A device, comprising: a matrix of piezoelectric sensor elements (11A - 11P) comprising rows of the piezoelectric sensor elements and columns of the piezoelectric sensor elements; measuring circuits (21A-21H, 31A-31H) configured to detect at least one touch, wherein the measuring circuits are configured to the rows and to the columns; and a wake-up trigger (14,143,145,33) configured to detect the at least one touch and further configured to trigger the matrix to an operation mode when the at least one touch is detected; characterized by the wake-up trigger is connected between the common reference net for the rows of the matrix of piezoelectric sensor elements and the common reference net for the columns of the matrix of piezoelectric sensor elements and the wake-up trigger is configured to monitor a voltage difference between the isolated common reference nets, wherein the wake-up trigger further comprises a switch 14) and a high ohmic resistor permanently coupling the two reference nets, wherein the switch is an isolation switch, which disconnects the two separate common reference nets (141, 142), so that the voltage difference between the two common reference nets can be detected and wherein the wake-up trigger is configured to connect and disconnect the isolated reference nets by the switch and accordingly turn the switch on for activating the matrix to the operation mode, wherein the measuring circuits comprise signal conditioning filters (21A-21H) and detection devices (31A-31H), the isolated common reference nets comprise a common reference net for the rows of the matrix of piezoelectric sensor elements and a common reference net for the columns of the matrix of piezoelectric sensor elements, one of the isolated common reference nets is coupled to a signal reference bias voltage, and each row of the matrix of piezoelectric sensor elements is electrically coupled to the common reference net for the rows via a conditioning filter and each column of the matrix of piezoelectric sensor elements is electrically coupled to the common reference net for the columns via a conditioning filter. a matrix of piezoelectric sensor elements (11A - 11P) comprising rows of the piezoelectric sensor elements and columns of the piezoelectric sensor elements; measuring circuits (21A-21H, 31A-31H) configured to detect at least one touch, wherein the measuring circuits are configured to the rows and to the columns; and a wake-up trigger (14,143,145,33) configured to detect the at least one touch and further configured to trigger the matrix to an operation mode when the at least one touch is detected; characterized by the wake-up trigger is connected between the common reference net for the rows of the matrix of piezoelectric sensor elements and the common reference net for the columns of the matrix of piezoelectric sensor elements and the wake-up trigger is configured to monitor a voltage difference between the isolated common reference nets, wherein the wake-up trigger further comprises a switch 14) and a high ohmic resistor permanently coupling the two reference nets, wherein the switch is an isolation switch, which disconnects the two separate common reference nets (141, 142), so that the voltage difference between the two common reference nets can be detected and wherein the wake-up trigger is configured to connect and disconnect the isolated reference nets by the switch and accordingly turn the switch on for activating the matrix to the operation mode, wherein the measuring circuits comprise signal conditioning filters (21A-21H) and detection devices (31A-31H), the isolated common reference nets comprise a common reference net for the rows of the matrix of piezoelectric sensor elements and a common reference net for the columns of the matrix of piezoelectric sensor elements, one of the isolated common reference nets is coupled to a signal reference bias voltage, and each row of the matrix of piezoelectric sensor elements is electrically coupled to the common reference net for the rows via a conditioning filter and each column of the matrix of piezoelectric sensor elements is electrically coupled to the common reference net for the columns via a conditioning filter.