Disposable Porous Membranes to Enable Rapid and Inexpensive Nucleic Acid Amplification-Based Viral Diagnostic Toolkit at the Point of Need

FY21 PRMRP Topic Area Addressed by the Proposed Research: Emerging Viral Diseases. Emerging viral diseases contribute substantially to human morbidity and mortality, and thus they warrant an early and reliable diagnosis. Most people will suffer from superficial viral infection with mild to no symptoms, but millions of individuals globally will contract life-threatening viral infections that are much harder to contain (e.g., SARS-CoV-2). Unfortunately, accurate diagnosis of viral infections relies on highly technical molecular diagnostic assays such as the reverse transcriptase polymerase chain reaction (RT-PCR), which requires trained technicians operating multiple sophisticated and bulky instruments in well-equipped laboratories. The requirement of power-hungry thermal cyclers to repeatedly heat and cool the samples in PCR make it highly impractical for large-scale testing. We address this by combining the sample preparation and thermal cycling in one centrifugal platform without the requirement of any heaters. Instead, thermal cycling can be performed by converting the rotational kinetic energy of the spinning disc in a static magnetic field to thermal energy via eddy currents. This process is generally considered to generate waste energy but can be harnessed to actuate temperature-dependent biochemical reactions (like PCR) in small fluid volumes. For the proposed effort, we plan to determine the significant parameters that govern the eddy current heat generation in our custom lab on a disc platform with embedded metallic conductors and set of stationary magnets around the disc. Effects of magnetic strength, magnet orientation, and type of conductor will be studied to evaluate the interplay between the heat generated due to eddy currents and convective heat loss due to the high relative velocity of the air around the hot spots. Based on these results, we can find different operation speeds that maximize (i) heating and (ii) convective cooling in our system so that we can have both high heating and cooling ramp rates. Once our novel heating setup is optimized, we propose to integrate a porous sample preparation module in disposable disc chips to enable a "complete" nucleic acid amplification based diagnostic system. The resulting platform will be portable (< 1 lb), low powered (battery or hand powered), fast (sample to answer in < 40 minutes), user friendly (detection with smartphone camera and inbuilt app), and enable integrated sample preparation to detect emerging viral infections directly from clinical specimens at the point of need. Less