It is provided a sensor device comprising: a proximity sensor; a processor; a wireless communication module; and a memory. The memory stores instructions that, when executed by the processor, cause the sensor device to: receive a user input signal; determine when the received user input signal matches a signal template being associated with an event; store in the memory a record indicating an occurrence of the event associated with the user input signal; and transmit, once the wireless communication module is active, any stored records.