Low power electrocardiography and impedance cardiography detection system based on LabVIEW and Bluetooth Low Energy

Due to the sporadic occurrence of cardiovascular disease, long term continuous monitoring is needed. An embedded wireless health monitoring system is designed and implemented, which is made up of wearable monitoring nodes with Bluetooth Low Energy (BLE) wireless transmission, a sensor data gateway and smart terminal etc. The wearable monitoring nodes are integrated electrocardiography (ECG) and impedance cardiography (ICG) sensors, which can not only detect ECG (indication of electric working status of heart) and ICG (indication of mechanical pumping working performance of heart), but also detect respiration, temperature, heart rate variability and moving status of the patient in real time. The low power of the sensor node is achieved through the optimized design of the circuit and firmware. The software architecture of the sensor data gateway with a WebSocket data server implemented is constructed with multi-thread mechanism and object-oriented method of LabVIEW to achieve stable waveform data transmission. Noise and baseline wandering of ECG and ICG are removed by Undecimated Wavelet Transform (UWT), which is also used in real-time feature extraction of ECG and ICG waveform. Test results show that the current-consuming of the sensor node in working state with BLE transmission is 11mA and 69μA for standby low power mode. The sensor data gateway supports connection with any mobile terminal device with Wi-Fi capability.