Photonically Encoded Silicone Lenses For Smartphone-Based Microscopy And Imaging In Biology And Nanomedicine

In this work [1], we describe the moldless preparation of a poly(dimethylsiloxane) (PDMS) lens embedding nanostructured porous silicon (PSi) optical components. Casting of uncured PDMS onto a PSi surface shapes a droplet with contact angle easily controllable by tuning of the nanostructure features (i.e., thickness and porosity of PSi). Design of the PSi layer as an optical component (e.g., distributed Bragg reflector, rugate filter, resonant cavity) allows the preparation of lightweight, freestanding PDMS lenses (10 mg mass and 4.7 mm focal length) with embedded optical elements. The fabrication process of the PDMS lens shows high reliability (yield >95%), low-cost (0.01 $), and good flexibility for a wide range of applications. For instance, using a single monolithic lens/filter element self-adhered to a commercial smartphone camera, we demonstrate: the fluorescence imaging and counting of live/dead isolated human cancer cells with high magnification and rejection of the excitation light; the selection of a narrow wavelength band from a fluorescent emission; and the tuning of the color of a white light emitting diode (from red to blue) through shaping of the emission spectrum.