Fluorescent chemo-sensors based on “dually smart” optical micro/nano-waveguides lithographically fabricated with AIE composite resins

Abstract

Novel high-performance non-labeled fluoro-sensing micro/nano-optics require lithographically fabricable stimuli-fluorescence transductive materials well-tailored in molecular levels, towards superior processibility, stability, sensitivity, on-chip integration and portability, and real-time and in situ analysis. Here, aggregation-induced-emission fluorophores with oxetane groups (AIEoxes) and their covalently co-crosslinkable epoxy composites are customized for the fabrication of micro/nano-devices via single/multi-photon lithography. The oxetane modification increases the AIEoxe miscibility in the epoxy matrix (doping ratio up to 10 wt%), and consequently improves the as-formed devices’ quality, stability, and fluorescence intensity and sensitivity. The multi-color-AIEoxe polymeric micro/nano-devices allow fluorescence-resonance-energy-transfer among AIEoxes, which enables sensitive and specifically spectral detection of VOCs. With the micro/nano-waveguide configuration, solvent-responsive AIE fluorescence and evanescent-field/refractive-index sensing enhance the AIE-fluorescent detection of trace organic solvents in aqueous solutions (detection limit, ∼0.004% v/v, tetrahydrofuran/water) and their facile integration in functional micro/nano-systems like optofluidics.