What is An EEG Cap?

What is An EEG Cap?

An Electroencephalogram (EEG) is one of the many tests used in neuroscience investigations. It is used in the observation of the irregularities of the brain waves or the electrical activity of the brain. The process involves placing electrodes onto the scalp. These electrodes are made up of metal discs with thin wires which are able to pick up the electrical charges that are produced from the brain cell activities.

An eeg cap mainly known as Electrode cap is used to aid in the electrode placement. This cap assists in the balance and precise placement of the electrodes to the scalp. There are two major types of EEG caps. They are:

  • Dry EEG cap
  • Wet EEG cap

The major differences between both types of EEG systems is the type of electrolytic substance which is put in-between the scalp and the electrodes to enhance the conductivity between them.

Dry EEG Cap

This EEG system does not need any electrolytic substance in-between. It makes direct contact with the scalp. They are easy and fast to wear and do not require any cleaning process after usage.

Wet EEP Cap

This system is further divided in 3 main types:

  • Saline EEG
  • Gel EEG
  • Water-based or Semi-dry EEG

Saline and Gel EEG

The Saline system makes use of saline solutions in aiding scalp contact while the Gel system makes use of electrolytic gels.

These systems are the most regularly used systems for EEG signals check. In order to reduce the hindrance between the skin and electrode interface, electrolytic substances which are extremely conductive are placed between the scalp and the electrode.

The gel or saline solution is applied to the scalp usually via an opening in the electrode. Sometimes before the electrode application, the skin is scraped a little to boost contact quality.

Water-based or Semi-dry EEG

In this system, tap water is placed in a permeable material which is used in-between the sensor and the skin. This helps in overcoming the use of gel and skin preparation.

The advantage of the wet EEG over the dry EEG is that they are easier to design and cost less. They also have a superior signal to noise ratio.

Things to note about wet EEG

  • Disinfecting procedures need to be carried out regularly on the equipment due to the electrolytic substances placed between the electrode and the skin.
  • Scraping of the skin is sometimes needed which brings discomfort to the user.
  • Cost of maintenance is higher because of the extra equipment it needs

Precautions before using an EEG

For many years, the EEG procedure has been considered a safe process. The possibility of getting shocked does not exist.

The EEG might cause seizures in persons with seizure disorders. This is caused by the flashing lights that occur during the test. The seizures will be treated instantly by the health care practitioner.

Depending on the patient’s medical history, other risks might be involved. Medical history should be discussed before the procedure is started


The use of EEG caps has opened up the world of neuroscience into new possibilities. Neuro-technology research and services has now become better and efficient.