Real-time lens-free visualization of strong light scattering by biogenic guanine platelets

Microscopic observation system without lens has a potential to realize ubiquitous sensing network detecting micro/nano biological hazards to modern society because the lens-free imaging device can provide an extremely compact microscope. In addition to in slico micro-mirrors, liquid injectable organic micro-mirrors should be found and utilized for achieving the ideal imaging device for micro/nano objects. This study demonstrates a high contrast lens-free image of the projection from a biogenic guanine platelet floating in water. The fish guanine platelet generated intense and high directional diffraction as well as regular reflection of incident light. The light projection from guanine platelet individually formed an intense platelet-shaped image in real-time on CMOS image sensor arrays. A dynamic projection movie of the guanine platelet, the size of which was approximately 20 ∼ 40 μm × 5 ∼ 10 μm × 100 nm in thickness, was obtained in a small aqueous droplet whose height was less than 2 mm. The developed new lens-free technology using biogenic tiny platelet has an ability to portably visualize movements of the micro/nano objects interacting with the platelet. The compact lens-free inspection can contribute to keep our society in safe.