MOTION ARTIFACT SKIN

One of the major issues wearable biosignal monitoring systems face is the motion artifact. The monitoring of various bioelectric signals, such as electrocardiograms (ECG) and the electromyograms (EMG), has already been implemented into wearable systems.

MOTION ARTIFACT SKIN

We found that stabilizing the skin around the electrode using an electrode structure that manages to successfully distribute the force and movement to an area beyond the borders of the electrical contact area reduces the motion artifact when compared to structures that are the same size as the electrode area. The motion artifact and the induced impedance change were caused by the electrode motion and contained the same frequency components as the applied electrode motion pattern. For larger movements, the increase of motion generated a disproportionally larger artifact.

The relationship of motion artifact amplitude to the electrode movement magnitude is seen to be linear for smaller movements. The properties of tissue under the electrode are an important factor in the generation of the motion artifact and the functioning of the electrodes. Increasing the applied mounting force shows a positive effect up to 1,000 gr applied force. The design of the electrode support structure has an effect on the generated motion artifact good design with a skin stabilizing structure makes the electrodes physically more motion artifact resilient, directly affecting signal quality. With five subjects and two electrode locations placed over different kinds of tissue at various mounting forces, we simultaneously measured the motion artifact, a motion affected ECG, and the real-time skin–electrode impedance during the application of controlled motion to the electrodes. We compare four textile electrodes with different support structure designs: a soft padding larger than the electrode area, a soft padding larger than the electrode area with a novel skin deformation restricting design, a soft padding the same size as the electrode area, and a rigid support the same size as the electrode. In this study, we aim to investigate whether the structure supporting the electrode can be designed to reduce the motion artifact with the hypothesis that this can be achieved by stabilizing the skin deformations around the electrode. Reducing the motion and deformation at this interface should have positive effects on signal quality. The sources of the motion artifact lie in the skin–electrode interface. One of the main challenges facing the widespread use of wearable monitoring systems is the motion artifact. With advances in technology and increasing demand, wearable biosignal monitoring is developing and new applications are emerging.

Motion artifact