Low-Cost Self-Driven Liquid Biosensor Based on Metamaterials for Glioblastoma-Related Sample Detection

A self-driven terahertz metamaterial liquid biosensor composed of channel-structured metamaterials and a quartz microcavity is proposed for glioblastoma sample detection. The device transports liquid samples via capillary force. The permittivity (ε_eff) of liquid suspensions is comprehensively analyzed to provide theoretical support for the detection. For suspensions with the same contents, ε_eff decreases with increasing concentration, while under the same concentration condition, ε_eff decreases as particle size grows. An electric dipole resonance is excited at ~1.54 THz with theoretical sensitivity ≥ 242 GHz/RIU (where RIU denotes refractive index unit). For the same type of cell discrimination, the frequencies of the biosensor's feature peaks shift from ~1.14, ~1.18, and ~1.20 THz with the rise in cell concentration of glioblastoma stem cell (GSC) suspension from 4 × 10⁵, 6 × 10⁵ to 8 × 10⁵ cells/mL, respectively. In addition, the GSC, U87 and U251-whose average diameters increase in that order-tested at the same concentration of 4 × 10⁵ cells/mL lead to feature peak shifts from ~1.14, ~1.17, and ~1.20 THz. Clear THz differences exist between healthy and patient serum, with peaks at 1.18 and 1.19 THz. The sensor effectively distinguishes cell suspensions but has limited serum discrimination capacity. The sensor retains cell morphology, requires little pretreatment, and is low-cost and fast for rapid glioblastoma clinical screening.