A safety device comprising: a pressure sensitive sensor having a plurality of first electrodes and a plurality of second electrodes , wherein each first electrode (46a-46h) overlaps each second electrode (48a-48e) in an associated coupling site and wherein each first electrode (46a-46h) in the associated coupling site is spaced apart from the associated second electrode by a pressure sensitive material , so that upon application of a force at the coupling site , an electrical resistance between the associated first electrode and the associated second electrode changes; a measuring circuitry coupled to said plurality of first electrodes and said plurality of second electrodes and configured to successively determine the electrical resistance at associated coupling sites ; and an evaluation unit configured to provide an output signal in response to the measured electrical resistances , wherein the measuring circuitry is configured, for determining the electrical resistance at a coupling site via the associated first electrode and the associated second electrode , to connect the further first electrodes and second electrodes to a terminal for receiving a defined potential to enable isolated measurement of the electrical resistance at the coupling site , wherein the evaluation unit is configured to determine the measured resistances from a measured voltage and to provide for each coupling site a first, second or third output signal in dependence on the measured voltage, and wherein the evaluation unit is configured to output the first output signal, when the measured voltage falls below a first threshold value or exceeds a second threshold value , to output the second signal, when said measured voltage exceeds said first threshold and falls below a third threshold lying between said first threshold and said second threshold , and output said third output, when said measured voltage exceeds said third threshold and falls below said second threshold . a pressure sensitive sensor having a plurality of first electrodes and a plurality of second electrodes , wherein each first electrode (46a-46h) overlaps each second electrode (48a-48e) in an associated coupling site and wherein each first electrode (46a-46h) in the associated coupling site is spaced apart from the associated second electrode by a pressure sensitive material , so that upon application of a force at the coupling site , an electrical resistance between the associated first electrode and the associated second electrode changes; a measuring circuitry coupled to said plurality of first electrodes and said plurality of second electrodes and configured to successively determine the electrical resistance at associated coupling sites ; and an evaluation unit configured to provide an output signal in response to the measured electrical resistances , wherein the measuring circuitry is configured, for determining the electrical resistance at a coupling site via the associated first electrode and the associated second electrode , to connect the further first electrodes and second electrodes to a terminal for receiving a defined potential to enable isolated measurement of the electrical resistance at the coupling site , wherein the evaluation unit is configured to determine the measured resistances from a measured voltage and to provide for each coupling site a first, second or third output signal in dependence on the measured voltage, and wherein the evaluation unit is configured to output the first output signal, when the measured voltage falls below a first threshold value or exceeds a second threshold value , to output the second signal, when said measured voltage exceeds said first threshold and falls below a third threshold lying between said first threshold and said second threshold , and output said third output, when said measured voltage exceeds said third threshold and falls below said second threshold . <EOS>