Moisture sensor

A use of a moisture sensor in a wound dressing, wherein the moisture sensor comprises a support substrate having a first face and a second face, geometrically opposite to the first face, and wherein:

• the first face is provided with a plurality of pairs of electrodes configured to be in contact with a liquid, and
• the second face comprises a plurality of first means of detection connected to each other in parallel, and
• each first means of detection comprises a transistor associated with a pair of electrodes, and
• said transistor of each first means of detection is configured to switch from a first state to a second state when an electric current passes between electrodes of the pair of electrodes associated to the transistor,
• an electrode of the pair of electrodes being electrically connected in series to an input electrode of the transistor and
• the other electrode of the pair of electrodes being electrically connected to a fixed potential, in particular, to an earth potential, and
• an output electrode of the transistor being electrically connected in series with a first resistor,
• such that the moisture sensor is sensitive to the equivalent resistance of said first resistors of the plurality of the first means of detection;
• and
• wherein the plurality of pairs of electrodes of the moisture sensor is arranged in the wound dressing to be in contact with a liquid from a wound.

A method for detecting moisture by means of a moisture sensor wherein the moisture sensor comprises a support substrate having a first face and a second face, geometrically opposite to the first face, wherein:

• the first face is provided with a plurality of pairs of electrodes configured to be in contact with a liquid, and
• the second face comprises a plurality of first means of detection connected to each other in parallel, and
• each first means of detection comprises a transistor associated with a pair of electrodes, and
• said transistor of each first means of detection is configured to switch from a first state to a second state when an electric current passes between electrodes of the pair of electrodes associated to the transistor,
• an electrode of the pair of electrodes being electrically connected in series to an input electrode of the transistor and
• the other electrode of the pair of electrodes being electrically connected to a fixed potential, in particular, to an earth potential, and
• an output electrode of the transistor being electrically connected in series with a first resistor,
• such that the moisture sensor is sensitive to the equivalent resistance of said first resistors of the plurality of the first means of detection;
• and
• wherein the method comprises the following steps of:
• a) measuring the equivalent resistance (Req) of the first resistors (R1) of the plurality of the first means of detection of the moisture sensor that is dependent on the number of transistors (T) switched in one of the first or second states, then,
• b) from the equivalent resistance value measured, deducing the presence of liquid on the first face provided with the electrodes.