A sensor device is provided for generating an electrical signal. The device includes an electrically conductive material having, at least in part, a three-dimensionally profiled surface. The surface is configured to create a change in said electrical signal in response to movement of a conductive object (e.g. a person's finger) thereacross. A method of using the sensor device includes connecting the sensor device to an electrical signal output device and moving an object across the three-dimensionally profiled surface to create a change in the electrical signal detectable by the electrical signal output device. A computer program is provided that is configured to, when executed, cause a computing device to perform the method. A system is provided that includes the sensor device and the computer program, the sensor device being electrically connectable to the computing device.