Fully Inkjet-Printed VO2\n-Based Radio-Frequency Switches for Flexible Reconfigurable Components

Frequency-reconfigurable radio-frequency (RF) components are in high demand due to multiple frequency bands in wireless devices as well as varying frequency-spectrum standards across the world. An important part of reconfigurable components is a switch; however, existing switches are very expensive, particularly for higher frequencies (≈10s of dollars). In this regard, metal–insulator transition (MIT) materials are attractive, as they can change their phase and can be used as switches. Vanadium dioxide (VO2) is one such material that features a transition temperature of only 68 °C. The cost of the switch can be brought down considerably (≈cents) if MIT materials such as VO2 can be inkjet-printed; however, no ink of this sort is commercially available. In this work, VO2 ink and fully printed RF switches (shunt and series configurations) through this ink are presented for the first time. Both thermal and electrical triggering mechanisms are investigated in this work. These switches have shown decent performance up to 40 GHz. A more than 102 ON/OFF ratio and a switching speed of 0.4 µs are achieved. Finally, a frequency-reconfigurable antenna, printed on a flexible Kapton substrate along with a printed VO2 switch, is demonstrated as a proof of concept.