Lens Fabrication by Accelerated Phase-Change for Mobile Multimodal Microscopic Imaging
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Smartphones have become a ubiquitous form of personal computing that incorporate powerful imaging sensors, computational processing power, mobility, power, and networking in one portable package. By incorporating an add-on lens to a smartphone camera, microscopic imaging can be made possible. We introduce a lens-making technique by using the accelerated phase-change of inkjet-printed polydimethylsiloxane which enable fabrication of microscope lenses with precise focal length control. The lens can be self-adhered onto smartphone cameras and result in an imaging resolution of 1 µm, sufficient for biological cell imaging. The optical power of the lens can be finely controlled by varying printing variables including volume and temperature to obtain the desired magnification, and we demonstrate the mathematical modeling required to obtain the correct focal length, as well as the equipment setup and procedures to print and quality check lenses in large batches of hundreds at a time. The limitations with smartphone imaging largely stems from its small sensor with lower signal-to-noise ratios than comparable scientific cameras, therefore imaging techniques that improve microscopic imaging quality, particularly in low-light levels are introduced. This method ensures images on a smartphone have comparable quality with scientific cameras. Furthermore, by using a 3D printer to create simple attachments and holders with appropriate light sources, multimodal microscopy can be achieved. These attachments include using bright-field for direct microbiological observations and slide imaging, dark-field for scattering imaging such as fingerprinting on transparent surfaces, and fluorescence microscopy for molecular identification either through autofluorescence or immunofluorescence. The simple yet powerful functions of this mobile multimodal microscope enhances the potential of using smartphones as a platform for point-of-care testing.