Abstract: A heating element includes a flexible substrate, a layer of adhesive disposed on a surface of the substrate, and a continuous strand of electrically conductive wire disposed on the adhesive in a pattern of coil structures. Each coil structure includes a first coiled part and a second coiled part. The wire in the first coiled part forms a counterclockwise pattern from an outermost turn to an innermost turn of the first coiled part, and the second coiled part has an innermost turn beginning at an end of the innermost turn of the first coiled part. The wire in the second coiled part forms a clockwise pattern from the innermost turn of the second coiled part to an outermost turn. A connector segment of wire connects outermost turns of adjacent ones of the coil structures.

Abstract: A method of attaching wire to an exposed surface of an adhesive layer includes guiding wire from a wire source through a payout head and through a foot of a write head. A first portion of the wire extends from the foot toward the adhesive layer. The write head is positioned such that a gap between the foot and the exposed surface of the adhesive layer is greater than a diameter of the wire. The write head is moved in a motion parallel to the adhesive layer, and the first portion of the wire adheres to the adhesive layer. Wire is pulled from the wire source by the payout head as the write head is moving in order to maintain slack in a second portion of the wire between the payout head and the write head as the wire is attached to the exposed surface of the adhesive layer.