by Dr. Thomas Emmerling
Scientific Consultant (Brain Products)
Our original actiCAP electrode was among the first active electrode systems available for EEG research. Since the release in 2005 the actiCAP has been widely adopted. Active electrodes have become the gold standard in research EEG – at least for applications where data quality is critical. And of course, quick, safe, and comfortable preparation for the subject are benefits that we do not want to miss anymore. Besides being an active electrode the actiCAP brought a unique combination of powerful features into a single device. If you are a current user of the actiCAP and you experience all the advantages of it every day, you can skip ahead and continue reading at “ What is new?“.
High impedance recording
High-quality Ag/AgCl pellets as well as active circuits are integrated into actiCAP electrodes. These make it possible to perform recordings at higher impedances than traditional passive electrodes. With this impedance conversion of the signal within the electrode, recordings outside a shielded chamber are feasible, too.
Per-electrode LED impedance feedback (patent pending)
Alongside the integrated impedance converter, actiCAP electrodes also contain electronic components, which enable the system to measure the impedances between the electrode and the scalp. Impedances still matter when recording with active electrodes ( see this paper by Emily Kappenman and Steven Luck). Multi-color LEDs in the electrodes indicate the impedance ranges (patent pending). This direct impedance feedback makes electrode preparation much faster and easier. For example, a 64-channel montage can be prepared in 5-10 minutes. Furthermore, our CapTrak system makes use of the LEDs for a fast and reliable optical electrode localisation.
Easy electrode replacements
The actiCAP electrodes are built for a long lifetime. With updates to the materials we made the electrode very sturdy. However, in the event that an actiCAP electrode would fail, it is possible to replace single electrodes very easily. In fact, the procedure takes less than 5 minutes and can be performed by yourself.
Wide hardware compatibility
Active shielding is an additional signal conditioning feature of our active electrodes. While active shielding is the only noise removal technique in some other products, in the actiCAP it is an optional feature. The active impedance conversion circuitry in the actiCAP electrode is the superior technology and will give you excellent data quality in most cases. In some very noisy environments using the active shielding in addition can lead to better data. However, be aware that active shielding has the capability to negatively impact your data quality as well.
All of these powerful features and the ease-of-use (make sure to have a look at the new hands-on active electrode guide in this Press Release issue!) have made the actiCAP electrodes very popular among our customers. Today, we present the next generation of actiCAP electrodes: the actiCAP slim.
What is new?
Smaller – Our engineers managed to fit all the features of the original actiCAP electrode in a new form factor that is three times thinner. Think about it: the actiCAP slim is a fully active EEG electrode with impedance conversion circuitry and multi-color LED impedance feedback scaled down by a factor of three.
Lightweight – The actiCAP slim is also lighter. The low center of gravity together with the lower weight reduces motion artefacts in EEG data. This makes the actiCAP slim an ideal companion for MoBI (mobile brain/body imaging) research. The lower weight per electrode makes a high-density cap significantly lighter and hence more comfortable to wear.
More robust – The new design of the electrode integrates the pellet into the housing of the electrode. This protects the pellet from accidental damages.
Easier preparation – Preparation of the actiCAP was always quick and easy. The larger opening in the actiCAP slim makes the electrode preparation even easier. It now allows the usage of paste for long-term recordings like in sleep research!
The lower profile of the actiCAP slim makes it ideal for TMS applications. While you can position the stimulator coil very close to the head you get the benefit of ultra-short artefacts due to the active electrode technology. For a more in-depth look at this application field, please have a look at the closed loop article in this issue of our newsletter.
We are excited to see our customers exploring the new possibilities that come with the actiCAP slim. Please note, that actiCAP slim electrodes are fixed into the fabric caps (like a BrainCap). Your local distributor will be happy to talk to you about the actiCAP slim and how it will make your research easier. The actiCAP slim is available since April 18th, 2017.