Performance of graphene ECG electrodes under varying conditions.

Smart garments for invisible health sensing have been available for a number of years, with heart sensing typically performed using silver loaded conductive threads integrated into the fabric to pick up the electrocardiogram. Recent work has investigated printed graphene textiles as an alternative to this, which are potentially more environmentally friendly, cost-effective, and can be performed after garment manufacturing. This paper presents an exploration of second order factors on the performance of graphene textile electrodes for electrocardiogram measurements. We prepare graphenebased textile electrodes using a simple and highly scalable continuous padding method. We then analyze two metrics: the change in heart rate estimation error, and the changes in signal-to-noise ratio; under two separate conditions: an extended record length, and varying temperatures; to recreate the some of the conditions the material would experience when being worn in real-life. We report that neither the heart rate estimation error or the signal-to-noise ratio are significantly affected after a long record or with varying temperature. These tests indicate that graphene electrodes are suitable for electrocardiogram measurements in a wearable that will be subjected to these conditions.