Gel Sensors

To achieve a high signal quality, you need to minimize impedance between the gel sensors and the scalp. Here are some tips to help you achieve the best quality signal:

Your participant should not use hair gel or other additives before fitting the sensors as these products can cause impedances.

• When cleaning the sensors or adding gel to the sensors, ensure you have enough light to see what you’re doing.

• Clean and abrade the skin under each sensor, then apply the electrolytic gel.

• You can use any conductive gel on the sensors, but some gels are better suited due to their viscosity or for a particular experiment. For example, when conducting a sleep study, using a gel that takes a long time to dry out is essential.

Suitable Electrolyte Gels

Salty or salt-free electrolyte gels can be used on the gel sensors. Here is a list of suitable products that you can use:

• SuperVisc (clear, high-viscosity, salty)

• Lectron III-10 (clear, medium-viscosity, salty)

• Abralyt HiCl (abrasive, high-viscosity, salty)

• Abralyt 2000 (abrasive, high-viscosity, non-salty)

• Nuprep Gel (abrasive, high viscosity, non-salty)

• Ten20 (opaque, high-viscosity, salty)

Preparing the Gel Sensors for Your Experiment

When preparing gel sensors for your experiment, you will need the following items:

• Cotton swabs,

• Isopropyl alcohol 70%,

• An abrasive electrolyte gel, such as Abralyt 2000,

• Conductive electrolyte gel, such as SuperVisc or Ten20,

• A plastic syringe without a needle (20ml), and

• Tissues to remove excess gel.

Cleaning Your Participant’s Skin

1. Move the hair below the sensor opening to one side, ensuring clear access to the scalp.

2. Add isopropyl alcohol to a cotton swab.

3. Gently rotate the cotton swab tip on your participant’s scalp to degrease the skin.

Abrading Your Participant’s Skin

1. Dip a cotton swab in abrasive gel.

2. Place the cotton swab into the sensor opening and rotate it gently on your participant’s scalp to abrade the skin. Do not apply too much pressure to your participant’s scalp. This process should be painless and not irritate the skin.

Filling the Sensors with Electrolyte Gel

1. Open the sensor.

2. Fill a syringe with electrolyte gel.

3. Insert the syringe into the open sensor and then push the gel out. When doing this, ensure that you make contact between the scalp and the sensor. Most electrolyte gels take a few minutes to permeate the skin.

4. Check the signal quality in PRO after preparing each sensor. The contact quality should be green.