Early detection of circulating tumor cells (CTCs) in a patient's blood is essential to accurate prognosis and effective cancer treatment monitoring. The methods used to detect and separate CTCs should have a high recovery rate and ensure cells viability for post-processing operations, such as cell culture and genetic analysis. In this paper, a novel dielectrophoresis (DEP)-based microfluidic system is presented for separating MDA-MB-231 cancer cells from various subtypes of WBCs with the practical cell viability approach. Three configurations for the sidewall electrodes are investigated to evaluate the separation performance. The simulation results based on the finite-element method show that semi-circular electrodes have the best performance with a recovery rate of nearly 95% under the same operational and geometric conditions. In this configuration, the maximum applied electric field (1.11 × 10⁵ V/m) to separate MDA-MB-231 is lower than the threshold value for cell electroporation. Also, the Joule heating study in this configuration shows that the cells are not damaged in the fluid temperature gradient (equal to 1 K). We hope that such a complete and step-by-step design is suitable to achieve DEP-based applicable cell separation biochips.

Graphene has originally low absorption at telecommunication wavelengths. Therefore it is necessary to overcome this hurdle to use graphene as absorption media in many optoelectronic devices. In this paper, a narrow-bandwidth graphenebased total absorber is numerically and theoretically investigated.The proposed structure consists of a graphene sheet on a Si rectangular grating, which is placed on SiO2 spacer backed with the gold substrate. Due to the absence of plasmonic response of graphene in near infrared wavelengths, the method of critical coupling with guided mode resonance is employed to realize highly efficient absorption of light in the graphene sheet. The simulation results show that the maximum magnitude of absorption reaches near 100% (43-fold enhancement compared to isolated monolayer graphene absorption of 2.3%). Also, based on calculated results, the absorption of the proposed structure can be controlled by altering the geometrical parameters and chemical potential of graphene. In particular, the absorption spectrum is modulated by the external gate voltage. Moreover, we find that the operating wavelength is adjusted flexibly by incident source angle. As a result, the proposed absorber has high directivity and can act similar to an antenna. The control ability of total absorption in the proposed structure provides potential applications for the realization of ultra-compact and high-performance optoelectronic devices, such as sensors and narrow-band filters.

In this study, a compact plasmonic structure for realising plasmon‐induced transparency is proposed and numerically investigated by using the finite‐difference time‐domain method. The suggested device consists of double side‐coupled square ring resonators based on a metal–insulator–metal platform. The coupled mode theory is introduced to describe the spectral response of the proposed structure, which is verified by numerical simulations. By changing the geometrical and material parameters such as outer side length and width of square ring resonators and metal collision frequency, the transmission characteristics can be easily tuned. The simulation results show that the proposed plasmonic system is used as a sensor by filling the insulator region with different refractive index. The sensitivity and figure of merit of this sensor are calculated, 806 nm/RIU and 66 RIU ^–1 , respectively. It is found that the slow light effect can appear in the proposed structure. By design optimisation, the maximum value of the group index is achieved close to 65. Meanwhile, the group index profile is obtained for different values of geometrical parameters like coupling aperture widths. The proposed structure provides a new way to utilise in nanosensor devices and slow light systems.