Ionogel Sensor for Reproducible Detection of Trace Methamphetamine Analogues
Drug detection is critical for public health and security, yet reversible and highly sensitive sensing materials remain scarce. This study presents a novel ionogel sensor material, poly(ethylene glycol) diacrylate (PEGDA)/1-butyl-3-methylimidazole tetrafluoroborate, for reproducible detection of N-methylphenylethylamine (MPEA), a structural analogue of methamphetamine. The ionogel is fabricated by immobilizing a flowable ionic liquid within a PEGDA network via UV curing, preserving ionic mobility for efficient conduction. Integrated on a flexible poly(ethylene naphthalate) substrate, the sensor exhibits over 72.6% transmittance in the visible spectrum, enabling concealed attachment. Utilizing non-covalent interactions, the sensor achieves reproducible MPEA detection at sub-ppb levels at room temperature, with a theoretical detection limit of 317 ppt. It demonstrates high selectivity and consistency. Ionic conductivity was confirmed via current-voltage tests and impedance spectroscopy, and the sensing mechanism was clarified. The device maintains reliable performance under bending, indicating suitability for dynamic environments. With Bluetooth integration for wireless data transmission, the sensor shows strong potential for practical, discreet drug monitoring in real-world applications.