Design of a vanadium dioxide phase transition-based metamaterial absorption-sensing integrated device and its application in biological detection

To overcome two principal challenges in terahertz-band liquid biosensing—namely, the pronounced absorption of water and the limitation to single-function devices—we present the inaugural monolithic integration of vanadium dioxide (VO 2 ) phase-change tunability with an ultrathin (4 μ m) microfluidic channel within a unified axisymmetric metamaterial platform. This innovative design effectively bridges the existing divide between dynamic reconfigurability, previously confined to dry-air environments, and compatibility with liquid-phase biosensing. By modulating the insulator-to-metal transition of VO 2 , the device dynamically toggles between two high-performance operational modes: a broadband absorption mode exhibiting absorptivity exceeding 90% over the 1.26–3.05 THz frequency range, and a dual-band sensing mode characterized by near-perfect absorption (>98%) at 1.8 THz and 2.54 THz. The latter mode achieves refractive index sensitivities of 702 GHz RIU −1 and 978 GHz RIU −1 , substantially surpassing the sub-200 GHz RIU −1 sensitivity typical of conventional fixed-function microfluidic sensors. Computational simulations validate the device’s capability to reliably differentiate between normal and cancerous cells—including Jurkat, breast, basal, and cervical cell lines—through distinct frequency shifts ranging from 8 to 22 GHz, attributable to subtle refractive index variations of 0.012–0.024 refractive index unit. Furthermore, the axisymmetric configuration ensures polarization insensitivity and maintains stable performance for incident angles between 0° and 60°. This study delineates a viable pathway toward compact, dynamically tunable terahertz biosensing systems, with significant potential applications in early cancer detection and the development of integrated terahertz electronic devices.