Flexible devices incorporating electronically-conductive layers, including flexible wireless LC sensors

A method of producing a flexible structure that comprises a plurality of thin-film layers of elastomeric material and at least one layer of micro-wrinkled electrically conductive material, the method comprising:

• a) applying a selective anti-adhesion treatment process to a carrier substrate whereby an outer peripheral region of the substrate provides a strong adhesion region and the area of the substrate within the outer peripheral region provides an anti-adhesion central region;
• b) forming, on the carrier substrate, a first plurality of successive thin-film layers of PDMS, each of the successive thin-film layers of PDMS having a smaller ratio of crosslinking agent to base material and hence a higher Young's modulus than a preceding one of the thin-film layer of PDMS;
• c) forming, on the last-formed thin-film layer of PDMS, a first thin-film layer of Parylene;
• d) placing the carrier substrate in an organic solvent for a first period of time to induce swelling in the first plurality of thin-film layers of PDMS;
• e) forming, on the first thin-film layer of Parylene a first further thin-film layer of PDMS;
• f) forming by vacuum deposition, on the first further thin-film layer of PDMS, a second thin-film layer of Parylene in which a permanent micro-scale wrinkled surface morphology is generated as a consequence of diffusion of the organic solvent from the first plurality of thin-film layers of PDMS during said vacuum deposition, thus providing a first micro-scale wrinkled Parylene layer;
• g) forming and patterning a first layer of electrically conductive material on the first micro-scale wrinkled Parylene layer such that the first patterned electrically conductive material has a micro-scale wrinkled surface morphology conforming to that of the first micro-scale wrinkled Parylene layer, thus providing a first micro-scale wrinkled electrically conductive pattern layer.