The global need for accurate and efficient cancer cell detection in biomedicine and clinical diagnosis has driven extensive research and technological development in the field. Precision, high-throughput, non-invasive separation, detection, and classification of individual cells are critical requirements for successful technology. Lab-on-a-chip devices offer enormous potential for solving biological and medical problems and have become a priority research area for microanalysis and manipulating cells. This paper reviews recent developments in the detection of cancer cells using the microfluidics-based lab-on-a-chip method, focusing on describing and explaining techniques that use optical phenomena and a plethora of probes for sensing, amplification, and immobilization. The paper describes how optics are applied in each experimental method, highlighting their advantages and disadvantages. The discussion includes a summary of current challenges and prospects for cancer diagnosis.

Surface plasmon (SP) response of nanoparticles (NP) has an unique path in the field of sensing, with specific developments in instrumentation and having a wide range of applications. Here it is described the light scattering process of NPs formed by magnetite core and gold shell (Au-Fe 3 O 4). Those were synthesized by the co-precipitation method, resulting in a quasi-spherical (icosahedral) shape of an average of 37.5 nm. It was found a plasmonic behaviour from UV-visible spectra, exhibiting a SP peak around 560 nm, this response is strongly dependent on NP size and shape. To describe its plasmonic response, it was employed the Rayleigh scattering and Mie theory for a metal-dielectric shell-core. The numerical solutions of these models confirms the SP response and that there is a correlation between the size and shape of NPs due to scattering of light from them.