A man-machine interface comprises a sensor having first and second ends. The sensor carriers four transducers oriented there around such that the sensor is responsive to flex in two directions. An affixing mechanism, such as a glove or cloth strap, is provided for affixing the man-machine interface to a patient's body. A first mounting mechanism is provided for rigidly mounting the first end of the sensor to the affixing mechanism. A second mounting mechanism is provided for slidably mounting a second end of the sensor to the affixing mechanism. In that manner, flex in two directions can be sensed without adding any tensile forces to the sensor as a result of the joint being flexed.