A strain sensor is based on a self-biasing reference circuit that reaches an operating state that, at least at first order, is at least supply-voltage independent. The strain sensor provides an output signal that is defined by the operating state of the self-biasing reference circuit. At least one component in the self-biasing reference circuit has an electrical characteristic that depends on a strain to which the at least one component is subjected. This makes that the operating state of the self-biasing reference circuit depends on the strain. As a result, the output signal of the strain sensor varies as a function of the strain to which the at least one component is subjected.