Determination of blood origin using flexible graphene/ag/SEBS substrate combined with surface enhanced Raman spectroscopy

Blood species identification is crucial for forensic investigations. Surface-enhanced Raman scattering (SERS) offers promising advantages including rapid detection, non-destructive analysis, and high sensitivity, but faces challenges from direct metal-biomolecule interactions that can cause spectral interference and sample degradation. Here, we present a novel approach using graphene/Ag/Styrene Ethylene Butylene Styrene (SEBS) flexible SERS substrates for rapid and non-destructive blood species determination. The innovative “sandwich” structure features single-layer graphene (0.34 nm) positioned between silver nanoparticles and blood samples, effectively preventing direct metal-blood contact while maintaining the superior SERS enhancement. The flexible substrate demonstrates good performance including high detection sensitivity (the detection sensitivity of 4-Mercaptobenzoic Acid (4-MBA) is 10 −12  M), excellent storage stability (>30 days), and remarkable mechanical durability (>100 folding cycles). We collected 682 SERS spectra from five animal species and employed a convolutional neural network algorithm for classification, achieving the classification performance with 98.54% accuracy, 98.29% precision, and 98.38% recall. The flexible substrate enables rapid analysis and maintains the spectral integrity of archived samples for up to 31 days. This flexible graphene /Ag/SEBS platform has reliable capabilities and offers accurate new means for on-site forensic applications: non-destructive analysis, field portability, rapid results, and high accuracy.