For most biopotential recordings, it is important to provide a low impedance contact with the tissue underneath the skin at the electrode site. Consequently skin should be abraded with pumice, an ELPAD or ELPREP. Alcohol prep pads are generally not preferred because they dry the skin. The purpose of abrasion is to remove dead cells from the outer layer of skin. These cells form an electrical barrier. Electrical communication from the electrode surface to the underlying tissue is most often through a water-based gel. For good recordings, this gel must soak into the skin. As alcohol dries out the skin, it slows the process of establishing the liquid bridge between electrode and tissue.
One exception where abrasion is not recommended is measurement of electrodermal activity (skin conductance). Here skin should be rinsed but neither washed with soap nor abraded. As the conductivity of the skin at the electrode site is the variable to be measured in this case, no steps should be taken to modify that conductance artificially.
The NICO Smart Amplifier is specifically designed to measure thoracic impedance for performing noninvasive cardiac output measurements. The amplifier terminates in two connectors for impedance (Z) and its derivative (dZ), and has a 3 m cable that connects directly to an AMI100D Amplifier Input Module. Use with EL500 series disposable electrodes and LEAD131 for a four-spot […]
NIRS and CNAP—Pairing great tools for great data Cerebral hemoglobin concentration (blood mass in the brain) is frequently measured in the prefrontal cortex, and systemic arterial blood pressure is known to be a variable factor based on the hemoglobin concentration. A leg pressure cuff was used to constrict and release blood flow to create a […]
BIOPAC’s just released Introductory ECG Guide addresses fundamental to advanced concerns to optimize electrocardiography data recording and analysis. Topics include: ECG Complex; Electrical and Mechanical Sequence of a Heartbeat; Systole and Diastole; Configurations for Lead I, Lead II, Lead III, 6-lead ECG, 12-lead ECG, precordial leads; Ventricular Late Potentials (VLPs); ECG Measurement Tools; Automated Analysis Routines […]