Development of low-cost optical detection systems for point-of-care infectious disease detection and monitoring in low-resource settings
Tkaczyk, Tomasz S
Doctor of Philosophy
Nearly half the world’s population lives below the global poverty line of $2.50 per day. This population is disproportionately affected by infectious diseases due to a lack of regular screenings and early detection and intervention. Optical diagnostics provide a highly sensitive and specific, low-cost method by which to improve access to disease screening and monitoring at the point of care in low-resource settings. Point of care settings range from a patient’s bedside to a hospital, and there is a need for instrumentation that may be used across the point of care setting spectrum. This work describes a platform of miniature fluorescence microscopes designed for use in resource-limited point of care settings ranging from rural communities to hospital laboratories. The prototype units of the platform described here are three miniature microscopes: 1) A monochromatic infinity-corrected 0.25 NA microscope that was used for optical readout of multiplexed bead-based bioassays. This prototype was validated with a commercially available assay reader (Luminex’s MAGPIX); 2) An achromatic 0.35 NA finite conjugate objective designed for three-part white blood cell differential counts in rural areas. This unit was validated against a commercially available benchtop hematology analyzer (Beckman Coulter Ac T diff2) and is currently in use in clinical trials at Lyndon B. Johnson General Hospital; and 3) A tunable 0.25 NA infinity-corrected fluorescence microscope designed for use with a variety multiplexed biological samples. The tunable system does not require manual adjustment by a trained user between emission wavelengths due to the addition of two low-cost, commercially available electrowetted lenses. It was validated by isolating green and red emission signal of blood stained with acridine orange. Each microscope prototype costs at least one order of magnitude less than its commercially available instrumentation counterpart. Additionally, the per-test cost for all devices is <$1.00 since the sample platform used for all three modules is a standard microscope slide with low cost reagents, not a specialized cartridge or cuvette. With the platform of low-cost, high-performance microscopes described in this work, it is possible for diagnostic tests to be performed without expensive equipment or highly-trained clinicians, thereby delivering testing access to low-resources settings.
microscopy; optics; point of care; global health