Portable smartphone-based fluorescent microscopes are becoming popular because of theircapability to carry out some of the major functionalities offered by regular benchtop microscopesat a fraction of the cost. However, these smartphone-based microscopes still have a lot oflimitations, such as being limited to only one fluorophore, unavailability of multiplemagnifications to name a few. To overcome these challenges, we present the design of a modularsmartphone-based microscopic attachment. Its

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... odular design allows the user to easily swapbetween different sets of filters and lenses, thereby providing the choice between multiplefluorophores and magnification levels. Furthermore, our proposed attachment can imagespecimens on glass slides, cover slips, and microfluidic devices. A 1951 USAF resolution testtarget was used to quantify the maximum resolution of the microscope which was found to be 3.9μm.The performance of the designed smartphone-based fluorescent microscope was then comparedwith regular benchtop microscope by counting fluorescent microparticles imaged. We found theperformance of our design to be satisfactory with an R2 value of 0.99. Additionally, to automatethe quantification of fluorescent microparticles, we developed and trained multiple artificial neuralnetworks (ANNs) using various training algorithms, and evaluated their performances comparedto the control (ImageJ) and found an R2 value of 0.99. We also performed ANOVA and Tukey'spost-hoc analysis and found a p-value=0.97 indicating no significant difference.As a potential application of the designed smartphone-based microscope, we also developed aPDMS based microfluidic chip to capture and quantify leukocytes from human blood. Anti-humanCD45 antibodies were functionalized inside the capture chamber of the microfluidic chip. Theseantibodies captured cells of interest based on antigen antibody interaction. These captured cellswere then made to fluoresce by using a green nuclear stain and the microfluidic chip was imagedunder the smartphone based fl [...]