a safety system comprising an implant , a control device , and a machine . the machine has a control unit which is designed to allow operation of the machine only when a unique identifier has been received , and to set an operating mode of the machine as a function of the received suitability index . the implant is designed to detect physiological data of an implant wearer , and to either generate a suitability index based on detected physiological data and transmit the suitability index to the control device , or to transmit the physiological data itself to the control device .