An electronic transducer comprises a knitted structure extendible in two dimensions defined by its courses and wales. An electro-conductive yarn (4) defines at least one single course in the structure adjacent non-conductive yarns (2), and is to be part of a circuit providing an indication of an electrical characteristic of the yarn. When unextended in either direction, successive loops of the stitches including the electro-conductive yarn are in engagement. Extension of the structure in the course direction separate loops forming the stitches, and extension in the wale direction urges the loops together. The structure can be used in methods of registering extension of the structure in either or both of the course and wale directions.