cEEGrids are flex-printed, multi-channel sensor arrays that are placed around the ear using an adhesive. cEEGrids are very lightweight, comfortable to wear and unobtrusive. While they have been designed to enable multi-channel brain electrical activity (EEG) acquisition, cEEGrids can also be used to pick up other physiological signals such as eye movements (EOG) and cardiac electrical activity (EKG). The pictures show the current version, cEEGrid v 3. cEEGrid v 1 was introduced by Debener et al. (2015) and consisted of silver printed electrodes, etched copper wires and gold-plated connectors. The current version 3, in contrast, uses silver ink for all conductive parts: sensors, wiring and connectors. This allows for low production costs. In addition, the cEEGrid v 3 comes with a pre-attached adhesive to reduce overall preparation time. cEEGrid v3 is available commercially from TMSI and EasyCap.