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Laser etched bifilar fine wire electrode for skeletal muscle motor unit recording.
Nelson RM; Soderberg GL
Electroencephalogr Clin Neurophysiol 1983 Feb; 55(2):238-239
Single motor unit action potentials (SMUAP) of skeletal muscles were measured by using a specially developed bifilar fine wire electrode. Two fine wires of 8 micrometers (microm) in diameter and 25 centimeters long were twisted together to 3 centimeters, a hook was formed distally and the braided wire ends were insulated with lacquer. A 5microm piece of insulation was etched from each wire by a pulse laser near the hooked ends. Active recordings of the SMUAP were made from these two non insulated 5microm areas on the fine wire. The electrodes were evaluated for resistive and capacity components. Sixty four electrodes were constructed and examined for impedance components. Forty four subjects were tested. A total of 268 SMUAP were obtained. After intramuscular insertion, the fine electrodes were hooked to a high impedance probe of the preamplifier, with a high input resistance and capacitance of 10 pfarads per unit. The rejection ratio was 1000 to 1. The pulsed laser consistently produced 5microm apertures. The high resistance of the small aperture was offset by the higher input impedance of the probe of the preamplifier. The resistive components ranged from pfarads with an average dissipation factor of 0.480. The electrode was used successfully in all subjects tested. There was an absence of any interference signals during it-situ recordings of the skeletal muscle motor unit. The electrode was selective in recording from 1 to 5 SMUAP during isometric tension tasks ranging, from 5 to 30 percent maximum voluntary contractions. The authors state that with proper cleaning and sterilization, these fine electrodes can be used at least twice.
Electrophysiological-measurements; Physiological-measurements; Physiological-response; Musculoskeletal-system; Neuromuscular-system; Neurophysiology; Muscle-contraction; Nerve-fiber-excitation; Clinical-techniques
Issue of Publication
Electroencephalography and Clinical Neurophysiology
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