Analysis of automatic detection of sphygmomanometer design points
With the improvement of people's living standards, medical monitoring equipment has gradually entered the family, and sphygmomanometer is a common medical device for household use. The sphygmomanometer uses a pneumatic cuff and monitoring device to measure blood pressure by listening. It can also measure blood pressure using a pressure sensor. This sphygmomanometer can be achieved in two ways: by manually inflating the cuff, using a stethoscope to monitor the sound of the arterial wall (auscultation), or by embedding a pressure sensor inside the sphygmomanometer to measure the vibration of the arterial wall (vibration) law).
There are two types of automatic blood pressure monitors: the upper arm sphygmomanometer and the wrist sphygmomanometer. The upper arm sphygmomanometer contains an air bag that is attached to the upper arm during measurement. The inflatable cuff is connected by a leather tube to a monitor placed near the arm. The wrist sphygmomanometer is small in size and the entire device can be wrapped around the wrist. Therefore, these products are more stringent in size. Some upper-arm sphygmomanometers require manual inflation, but most of the upper-arm and wrist sphygmomanometers on the market today are fully automated.
Measurement technique: The automatic electronic sphygmomanometer first inflates the cuff to provide sufficient pressure to prevent blood flow in the local aorta. As the pressure is gradually released, the measured pressure value is the systolic blood pressure when blood begins to flow through the artery. The rate of pulse beat can also be monitored. Continue to slowly deflate, so that the pressure inside the cuff is gradually reduced. When the cuff pressure is reduced to be equal to or slightly lower than the diastolic pressure, the blood flow is restored. The measured value is equivalent to the diastolic pressure of the heart. This completes a complete measurement cycle, which is done by pumps, pneumatic cuffs, electronic valves and pressure sensors in the unit.
The signal generated by the pressure sensor is conditioned by an operational amplifier or instrumentation amplifier and sent to the ADC. Then, for different types of sensors and monitors, the appropriate method is used to calculate systolic, diastolic, and pulse rate in the digital domain, and the resulting The result is displayed on the LCD screen, and the data and corresponding time/date are usually stored in the non-volatile memory.
Data interface
Some sphygmomanometers can upload data to a computer for more in-depth analysis and post-measurement tracking, and can transfer data over a USB interface. You can choose a discrete USB transceiver or you can choose to have this transceiver microcontroller built in.
Voice prompt: The audible indicator of the sphygmomanometer can be a simple beep or a high-end voice prompt. A simple buzzer can be driven by one or two pulse width modulation (PWM) output ports of the microcontroller; for advanced voice prompting functions, an audio digital-to-analog converter and amplifier can be selected to process the audio signal.
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