Getting Started 3: What EEG Amplifier and Electrodes Should I Get?
Selecting an EEG Amplifier
Number of Channels
For many years, most training has been done with one or two channels. (Each channel produces a single EEG tracing.) The trainer can work with one or two sites, training them to do the same thing or different things at the same time, training relationships and linkage between areas. TLC offers a range of 2-channel amplifiers. The TLC Design Package for BioExplorer contains a full range of protocols for one and two-channel training.
TLC also offers a 4-channel amplifier. This allows training over a larger area—or more separate areas. Some trainers prefer four-channel synchrony training over two-channel. Because they are more difficult to set up and there is less demand for them, there are fewer four-channel designs, though the TLC Design Package includes several. And a 4-channel amplifier can train in one or two channels as well.
Multi-Modality
Some amplifiers offer options in addition to EEG. They can (with additional cables or sensors) train one or more of the older peripheral biofeedback measures, such as HRV, GSR, sEMG. The Optima amplifiers are multi-modality.
Comparison of 2 Channel Amplifiers
TLC distributes and supports three 2-channel amplifiers which work with BioExplorer. Each of them is available alone or in our convenient Training Packages. All of them sample the EEG at the standard 256 Hz. The Pendant has 12-bit resolution; the others have 16 bits. All produce very good signal quality.
Wireless Pendant EEG
At $595 the Pendant is the least expensive and smallest of the amplifiers. About the size of a cigarette lighter, it requires no cable to connect it to the computer. It communicates wirelessly with a receiver plugged into a USB port. It is light enough (about 1 oz) to clip on a client’s collar or sleeve. The Pendant focuses on portability and convenience. The downside of its size is that the 5 electrode plugs are tightly packed. It runs on a single AAA battery, and it comes with a USB battery charger and 2 rechargeable batteries. The Pendant is made of light plastic so it may be more susceptible to damage in handling. Its warranty is 6 months. Minder Labs is Australian. They have a US office to provide support if TLC can’t resolve a problem.
Focus USB EEG
At $600 the Focus is nearly the same price as the Pendant. It has a 3X5 inch footprint and weighs less than 3 oz. Most of the extra weight is in the heavy plastic case. The Focus connects to the computer via a USB cable, so no batteries are required. The electrode plugs are spaced and marked to make them easy to use. A 72-inch USB cable is included. The Focus is durable and generally trouble free. The warranty is 2 years. QDS Systems is an Argentine company. If TLC can’t resolve a problem with the Focus, it must be sent to Argentina for repair/replacement.
Neurobit Optima2
At $660 + $50 shipping from Poland, the Optima2 offers several additional features, including built-in impedance testing. Like the Pendant, it is wireless, connecting via Bluetooth (or a USB adaptor for computers that don’t have Bluetooth). It is a multi-modality amplifier. Heart Rate Variability, GSR, temperature, sEMG and other peripheral biofeedback measures can be measured with additional sensors. It uses 2 AA batteries, which are not included. The Optima has the same footprint and weight as the Focus but is half as tall and has an attached belt clip. The unit has a number of software controls. It comes with a two-year warranty. Neurobit Systems is a Polish company, and any problems TLC cannot resolve require shipping the unit to Poland.
Selecting Electrodes
You need electrodes, supplies for applying them, and in most cases a jumper for linking them. For an extended discussion on the selection and use of electrodes see our discussion About Electrodes and our video Placing Electrodes.
There are two basic types of electrodes: cup electrodes and snap-in disposable electrodes. The cup electrodes are more economical, because disposable replacements do not have to be purchased. The snap-in disposables are more convenient to use.
Cup Electrodes
The cup electrodes are always applied with conductive paste. We sell only high quality solid silver molded electrodes with a one year warranty. We do not recommend plated or stamped electrodes, which are easily damaged. The product pages for the cup electrodes and supplies tell you how many to order depending on your amplifier.
Snap-In Electrodes
The snap-ins consist of a lead that plugs into the amplifier and ends in a snap-in head. The disposable electrodes snap into the head. The electrodes used where there is hair are applied with conductive paste, but pre-gelled adhesive electrodes are used for skin placements, including reference electrodes behind the ears, and these are very quick and easy to apply. Again, the product page for the snap-in electrodes tells you how many to order.