Micron-Sized Bioparticles Detection through Phase Analysis of Back-Scattering Signals from Optical Fiber Tweezers: An Exploratory Study

Optical Fiber Tweezers (OFT) can be used to study manifestations of light-matter interactions and deduce properties of micron-sized bioparticles trapped within its laser focal point. Our group has previously co-invented an innovative approach for this purpose based on advanced optical signal processing named iLoF-intelligent Lab on Fiber- with very relevant results revealing it is possible to create a variety of time and frequency magnitude features for label-free and non-invasive optical fiber sensing technologies. Nevertheless, phase spectra has been neglected in these photonics approaches. In this context, we present an exploratory study on informative content extraction from phase of OFT back-scattering signals. Furthermore, we analyze if these phase features provide better discriminative performance when compared spectrum magnitude ones previously used by the iLoF technology. The phase spectrum of back-scattering signals showed to retain patterns related to the intrinsic properties of each particle and the derived set of features proved to be robust to detect and discriminate from synthetic microparticles to highly similar cancer-derived mammalian cells, with better discriminative potential than their previous magnitude spectral counterparts. Such results introduce phase as a potential new domain to obtain discriminative light pattern features from OFT systems applied to micron-sized particles detection. The high sensitivity of the analyzed phase features to different micron-sized bioparticles, namely cancer-associated glycoforms, presents great potential for future applications in point-of-care diagnosis, such as detection and identification of molecules circulating in the blood or its derivatives with important clinical outcomes.