STRaman Technology: Raman for See Through Material Identification

Significance of the topic

Raman spectroscopy is a key tool for chemical identification but conventional confocal designs fail when interrogating samples inside diffusely scattering media or when analyzing sensitive materials. The STRaman technology addresses these limitations by enabling through-barrier measurements with enhanced sampling depth, reduced power density and improved reproducibility.

Study objectives and overview

This work presents the See Through STRaman analyzer based on the i-Raman Pro ST platform. The objective is to demonstrate how expanded illumination and collection areas improve detection of chemicals within opaque packaging, coated forms and heterogeneous or photolabile samples, and to compare its performance with traditional and SORS approaches.

Methodology and instrumentation

• Instrument: i-Raman Pro ST spectrometer with 785 nm, 450 mW laser excitation and proprietary intensity correction.
• Optical design: large-area illumination and collection to increase sampling depth and reduce power density.
• Measurement configurations: STRaman for through-medium analysis and confocal mode via sampling kits (Focus Adaptor and Surface Regulator) for contact or microscopy measurements.
• Data processing: container subtraction algorithm (STID software) isolates content spectra from packaging signatures.

Key results and discussion

• Diffusely scattering plastics: Sodium benzoate in a white polyethylene bottle produced clear Raman features by STRaman, while conventional Raman was dominated by container signals. Subtraction yielded a spectrum matching pure sodium benzoate.
• Paper envelopes: D-(+) glucose was identified through a manila envelope with STRaman, whereas standard confocal measurement showed only cellulose features and fluorescence.
• Coated tablets: STRaman recovered the active ingredient spectrum from coated Advil tablets, in contrast to conventional Raman which was masked by sucrose coating.
• Sensitive and dark samples: Gun powder and biological tissue (human tibia and muscle) were measured with minimal heating; phosphate peaks in bone and biochemical markers in tissue were clearly resolved.
• Heterogeneous formulations: Excedrin® Migraine tablets measured with small spot size exhibited large spectral variation and identification failures, while STRaman’s several-millimeter sampling area provided consistent spectra (HQI > 99) and eliminated false negatives.
• Crystalline materials: Xylitol crystals showed orientation-dependent Raman variations in confocal mode; STRaman averaged over larger areas yielded highly reproducible spectra (HQI > 99.9) and no misidentifications.

Benefits and practical applications of the method

• Non-destructive chemical identification through opaque barriers (plastics, paper, coatings).
• Reduced sample damage and ability to analyze photolabile or thermolabile materials.
• Improved reproducibility for heterogeneous, crystalline and bulk samples.
• Versatile sampling via exchangeable adaptors for standoff, contact and microscopy Raman.
• Rapid, field-deployable analysis for QA/QC, materials inspection, pharmaceutical verification and security screening.

Future trends and potential applications

STRaman technology is poised to integrate with automated packaging lines, portable quality control platforms and advanced data analytics. Future developments may include miniaturized probes for endoscopic or standoff analysis, deeper integration with machine learning for substance classification and broader adoption in pharmaceutical manufacturing, food safety and biomedical diagnostics.

Conclusion

The See Through STRaman approach extends the utility of Raman spectroscopy by overcoming diffusion barriers, minimizing sample damage and enhancing reproducibility. Its high throughput design and adaptable sampling kits make it a powerful solution for complex analytical challenges across industry and research.

Reference

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