25 microns (3MOhm impedance). Higher impedance electrodes are ideal for recording from single cells in deeper structures. Electrodes with a lower impedance are recommended for stimulating, or recording from, large or multiple cells.

Generally, the larger the exposed tip length (the lower the impedance), the greater number of cells from which potentials will be recorded. Also, the deeper the recording site, the higher electrode impedance is required. A complete line of electrodes from FHC is available from Stoelting. Please call for assistance in selecting the best configuration for your research application.