Multi-Wavelength Superspectral Imaging of Trace Vape Aerosol Residues on Cotton Fabric

ABSTRACT: E-cigarette use may deposit vape aerosol residues on indoor textile surfaces, creating a potential but underexplored source of trace evidence in forensic environments. Detecting these residues visually is challenging because they are low contrast and may be distributed microscopically across porous substrates. This study assessed the capability of multi-wavelength superspectral imaging (SSI) to visualise trace vape aerosol residues on cotton fabric and identify illumination conditions that improve residue detectability. Cotton samples were exposed to controlled vape aerosol deposition over seven consecutive days, with one exposed sample collected daily and compared with an unexposed control. Samples were examined using SSI under multiple illumination wavelengths, followed by qualitative image-based assessment of residue visibility and contrast characteristics. Violet illumination (405–425 nm) produced the clearest contrast and most effective visualisation of residue features on the cotton surface. Temporal imaging showed a non-linear visibility pattern, with prominent features on Day 1, reduced detectability from Days 2 to 4, and increased visibility from Day 5 onwards. No comparable residue features were observed in control samples. These findings demonstrate the potential of multi-wavelength SSI as a non-destructive preliminary screening approach for visualising trace vape aerosol residues on textile substrates under controlled conditions.