Adaptive Noise Reduction Algorithm to Improve R Peak Detection in ECG Measured by Capacitive ECG Sensors

Abstract

Electrocardiograms (ECGs) can be conveniently obtained using capacitive ECG sensors. However, motion noise in measured ECGs can degrade R peak detection. To reduce noise, properties of reference signal and ECG measured by the sensors are analyzed and a new method of active noise cancellation (ANC) is proposed in this study. In the proposed algorithm, the original ECG signal at QRS interval is regarded as impulsive noise because the adaptive filter updates its weight as if impulsive noise is added. As the proposed algorithm does not affect impulsive noise, the original signal is not reduced during ANC. Therefore, the proposed algorithm can conserve the power of the original signal within the QRS interval and reduce only the power of noise at other intervals. The proposed algorithm was verified through comparisons with recent research using data from both indoor and outdoor experiments. The proposed algorithm will benefit a noise reduction of noisy biomedical signal measured from sensors.

Sistema simples com eletrodos capacitivos para monitoramento da frequência cardíaca através de contato indireto

“…Também foi constatado maior deterioração do sinal quando usado poliéster ao invés do algodão como dielétrico, o que levou à não inclusão do poliéster nos ensaios com voluntários. Apesar dos altos valores de correlação e da comparação gráfica dos sinais (Figura 5) sugerirem que essa deterioração não representa uma preocupação para a interpretação do ECG, existem algoritmos dedicados à filtragem adaptativa de sinais ECG medidos por eletrodos capacitivos 24 .…”

Noise-Resistant CECG Using Novel Capacitive Electrodes

“…Next, the metallic plate was instructed to approach the subject at a constant speed, and signal-to-noise ratio (SNR) [20] is defined for quantitative comparison as:…”

“…In the former case, it is mainly the unwanted signals from other factors, or due to motion artifacts, of a subject. Interference from other parts can be filtered out as described in [9,19], while motion artifacts can be removed using an adaptive filter [9,20,21], soft electrodes [17], textile electrodes [22] or a sensor array [23]. In the latter case, it is mainly the common-mode noise, which can be further classified into stationary, e.g., power line noise, and nonstationary types.…”

A Wavelet Adaptive Cancellation Algorithm Based on Multi-Inertial Sensors for the Reduction of Motion Artifacts in Ambulatory ECGs

“…There are several studies on suppressing motion artifacts with adaptive cancellation algorithms. Seo [11] proposed a new noise cancellation method to suppress motion artifacts. Since an adaptive filter updates its weights as it adds impulsive noise, raw ECG signals at the R wave interval are considered to be impulsive noise.…”