Red blood cell as tunable microlens
A suspended Red Blood Cell (RBC) can behave as an adaptive liquid-lens at nanoscale, with imaging capability and tunable focal-length. In fact, thanks to the intrinsic amazing elastic properties, RBC can swell up from disk volume of 90fL up to a sphere reaching 150fL, varying its focal-length from negative to positive values by triggering the osmolarity of the buffer. This permits to change a divergent RBC-lens in a convergent one, and to “see” objects that otherwise would be out-of-focus. But the most important application is in blood diagnostics: by exploiting the new concept of RBC-ensemble as a nanolens-array and in analogy to Indirect Adaptive Optics (IAO) testing tools, it is possible to discern between healthy and anomalous RBCs through focal spots analysis, thus providing a completely new, faster and much more objective diagnostic criterion.
L. Miccio, P. Memmolo, F. Merola, P.A. Netti, and P. Ferraro, “Red blood cell as an adaptive optofluidic microlens”, Nat. Comm. 6, p. 6502 (2015).
Light propagation through complex media
Information transmission through complex media is often not necessarily lost, but rather it becomes scrambled. In principle, there is hope to recover this information by undoing the effects of scattering. We take advantage of the intrinsic features of the holographic method to investigate the problem of information recovery in presence of scattering layers. These layers, in fact, produce an undesired scattered radiation that we can model as speckle noise. In the case of quasi-static environments, we cannot characterize the scattering layer’s transmission matrix, nevertheless they provide a diversity that can be fruitfully used by Digital Holography to reduce speckle. We showed, for example, how the natural cell movement can be exploited in a scattering microfluidic channel to improve the image quality or how the random walk of bacteria can reduce coherent noise.