Studies On Non-invasive And Wireless Monitoring System Of Oxygen Saturation Of Blood

Blood oxygenation index is an important parameter that reflects the physiological state of the human body. The oxygen content of the blood, which is an important index when monitoring the vital signs, can be indicated by the densities of the oxygenated and deoxygenated hemoglobins in the blood.Traditional method of measuring blood oxygen is invasive. The oxygen saturation of blood is estimated by the blood lactate concentration. Although the result is accurate, it causes pain and discomfort. Also this method can't realize continuous monitoring. Especially for the critical patient or neonate, it is unrealistic to draw blood often. Non-invasive measurement is based on optical spectroscopy, which can get oxygen saturation of blood through measuring the change of the mere absorption quantity caused by the fluctuations of the blood capacity. The advantage of this method is safe, reliable, continuous, real-time, swift and non-invasive. It has been used widely on clinic and has become one of the common monitoring means in the operating room. It has made great contributions to the clinical medicine.In this paper, a non-invasive oximeter was designed, which adopted ARM microcontroller LPC2148 as the core unit and realized a wireless monitoring platform by nRF2401. The system is composed of three parts: signal acquisition, signal processing and wirless monitoring. Both the functions of signal acquisition and processing are finished by the LPC2148 micro-processor. The control signals genearated by the LPC2148 drive the red and infrared LEDs alternatively. The signals acquired by the photodiode are first amplified, separated and filtered to obtain two signals of the pulse which are then sent to the A/D converter of the LPC2148 for sampling and processing after which the oxygen saturation of blood can be obtained. Through the wireless channel, the data is sent to the computer. Then the information and status of every node can be monitored by the software running on the aforementioned computer. Users can collect data and monitor nodes conveniently.This non-invasive oximeter is proved by experiments that it eliminates the noise effectively and has good measurement accuracy. The wireless monitoring platform is stable. The whole system can monitor multi-patient's blood oxygen, break through space limitation, extend measuring range and achive the requirements.