Cardiograph is an Android app that can be used to measure the heart beat rate for any human being. It uses the built-in smartphone camera for measurement of the heart beat rate. There is no special instrument needed for the Cardiograph app to work. The only thing you need is an Android smartphone with a back camera that comes with an LED flash.
The Cardiograph app requires some permissions before we can use it. The first permission is to access and use the device camera. It needs the camera to measure the pulses of blood flow in the fingers. When it gets permission for using the camera, it also gets the permission for the LED flash. The second permission it needs is for fetching the device location. It needs the device location so that can save the location along with the heart beat rate records.
When you have given all the permissions, you can put your forefinger over the camera lens and then tap on the Start button in the Cardiograph app. If your smartphone comes with a camera having multiple lens, then you should put the finger over the lens that has the largest megapixels. For example, my Android phone has two lenses in the rear camera – 16 megapixel and 8 megapixel. I placed my first finger (also called forefinger) on the 16 megapixel lens.
It will turn on the LED flash and start measuring the change of color in the blood stream which indicates the heart beat. A heart beat graph is displayed on the screen of your smartphone. This resembles to what you might get through an Eletro Cardio Graph (ECG). However, the developers of the app have put a disclaimer (and rightly so) that the app is not a replacement for a medical equipment even though it is accurate to a certain degree.
All the heartbeat measurements can be saved to the local storage. They include the time and the location where you measure the pulse rate. You can also include the activity level of the person when the measurement was take such as resting, warming up, cardio, or extreme workout.
You can get the Cardiograph app for Android from https://play.google.com/store/apps/details?id=com.macropinch.hydra.android.