<< MEMS-Based PVA/PPy/MIP Polymeric- Nanofiber Sensor Fabricated by LIFT-OFF Process for Detection 2,4-Dinitrotoluene Vapor

Abstract

We designed a highly selective sensor to monitor 2,4-dinitrotoluene vapor. Sensor includes a microelectromechanical system (MEMS) based- polyvinyl alcohol nanofibers containing nanoparticles of polypyrrole and molecularly imprinted molecule that fabricated via lift-off process. Molecularly imprinted polymer nanoparticles were synthesized by polyvinyl alcohol as a functional polymer, glutaraldehyde as cross-linker and 2,4-dinitrotoluene as the template molecule. SEM, FT-IR and XRD techniques found properties of molecular template nanoparticles and synthesized polypyrrole. Results showed that 56 and 45 nm, respectively, were the typical particle size of synthesized polypyrrole and molecularly imprinted polymer nanoparticles. Sensor surface was deposited via the electrospinning technique by composite nanofibers like polyvinyl alcohol/polypyrrole/molecularly imprinted polymer. AFM analysis on MEMS surface showed that sensor surface area increased from approximately 300 nm (coating nanofiber) to approximately $3.5~\mu \text{m}$ (coating nano mat). Sensor was characterized by a dynamic set-up designed for the production of explosive vapors at a wide range of concentrations of the explosive vapor (10-1000 ppb). The limit of detection for the sensor was projected as 65 ppb. The developed MEMS sensor was measured at a steady 2,4-dinitrotoluene concentration in presence of vapor from other organic compounds. The developed sensor was highly sensitive and was highly selective against 2,4-dinitrotoluene.