Fig. 1. Schematic diagram of QBIC biosensor for lung cancer cell sensing.

Fig. 2. (a) Schematic of the unit cell. (b) Simulated spectra with g₁ varying from 8 to 26 µm. (c) The magnetic field distribution with the z-component in the xoy and xoz planes with g₁ = 24 µm, where the black arrows present the direction of the surface current. (d) Simulated spectrum of the structure with g₁ = 24 µm. (e) Calculated electromagnetic multipole scattering power.

Fig. 3. (a) Calculated band structure and (b) radiative Q-factors of the structure with g = g₁ = 8 µm. (c) The change of resonance frequency and Q-factor versus g₁. (d) Variation of Q-factor with asymmetric parameter δ.

Fig. 4. (a) Simulated and (b) measured spectra with different g₁, where the BIC is labeled by the yellow five-pointed star. (c) The simulated spectra with a series of refractive indexes n. (d) Calculated refractive index sensitivity of the biosensor. (e) Variation of refractive index sensitivity with structural scale factor. (f) Variation of the Q-factor with asymmetric parameters for scaling factors of 0.5, 1, and 1.5, where both axes are plotted on a logarithmic scale.

Fig. 5. (a) Schematic of the THz-TDS test system. (b) The microscopic image of the fabricated sensor. (c) Schematic of designed microfluidic liquid sample pool.

Fig. 6. (a) Microscopic images of sensors covered with different concentrations of living lung cancer cells. (b) Measured spectra of the sensor for different lung cancer cell concentrations and (c) the magnified view of resonance dips. (d) Variation trend of the resonance frequency and intensity with different cell concentrations. (e) Measured spectra of the bare sensor and the cleaned sensor after multiple measurements.