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What is ECG Sensors, In A Nutshell You Should Not Miss!

It is the 21st century & no more Heart Rate tracking is in shadows by the grace of gadgets like ECG sensors. We have all heard of HR trackers, sensors, straps, vests etc that track heart activity. Just rewind a few years back was all this thing possible? Were we able to monitor our HR? This has become possible because of advancing study in the medical field.

So, we will see how this tracking happens using a particular tool as known by you – ‘ECG Sensors’.

Note before moving ahead –
This is a bit technical so focus and enjoy.



Let’s start by understanding the use of HR Tracking. Do you love someone and haven’t conveyed your feelings to your crush? How do you feel when you see your crush? Let me tell you your heart beats like an experienced drummer, doesn’t it? This same activity is observed when you see someone threatening you. Many events occur in a day when you feel this activity.

This concludes that the way we react is linked to our heart activity. Emotions can be detected by interpreting heart activity. However, this is beyond the scope of this post. In the additional analysis, we will see how HR tracking is performed and how it benefits us to monitor our health.

Who brought ECG to practise?

It was in 1903, the early 19 century. When a Dutch doctor and physiologist Willem Einthoven invented the first ever practical ‘Electrocardiogram’, abbreviated as ECG/EKG.

Further, he earned the Nobel Prize in Medicine in 1924 for his contribution…

What is an ECG?

An Electrocardiogram[ECG] is a test that measures your heart’s rhythm and electrical activities. Comprehending this data can help a specialist to draw a result that your heart is working normally or not. We will discuss what diseases it can be detected by this in the later section.

Engineering Behind ECG

  • The ECG test is carried out with the help of some electrodes and conductive materials/gels. The electrodes are generally made up of Silver-Silver Chloride electrode[Ag/AgCl]. According to this setup, the conductive material used is AgCl. The resistivity of this gel is set to about 100 Ω·m.
    There exist a standard nomenclature [] to label the various electrode positions. We all know electricity flows in our body through neurons. The heart sends electrical signals when it beats. This signal is highly sensitive to the frequency at which the heart beats.
  • Typically, the heart conducts electricity in a standard pathway from the right atrium to the left atrium. The electrical current then goes to the atrioventricular (AV) node [electrical relay station between the upper and lower chambers of the heart], which signals the ventricles to contract. The current then flows to an area known as the bundle of His. This area divides into fibres that provide current to the left and right ventricles.

Why all this? Because the electrodes detect these signals.

Let us understand how…

There are in total four electrodes. These electrodes are placed around the chest. Don’t worry you won’t have to deal with an electric shock or some similar stuff. They are placed on your body to give a path to the electrical signals outside your body. To enhance the flow of the current, conductive gel is applied to the electrodes and the skin.

Hence, ECG is known to use wet sensors. According to the signals, patterns can be obtained on the paper or on a screen. The same is depicted in the image below.




The overall test takes not more than a few minutes. Moreover, the equipment is portable and electrodes of such capabilities are cheap and available in the market. But conducting the test is cumbersome as you have to place few electrodes and apply conductive gel too. Therefore, to avoid all these ECG sensors are developed. These sensors are used in the gadgets that stays by our side for a long time. This empowers us to have a regular eye on our HR. But using an electrode to measure the signals from only one body area affects the accuracy to some degree.

Nonetheless, technology is advancing and these methods are becoming more and more certain. Watch this a very basic and easy demonstration of the working.



If you are fired in knowing how this data is described.

Is your ECG test date coming soon?

Varieties of ECG

In total there are 3 different varieties of ECG testing –

Resting ECG

  • This type helps you to understand how your heart is performing when you are relaxed. So, to conduct this test you have to relax, do yoga or meditate while the reading is being taken.

Exercise or stress ECG 

  • You can use this variation to understand your HR during stress or performing intense activities. This aids you to identify how much stress or intensity makes your heart to pump at a faster speed. So, you can prevent your blood pressure from rising.

Ambulatory ECG

  • The above two varieties have a stop. Those are discrete processes. But, this is more continuous and less of discrete. This one can be achieved when you keep the HR feature of your fitness tracker always on. The significance of this is that you can monitor your heart activity for one day or more. This gives a detailed information on how your HR patterns changed throughout the day.

What does ECG detect?

ECG is a useful way to find out whether your blood pressure is about to or has already caused any damage to your heart.

Some of the events detected by ECG readings –

  • A heart attack occurred in the past.
  • Enlargement of one side of the heart.
  • Abnormal heart rhythms.
  • Clogging of your heart’s blood supply due to cholesterol.

Some gadgets with ECG sensors

  • Fitness Trackers
  • Smart Watches
  • Chest Straps etc [QardioCore]
  • Clothing [Hexoskin Garments]

Are ECG Sensors Safe?


Positively Yes, they are safe. As no current is delivered. There is no reason for you to imagine surviving a shock. Moreover, the composition of the electrode and the conductive gel has no fatal effect on us.

Only concern is that you might encounter rashes when the electrode is in contact with your skin. This will happen if you have a very sensitive skin.




The following points summarise the entire post.

  • Emotions affect heart activity.
  • Willem Einthoven invented the first ever practical Electrocardiogram.
  • ECG tests are carried out using electrodes and conductive gels.
  • Your heart produces electricity in sync with its beats.
  • This electricity is detected using the ECG setup.
  • This technology is now used in small sensors, called ECG sensors.
  • The principle of working of ECG sensors is same as of ECG test.
  • Use of ECG can help diagnose.
    1. Abnormal Heart activities.
    2. Past Heart Attacks
    3. The rhythm of the heart.
    4. Heart Enlargement.
    5. Clogging of heart’s blood
  • Today, ECG sensors are available in many wearable gadgets.
  • The usage of ECG sensors is not a threat to mankind.

Thank you for reading. Moreover, share this to your near and dear ones so that they also uncover what ECG sensors are and how they function. As sharing knowledge increases knowledge universally.




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