Barbara: Today we're going to look at how to look at PASCO's Wireless EKG Sensor
to study the electrical activity of a person's heartbeat.
[Wireless EKG Sensor | Get Started]
The heart's pacemaker generates an electrical signal with each heartbeat.
EKG, also called ECG, is an abbreviation for electrocardiogram,
which is a visualization of that electrical signal
as it travels from the pacemaker to the upper and lower heart chambers.
The Wireless EKG Sensor uses electrode patches to pick up the heart's electrical signals
and transmit them to SPARKvue or PASCO Capstone software.
The first thing you might notice about the Wireless EKG Sensor
is it has a diagram that helps you correctly place electrodes on the test subject's forearms.
Line up the test subject's face with the smiling face on the sensor.
This is their right side, and this is their left side.
The sensor comes with a pack of 100 disposable self-adhesive electrode patches.
Before placing the patches in position,
the subject should wash the areas with soap and water
or use a cleansing wipe that contains no alcohol to keep the skin from drying out.
Have the subject grasp the patches by the non-adhesive tabs,
and place them in the forearm positions illustrated on the sensor diagram,
with tabs facing towards the abdomen.
One patch is placed at the left forearm just below the elbow.
Another patch is placed just below the elbow on the right forearm,
and another at the right wrist.
If necessary, pull the plastic alligator clip cover back to fully expose the grip area.
Clip the red electrode marked positive to the electrode patch on the left side.
Clip the black ground electrode marked R to the right wrist patch.
Clip the green electrode marked negative to the right forearm patch.
Be sure the clips are making the most contact possible with the conductive tabs.
We're almost ready to collect data.
The test subject should be seated away from the data display, or they can close their eyes.
Palms should be facing up, legs should be uncrossed, and the subject should be totally relaxed.
Now I'm going to connect the sensor to SPARKvue.
Notice when I connect the sensor a Quick Start Experiment becomes available.
So I'll choose that from my data display,
because it will show the EKG waveform as well as heart rate.
Before starting data collection, I'm going to remind the test subject to stay still and silent,
and to not look at the data display while I'm recording data. Are you ready?
Angela: Absolutely.
Barbara: Okay. I'm just going to collect a few seconds of data.
And now I've already stopped data collection.
My test subject can now speak and interact as usual.
Angela: Let's zoom in on one heartbeat.
Here's the beginning of one cardiac cycle known as the P wave.
The P wave begins to form when an electrical current is generated at the SA node or pacemaker,
and is passed along to the atria.
Atria begin to contract during the P wave, and pump blood towards the ventricles.
This downward pulse is the Q wave,
which indicates the electrical signal has reached the AV node, and the ventricles have begun to contract.
The electrical signal is strongest at the R wave,
because the main mass of the ventricles are contracting.
Ventricular contraction continues through the S and T waves,
as blood is pumped away from the heart out to the body.
The T wave represents relaxation and repolarization of the ventricles,
in preparation for the next cardiac cycle.
Repolarization of the atria is hidden due to the large signal general during ventricular contraction.
If you have noisy EKG data and it's hard to see the individual waves,
try smoothing the data.
Capstone has a smoothing slider,
but in SPARKvue you need to perform a calculation to accomplish smoothing.
Since we used the Quick Start file, we can just choose the voltage measurement,
switch to User Entered, and choose the SmoothedVoltage measurement.
Let's see how the data looks now. Make sure to scale the data.
You can customize the amount of smoothing.
Just go back to the User Entered menu and choose Create/Edit Calculation.
Adjust the number in the equation to an odd number five or higher.
Let's see what happens at 17.
We see the waveform is smoother, but you may notice the amplitude of each wave is smaller.
So it's up to you to decide whether to change smoothing or use the default setting.
Barbara: You'll find several formal lab activities in PASCO's Experiment Library,
such as Electrical Waves of the Heart, where students learn the basics of reading an EKG waveform,
and Heart Rate Recovery, where students compare resting heart activity
with heart activity after exercise.
You can also use an EKG sensor to study reflex response with the Muscle Stretch Response investigation.
On a final note, please remember that this sensor is designed for educational use only.
This is not a medical device, and should not be used in any apparatus involved with life support,
medical testing, patient diagnosis, or industrial control or testing systems.
Thanks for watching, and see you next time.