Electromagnetic Shielding of Fine Wires for Electrophysiological Sensing

Abstract: Tests have been performed to determine whether electromagnetic shielding of fine wires for electrophysiological sensing is a possible way to reduce the external noise in recording of nervous signals. By shielding the wires with a layer of silver, forming a coaxial cable, a reduction of the received power on the lead of 11.8-33 dBm was shown over the 10 – 10 000 Hz range when the test wire was subject to an electromagnetic field from an injection cable.  When putting the performance on the interval 50-100 Hz aside the same performance was measured to 25-33 dBm lower received power, which can be explained by 50 Hz noise from the electrical grid interfering with the measurements. However, when the shield was not grounded or grounded through a resistor worse performance was shown. The difference in received power between the unshielded and shielded configuration without grounding the shield was close to 0 dBm. Following this, the type of shielding investigated in this project has the potential to substantially shield thin wires from external interference under the condition that sufficient grounding is provided.