Directly conductive, flexible, 3D printed, EEG electrodes

Abstract

Electroencephalography (EEG) is the non-invasive monitoring of the electrical activity in the brain, and forms a key part of Brain-Computer Interfaces (BCIs). Traditionally EEG instrumentation has been connected to the head using wet Ag/AgCl electrodes in the shape of a (typically) 1 cm disc. However, the conductive gel used increases set up time, and all the electrodes are the same size and shape for all users and head/hair shapes. Recently 3D printed EEG electrodes have been proposed to allow personalised EEG electrodes. However, to-date these have relied on printing a base structure which is then coated in Ag/AgCl. This paper presents 3D printed EEG electrodes using a directly conductive filament. The resulting electrodes do not require a conductive gel or coating, can be personalized, and cost less money and manufacturing time. The new electrodes are characterized in terms of electrical resistance, skin contact impedance and mechanical strength, all showing an acceptable performance. We demonstrate their use for recording Steady-State Visual Evoked Potential (SSVEP) brain responses in comparison to wet and dry Ag/AgCl electrodes.