title: Microphonics in biopotential measurements with capacitive electrodes.
abstract: Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.
authors.affiliation: Instrumentation, Sensors and Interfaces Group, Castelldefels School of Technology, Universitat Politècnica de Catalunya (UPC), (Barcelona), 08860, Spain. luna@eel.upc.edu
authors.forename: Pablo S
authors.initials: PS
authors.lastname: Luna-Lozano
authors.forename: Ramon
authors.initials: R
authors.lastname: Pallas-Areny
mesh_terms: D016477:Artifacts; D025802:Electric Capacitance; D004566:Electrodes; D004569:Electroencephalography / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity