There is disclosed herein a sensor for detecting at least one of urination and excretion into an incontinence garment, the sensor comprising an activation unit and a sensing unit and being connectable to a power supply; the activation unit comprising: two spaced-apart electrodes, and a switch arranged in series between the sensing unit and the power supply; wherein the activation unit is configured to activate the sensing unit in the presence of moisture by closing the switch; and wherein at least one of the sensing unit and the activation unit comprises a latching circuit arranged such that the activation of the sensing unit is irreversible. An incontinence garments such as the diaper is incorporating such a sensor is also disclosed as it is a method for operating such a sensor or incontinence garment.