Fetrode™ noise reduction technology
Introduction
High impedance at the skin-electrode contact correlates directly with the amplitude of the noise artifacts that can plague bio-electric recordings. Historically, there have been only two ways to reduce such noise: 1) use the very best Ag/AgCl electrodes with a liquid-junction interface; and 2) abrade the skin to reduce the skin/electrode contact impedance. With the prevalence of HIV and hepatitis viruses, breaking the skin barrier is no longer advisable. Fetrodes™ minimize the requirement to abrade the skin.
The Fetrode is a unique, temperature-compensated amplifier with an extremely high input impedance and a very low output impedance. The circuitry is built with state-of-the-art surface mount technology into a miniature enclosure that can be snapped onto any high quality electrode. This innovation places signal buffering directly on the active electrode site. In so doing, the Fetrode virtually eliminates artifacts due to electrostatic potentials and cable noise, even with high electrode contact impedances.
In the comparison shown above, Ag/AgCl electrodes were applied to an adult male using the sternum/V6 electrode configuration, but without skin preparation of any kind. Gain was the same for both tests, approximately 1,500, and contact impedance between active electrodes was 120 KOhms. The UFI Model SRS2004/d performed the signal conditioning and data recording.
Three ways to take advantage of the Fetrode
- Order our Fetrode Bioamplifier.
- Order one of our BioLogs™ or Simple Scopes™ for bioelectric data recording.
- Contact UFI to add Fetrodes to your product. Interfacing is usually very simple.
Fetrode specifications
- Input impedance: 15 megohms typical
- Gain: 1 (unity gain)
- Bandwidth: DC to greater than 10 kHz typical
- Output signal: Input signal riding on 1-3V DC offset voltage
- Output impedance: 400 ohms typical
- Noise: 10 microvolts typical (DC to 1 kHz, +5V supply, per Fetrode)
- Supply voltage: +5V DC (typical), +9V DC (maximum)
- Supply current: 500 microamps typical (per Fetrode, +5V supply)
- Electrode connection: Standard female snap
- Size: 0.575" dia by 0.5" thick (14.6mm dia x 12.7mm thick)
- Weight: 0.2 ounce (5.7 grams; excludes lead wire)
Published references to the UFI Fetrode
