A sensor arrangement for detecting muscle activity for the control of technical equipment. When in use the arrangement covers a region of the skin surface of a user, to provide a signal indicative of muscle activity in a limited region for subsequent processing. The arrangement has at least one double-differential myoelectric sensor, together with at least one near-infrared sensor. These are for simultaneous or time-delayed derivation of (a) myoelectric activity and (b) the value of a parameter of the blood (for example the blood oxygen content or the relative quantity of haemoglobin) respectively, in the muscle, the muscles or the tissue under the arrangement.
