Physiological Data Collection

Skin Prep

Preparing the skin before placing sensors is a crucial step that is necessary to collect valid physiological data. We're measuring small changes that are impacted by numerous things, so thorough preparation is needed.

Before applying any gel or using any wipes on the participant, be sure to ask if they have any allergies, specifically to alcohol or makeup wipes. If so, use a paper towel dampened with distilled water instead.

Additionally, our skin prep procedures will remove any makeup and have the potential to remove spray tan, so make the participant aware of this before proceeding.

Galvanic Skin Response (GSR) Skin Prep

Either have the participant wash their hands with warm water and soap or wipe their left palm with a paper towel and distilled water. Do not use alcohol or anything else to clean the hands, as it can inflate the skin conductance response.

Electrocardiography (ECG) Skin Prep

Use an alcohol wipe to clean about an inch below the left wrist, an inch below the left elbow crease on the inner forearm, and an inch below the right elbow crease on the inner forearm. You should gently wipe about 10 to 20 times with an alcohol wipe in each of these areas.

Facial Electromyography (fEMG) Skin Prep

1. Wipe the participants face with a makeup wipe about 15-25 times in the following areas. Be sure to be mindful of wiping around their eyes. Increase the number of times you wipe if participant is wearing makeup.
   • The inner corner above the left eyebrow
   • The left cheek between the corner of the ear and corner of the mouth
   • Below the outer corner of the left eye approximately 3-4 cm below and some cm toward the outer side of the face.
2. Wipe the participants face with an alcohol wipe about 30-40 times each in the same areas.
3. Use a Q-tip to place a small amount of NUPREP gel in these same three areas. A little goes a long way! Be sure to place the gel close to where you will be placing the sensors, as too much gel or too far spread gel can pick up signals from other muscles that we don’t want to measure.

Sensor Placement

GSR Placement

Place the first sensor at base of the palm on the fatty part of the muscle below the thumb. Place second sensor right next to it towards to pinky finger. Place the sensors close together but not touching. This is the standard placement used in our lab.

Alternative placements include placing both sensors horizontally on the hypothenar eminence of the palm or finger placement. Test out these alternatives if you're worried that the activities in your experiment might mess with data collected from the standard placement.

ECG Placement

Place ECG sensors 1 inch below left wrist, 1 inch below elbow crease on left and right inner forearms. This is the standard placement used in our lab.

if you are concerned about the activities in your experiment impacting data collected from the standard placement, one alternative is to place two sensors just below the collar bone on the chest and one sensor about an inch below the left wrist.

If the sensor does not fully stick it is likely there was too much gel and it leaked onto the adhesive.

fEMG Placement

Corrugator Supercilii: Place the first sensor 1cm above inner corner of left eyebrow, second sensor 1cm over and half a casing up.

Orbicularis Oculi: Place the first sensor along the muscle ridge on upper cheek bone under the left outer corner of the eye. Place the second sensor 1cm from the first sensor toward center of face and half a casing down.

Be careful not to place the sensor too close to the eye, as it can pick up eye-blinks and make the participant uncomfortable.

Zygomaticus Major: Use a straight edge or your hand to draw imaginary line between corner of left ear and corner of left mouth. Place the first sensor in the center of that line on left cheek. Place the second sensor 1cm down and 1cm over towards center of face.

Connecting Sensors

Signal Chain