Pulse sensors have two types of output: analog output and digital output.
According to the way of collecting signals, it can be divided into three types: piezoelectric type, piezoresistive type, and photoelectric type. The photoelectric type is mostly infrared light.
Using the specific wavelength of infrared (typically 570, 870um) sensitivity to changes in blood volume caused by blood microcirculation at the end of the blood vessel, detecting changes in blood oxygen protein content in the blood at the fingertips due to the beating of the heart. After the circuit processing such as adjustment, it can output the pulse signal synchronized with the pulse beat to calculate the pulse rate, and it can also output a complete pulse wave signal that reflects the change in blood volume of the fingertip. Mainly used in clinical pulse rate measurement, monitoring and pulse wave pathology analysis. Blood oxygen saturation can also be calculated.
Generally, micro-pressure sensing materials, such as piezoelectric plates or bridges, are used to attach the probe of the sensor to the place where the arterial pulse is strong, and apply a certain pressure. The amount of electrical signal change is generated. After the signal amplification and conditioning circuit processes, the complete waveform of the pulse beat can be obtained, and a pulse signal synchronized with the arterial pulse can be further output. It is mainly used for the pathological analysis of cardiovascular diseases such as arteriosclerosis. There are also related studies on digitizing TCM pulses and networking pulse analysis.