Abstract: In an embodiment an electrochemical cell includes a first electrode having a first surface area A1, a second electrode having a second surface area A2, an electrolyte arranged between the first electrode and the second electrode, wherein the electrochemical cell is configured to provide a first electrochemical half-cell reaction at the first electrode and provide a second electrochemical half-cell reaction at the second electrode, and wherein a surface area ratio A1/A2 is larger than a stoichiometric ratio of the first half-cell reaction and the second half-cell reaction.

Abstract: In an embodiment a sensor device for arrangement on a mouth-nose protection includes a sensor unit having at least one sensor element configured to detect individual breathing processes of a user when the mouth-nose protection with the sensor device is used by a user and an evaluation unit configured to count the breathing processes of the user depending on a detection signal provided by the sensor unit and provide an evaluation signal for a signaling unit depending on a determined number of breathing processes.