Poster Y4 - Disposable Microfluidic Cartridge to Analyze Patient Samples at the Point of Care

Introduction: The COVID-19 pandemic demonstrated traditional laboratory tests are too slow in reporting disease states of individuals. For viruses such as SARS-CoV2 which have longer incubation periods, latency in results can further the spread of disease, so there is a strong need for fast and accurate results at the point of care. We developed a prototype diagnostic system that collects and processes biosamples from patients to determine the presence of viral diseases in about one hour. The system includes a sample collection tube, disposable microfluidic cartridge, reusable electronic device with integrated heater and fluorescence detection, and analysis software.

Materials and

Methods: The disposable microfluidic cartridge is made with an injection molded acrylic containing embedded reaction chambers and channels. The cartridge is laminated with adhesive covers, hydrophobic filters for vents, and silicone rubber for valves. Patient biosamples are collected in a sample collection tube and inserted into the microfluidic cartridge, which extracts viral nucleic acids through a silica matrix and mixes them with custom lyophilized reagents. Our assay implements loop-mediated isothermal amplification (LAMP), which is a nucleic acid amplification technique that operates at one temperature and fluoresces when target viral sequences are amplified. The cartridge is inserted into our electronic device which heats the processed samples, optically monitors their fluorescence in real time, and reports positive results when there is an exponential increase in fluorescence.

Results, Conclusions, and Discussions: The microfluidic cartridge was proven to extract nucleic acids from a variety of biosamples including saliva, cervical swabs stored in sample transport media, and skin lesion swabs. The overall system has been validated by correctly identifying positive results from over 20 patients with SARS-CoV2, HPV, or Mpox. The limit of detection with contrived samples was found to be 375 viral RNA copies/µL and 0.25 viral DNA cells/µL. These values represent the level of nucleic acids present in the sample input, so the amount retrieved and amplified in the reaction chambers is much less. The microfluidic cartridge design and assay are being optimized to lower the limits of detection. We are in the process of expanding our system to detect other diseases from a variety of patient biofluids. We design with low resource settings in mind to keep costs affordable and accessible to a wide range of people globally.

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