A two-axis gyroscope used on a bottom hole assembly can be used for determining a rate of rotation about the rotational axis of a BHA. The constraints associated with each approver are analyzed to identify a set of candidate change schedules for each time period of a number of time periods. Closure mechanisms control the introduction of the active substance and the suctioning off of the active substance in the manner, that the active substance after being introduced remains for a predetermined dwell time in the padding, before it is suctioned off. The sensing electrodes are spaced apart and arranged around the counter electrode to provide a spatially averaged value of the detected electrical signal.