Wearable biosignal monitoring nodes for real-time electrocardiogram and motion measurement

In this investigation we have implemented a wireless biosignal monitoring system for the real-time electrocardiogram (ECG) and the motion measurements, based on the latest wireless sensor network technology. We utilize the TinyOS 2.0.x operating system for providing services such as sensing, computing and wireless communication. We position one node on a belt worn by a subject for detecting the ECG, and the other node on the right-leg for detecting a single axis accelerating signal. The ECG is synchronized with the accelerating signal by radioing the signals simultaneously at the 868 MHz ISM license free frequency band to a base station (i.e. PC). The PC is used for displaying and storing the real-time ECG and motion signals, as well as to send commands (such as a new sampling rate) to the nodes whenever necessary. This work demonstrates the ability of using TinyOS-based sensor nodes for fast prototyping of a wirelessly linked, low-cost and low-power medical device.