Portable, low cost and sensitive cavity enhanced absorption (CEA) detection.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Biomedical Engineering

Background:

• Absorption spectroscopy offers broad applications but lacks sensitivity compared to techniques like fluorescence.
• Optical cavity approaches enhance absorption sensitivity by increasing light pathlength within a sample.
• Current optical cavity methods are not widely adopted for analytical or point-of-care applications.

Purpose of the Study:

• To develop a portable cavity enhanced absorption (CEA) spectrometer and a low-cost point-of-care (POC) reader.
• To demonstrate the utility of CEA for sensitive, wide dynamic range measurements.
• To enable low-cost, sensitive diagnostics, particularly for sepsis biomarkers.

Main Methods:

• Fabrication of a portable CEA spectrometer and POC reader using 3D printing.
• Utilizing single-pass and multi-pass cavity enhanced modes for measurements.
• Employing narrow band LEDs and photodiodes, omitting fiber optic coupling for cost reduction.
• Demonstrating immunoassay detection of C-Reactive Protein (CRP), Procalcitonin (PCT), and Interleukin 6 (IL-6).

Main Results:

• CEA mode increased pathlength 57.8-fold for Rhodamine B dye, achieving a limit of detection (LOD) of 7.1 × 10-11 M.
• The CEA POC reader demonstrated a 14-fold pathlength increase over conventional readers.
• Successful immunoassay detection of CRP, PCT, and IL-6 for potential sepsis diagnosis.

Conclusions:

• 3D-printed CEA spectrometers and POC readers offer a portable, cost-effective solution for sensitive absorption measurements.
• These CEA devices show significant potential for point-of-care diagnostics, including multi-biomarker panels for sepsis.
• Integration with wireless connectivity facilitates cloud-based data sharing for enhanced diagnostics.