Flexible high-frequency microwave inductors and capacitors integrated on a polyethylene terephthalate substrate

This letter reports the realization of bendable inductors and capacitors integrated on a polyethylene terephthalate substrate that can operate at high microwave frequencies. A low-temperature fabrication process compatible with flexible thin-film transistors (TFTs) was developed. By employing bendable dielectric materials, spiral inductors and metal-insulator-metal capacitors with high quality factors and high resonance frequencies were demonstrated. The effects of mechanical bending on the performance of inductors and capacitors were also measured and analyzed. These demonstrations combined with previously demonstrated microwave TFTs will lead to flexible radio-frequency and microwave systems in the future.