A device for detecting the presence of at least one human finger on a surface, comprising: - at least one element having piezoelectric characteristics and • comprising a layer of piezoelectric material on a metallic base plate arranged between a lower conductive layer and an upper conductive layer; • being located under a unitary surface, to which the element has been attached by an adhesive layer and which is visible and extends laterally beyond the layer of piezoelectric material and the base plate; and • arranged in the device in such a manner that a force when exerted on the surface, such as when the surface is pressed by finger, is transferred to mechanical stress of the element, the element then producing a voltage output in response to the mechanical stress; - means (R2, R3, C3, IC1) for measuring the voltage output in a predefined time period; and - means for determining the degree of stability of the measured voltage output, configured to indicate that: i) if the degree of stability shows that the measured voltage output is stable, a physical contact between a human finger and the surface does not exist; and ii) if the degree of stability shows that the measured voltage output is not stable but contains vibrations characteristic to a human finger, a physical contact between a human finger and the surface does exist. - at least one element having piezoelectric characteristics and • comprising a layer of piezoelectric material on a metallic base plate arranged between a lower conductive layer and an upper conductive layer; • being located under a unitary surface, to which the element has been attached by an adhesive layer and which is visible and extends laterally beyond the layer of piezoelectric material and the base plate; and • arranged in the device in such a manner that a force when exerted on the surface, such as when the surface is pressed by finger, is transferred to mechanical stress of the element, the element then producing a voltage output in response to the mechanical stress; • comprising a layer of piezoelectric material on a metallic base plate arranged between a lower conductive layer and an upper conductive layer; • being located under a unitary surface, to which the element has been attached by an adhesive layer and which is visible and extends laterally beyond the layer of piezoelectric material and the base plate; and • arranged in the device in such a manner that a force when exerted on the surface, such as when the surface is pressed by finger, is transferred to mechanical stress of the element, the element then producing a voltage output in response to the mechanical stress; - means (R2, R3, C3, IC1) for measuring the voltage output in a predefined time period; and - means for determining the degree of stability of the measured voltage output, configured to indicate that: i) if the degree of stability shows that the measured voltage output is stable, a physical contact between a human finger and the surface does not exist; and ii) if the degree of stability shows that the measured voltage output is not stable but contains vibrations characteristic to a human finger, a physical contact between a human finger and the surface does exist. i) if the degree of stability shows that the measured voltage output is stable, a physical contact between a human finger and the surface does not exist; and ii) if the degree of stability shows that the measured voltage output is not stable but contains vibrations characteristic to a human finger, a physical contact between a human finger and the surface does exist.