Development of a Patch-Type Electrocardiographic Monitor for Real Time Heartbeat Detection and Heart Rate Variability Analysis
It is essential to perform real time monitoring of the cardiac and physical activities in patients with cardiovascular diseases. Thus, the objective of this research was to develop a one-lead electrocardiogram (ECG) patch monitor for the detection of heartbeats and the calculation of frequency-domain parameters (as a mental index) of heart rate variability in real time. Consisting of a microcontroller with ARM 3 core and embedded with a three-axis accelerometer, this monitor could real time provide some additional information related to user’s daily physical activities. Main specification items of the ECG patch monitor were found to meet the standards of the International Electrotechnical Commission for medical electrical equipment and ambulatory electrocardiography systems (Holter ECG system). Its ingress protection rating, for instance, was found to be 68°. Thus, the ECG patch monitor allowed users to put it on all day, and to do various kinds of exercises or sports, even including swimming. In order to let users feel comfortable, it was designed to be of light weight and could run for over 24 h. A 4 GB flash memory was installed in the apparatus for data storage. The performance of the heartbeat detection algorithm was evaluated by using the MIT-BIH Arrhythmia Database. The results showed a sensitivity of 99.7% and a positive predictivity of 99.0% for the cardiac rhythm detection. Meanwhile, a mobile application algorithm allowed users to adjust some functions of the ECG patch monitor and to display the heart rate, mental index, and physical activities in 1 day. When users felt chest discomfort, they could push a button on the ECG patch monitor and 1-min ECG signals would be sent to the mobile device via Bluetooth 4.0. Based on the testing results, the patch-based ECG apparatus may be suitable for different types of users to apply in a ubiquitous healthcare environment, especially for those with a potential cardiac disease.