Fig. 1. Geometry of the EIT metamaterial sensor. (a) Metamaterial sensor array; (b) Schematic of the sensor unit;(c) Transmission spectrum of the sensor

Fig. 2. Flowchart of genetic algorithm (GA) for parameter optimization

Fig. 3. Transmission amplitude curves for three substructures. (a) UR; (b) MB; (c) CL

Fig. 4. Diagram of electric field distribution. (a) At four trough frequencies; (b) At three transmission peak frequencies

Fig. 5. Diagram of current distribution. (a) At four trough frequencies; (b) At three peak transmission frequencies

Fig. 6. Effect of analyte thickness hon sensing performance. (a) Fitted sensitivity analysis of f₁;(b) Fitted sensitivity analysis of f₂; (c) Fitted sensitivity analysis of f₃; (d) Effect of sample thickness on the sensitivity of three transmission peaks

Fig. 7. Schematic of substrate etching

Fig. 8. Effect of etch depth on sensing performance. (a) Transmission curves of the metamaterials under different etching depths;(b) Sensitivity variation of the sensor under different etching depths

Fig. 9. Electric field at f₃ frequency under different etching depths

Fig. 10. Transmission curves of the sensor under pesticide coverage. (a) Un-etched; (b) Etched