| Active noise cancellation with Waveguard |
| By means of the shielded electrodes you are able to record quality EEG in conditions where conventional electrode systems will not work. For instance, when you are doing EEG/ERP research 'in the field' using a portable ERP system, you will not have your special shielded room with you. In these cases the active shielding of your electrode leads will still give you good quality recordings. Active shielding of the electrodes works only when the EEG amplifier and the cap are shielded. The asa-lab amplifier and WaveGuard cap system are the only products available that follow this innovative concept! |
Example The images on the right show a comparison between the power spectra of the EEG measured with a conventional cap (electro-cap, ECI) and that measured with the cap using the shielded electrodes. This recording was carried out in the USA in a normal EEG lab. No filtering was applied to the data. As you can see, the power spectrum of the conventional cap (shown on the left) shows a clear peak around the 60 Hz. Spectrum comparison and time-frequency plots of the signal at electrode CZ: using the Electro-cap (left), and the waveguard cap (right). Environmental noise is clearly reduced in case shielded electrodes are used! |  |
How does it work? The concept of the ActiveShield electrode can be compared to the working of the Faraday cage. Only now the Faraday cage is available for each individual lead! Each electrode cable ('core') is surrounded by a 'shielding'. The signal that is picked up by the electrode is actively fed back on the shielding resulting in a zero capacitance. This shields the signal in the core cable and prevents electrical fields from the outside to interfere with the signal in the core. The shielding is carried out for each electrode separately, resulting in the most optimal recording conditions. |  |
Key benefits of active shielding | ||||
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