Design And Realization Of Respiratory Monitor Based On Air-mattress

Sleep Apnea Syndrome (SAS) is a potential menace of human life and health,but it has not yet attracted broad attention.Sleep monitoring, especially respiratorymonitoring is an effective way to prevent SAS and evaluate sleep quality.There’rethousands of SAS patients in China, on the other hand there’s a huge loss of homemonitor market.Most of home sleep monitors are immature, and they can’t meetthe requirement of the new age home monitoring.We study mechanism and characteristic of physical quantity changes on humanbody and surrounding during breathing. We analyze and summary characteristic ofdifferent respiratory detection means.And according to non-contact and hassle-freerequirement of home monitoring,we choose respiratory signal detection based onmattress. By using analog circuit,digital circuit and signal processing technology, therespiratory monitoring system based on air-mattress is designed and realized.Firstly,In the aspect of structure design, differential pressure measurement andbalancing-tube is used to improve signal to noise ratio(SNR)of measuring system andreduce the possibility of sensor saturation.By developing appropriate mathematicalmodelling,the function of balancing-tube is illustrated.Secondly,signal conditioning circuit is designed according to characteristic ofrespiratory signal, including preamplifier, controlling baseline drift, a low-pass filter,and a second amplifier. The MCU STM32f103controls A/D converter(ADC)through the IIC interface and sets up amplitude regulation.Upper-lowercomputercommunication is realized using RS232Ccommunication protocol.Thirdly,by using Visual C++, monitoring software is realized on PC，includingserial communication,Waveform display and data storage..Algorithms for respiratoryevents through variable coefficient and respiration rate through waveformcharacteristics are designed and achieved.Function prototype is established. Experimental results show that the designedsystem can achieve the function of respiration rate detection and sleep apneamonitoring.It can lay a foundation for productization of sleep monitoring system.