Stretchable and tunable quartered split-ring resonator (QSRR) using terahertz metamaterial

A quartered split-ring resonator (QSRR) on the polydimethylsiloxane (PDMS) substrate is presented in the terahertz (THz) spectrum range, which is composed of four 90 degrees arcs with metal bars at both ends. By stretching the PDMS substrate using electromechanical actuation mechanism, the consequent deformation will change the geometric structure of QSRR and then result in the change of resonance shift. PDMS-based QSRR shows a tuning range of more than 82 GHz in resonant frequency shift from 876.7 GHz to 958.7 GHz by changing the distance between two adjacent metal bars of QSRR. In both horizontal polarization (HP) and vertical polarization (VP) modes, the electromagnetic response of the QSRR device exhibits single resonance and the electric field distributions are concentrated on the metal bars of QSRR while the magnetic field distributions are along the four arcs of QSRR. When PDMS-based QSRR device is exposed to an environment with different refractive indices, it shows high linearity of resonant frequency shift and refractive index change and exhibits high sensitivity for refractive index sensing applications. The calculated sensitivity is 211 GHz/RIU and the Pearson correlation coefficient is approximately 0.997. This stretchable and tunable QSRR design is expected to be used in tunable filters, sensors, switches, and other THz-wave optoelectronics applications. Meanwhile, the characteristics of PDMS-based substrate can greatly broaden the application scenarios, such as wearable electronics, microfluidic devices, and bio-compatible sensors.