A sample rate converter includes a digital filter and control logic coupled to the digital filter. A pair of spaced plates are attached to the frame 14 and an anchor member 34 is pivotally mounted between the plates for pivotal movement between an anchor position and a retracted position. A multi-channel detector with multiple detector elements receives the light spread by the spectral dispersive element and provides output signals indicative of photon events. The evaluation device is configured to determine a phase difference between a component of the measured signal, the component oscillating with a frequency, and a reference signal which oscillates with the frequency. As shown, the electrochemical cells are electrically and pneumatically connected in series so that the electrical current flow and the proton flow through the electrochemical cells are balanced. The first connecting portion is electrically connected with the second connecting portion, and the first connecting portion and the second connecting portion are located at the two opposite sides of the housing.