Said detector includes a first bias electrode and a first measurement electrode.

The biosensor (1) includes working (4) and counter (5) electrodes.

At least one measuring electrode (E1, E2) is assigned to the measuring tube (5), and a measuring current (i) that depends on the flow of the measuring medium is induced into said measuring electrode.

Some tool embodiments have a sensing surface that comprises: a measurement electrode, a focus electrode surrounding the measurement electrode, and a return electrode surrounding the focus electrode.

Said sensor unit contains a transmitter electrode (3), a measuring electrode (2), interspaced from the top of the transmitter electrode and opposite thereto, and a shielding electrode (4) surrounding the measuring electrode (2).

The apparatus may include at least one measure electrode.

An electrochemical cell (20) includes a measuring electrode (12) and a reference electrode (14).

The measure electrode (7) and the counter electrode (18) are surrounded by screening electrodes (11, 21).

A measuring electrode (27) and an adjacent electrode (28) are embedded in an insulating substrate (26).

A measuring electrode is arranged in the measuring gap with a guard electrode arranged to both sides thereof and insulated therefrom.

This inclinometer is also fitted with measuring electrode (6).

In this type of measurement, the potential difference between the indicator electrode and a reference electrode is recorded.

This electrode forms the measurement electrode of an oxygen pressure sensor.

A measuring electrode (13) is disposed in the central area.

The reference electrode can be suitable for use with a separate measuring electrode, or can be combined with a measuring electrode in a single unit electrode assembly.