Flexible inkjet printed sensors for behind-the-ear SSVEP EEG monitoring

Steady State Visual Evoked Potentials (SSVEPs) are a characteristic brain pattern that emerge in the Electroencephalogram (EEG) when a light source is flashed at a user. The EEG signal oscillates at the stimulation frequency, and this process forms the basis of many Brain-Computer Interfaces. This paper presents flexible inkjet printed sensors for the recording of SSVEPs. The flexible sensors obtain a capacitive connection to the body with an adhesive layer all the way under the electrode for maintaining a good body contact. The result is that SSVEPs can be recorded from behind a single ear without the need to use a conductive gel to lower the body connection impedance. The behind-the-ear location makes the electrodes very suitable for use in hearables and similar socially discrete wearable sensors for providing long term out-of-the-lab Brain-Computer Interfaces.