Hello Guys, welcome back to this learning and building platform, today, we’ll discuss about Pulse Sensor. It is a quite famous sensor for measuring heart rate and other stuff. Pulse Sensor has a very simple construction and simple output. But this sensor lags in precision, which is a necessary thing in every type of this sensor. However, in this price range, such precision in measurement is highly appreciated, so for more precision, you should use different variants of such sensors. Keeping things straight, let’s begin today’s topic.
What is Pulse Sensor
Pulse Sensor, this is the smallest DIY sensor that can e used to measure Heart Rate and other essential measurements. This sensor comes in a circular PCB which is comparably smaller than other sensors available. Furthermore, it was not originally a sensor developed by some company but a kick-starter that gained popularity and further developed into a famous pulse sensor. As it is the very basic version of the heart rate sensor, hence the quality we expect from this is acceptable.
It is very simple and easy to understand, also as it is open source, there is no issue with the schematic, and its authenticity. Most importantly, the heart rate sensor, or precisely we say particle measuring sensors, works on the principle of Photoplethysmogram. This is the method of reading the intensity of the emitted light by the sensor itself. In this method, a light source is used which penetrates light rays into the skin, up to the blood vessels flowing under the skin. A photodetector is fixed such that it detects the light reflected from under the skin.
Photoplethysmogram
This method is commonly known as PPG, in addition, it has a wide range of applications and is growing further. In this method, a light source with is typically either IR-LED or GREEN LED is used. Certainly, some devices use both types for a more accurate reading and noise filtration. The Light Source penetrates the beam of light into the skin, which reaches up to the blood tissue. The light gets reflected from the blood components and detected by the photodetector and then further processed.
The values received by the microcontroller depend upon the intensity of reflected light received by the photodetector. Hence, the quality of the sensor used and the type of light are very crucial, on the other hand, there are different uses for the different light sources. IR-LED value is usually used to measure the blood volume, while the GREEN LED is used to measure oxygen in the blood. However, there can be another light source that can be used depending on the requirement.
Advantages
- It is a cheap and easy-to-use sensor, which is very good for practice as a beginner.
- No issues of messy communication or communicating with registers, simple single pin output
- Small and compact PCB with adaptable logic level range.