A sphygmomanometer is a device that measures blood pressure. It is composes of an inflatable rubber cuff, which is wrapped around the arm. A measuring device indicates the cuff's pressure. A bulb inflates the cuff and a valve releases pressure.

How does blood pressure measure work?

In a traditional analogue sphygmomanometer, the blood sounds are detected by the doctor using a stethoscope. As the cuff continues to deflate, it reaches your diastolic pressure, and the vibration stops. The meter senses this, and records the pressure again.

What is the principle of BP apparatus?

Oscillatory devices produce a digital readout and work on the principle that blood flowing through an artery between systolic and diastolic pressures causes vibrations in the arterial wall which can be detected and transduced into electrical signals.