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Optical tweezer is a non-contact tool to trap and manipulate microparticles such as biological cells using coherent light beams. In this study, we utilized a dual-beam optical tweezer, created using two counterpropagating and slightly divergent laser beams to trap and deform biological cells. Human embryonic kidney 293 (HEK-293) and breast cancer (SKBR3) cells were used to characterize their membrane elasticity by optically stretching in the dual-beam optical tweezer. It was observed that the extent of deformation in both cell types increases with increasing optical trapping power. The SKBR3 cells exhibited greater percentage deformation than that of HEK-293 cells for a given trapping power. Our results demonstrate that the dual-beam optical tweezer provides measures of cell elasticity that can distinguish between various cell types. The non-contact optical cell stretching can be effectively utilized in disease diagnosis such as cancer based on the cell elasticity measures. 

Fabricating localized silicon-on-insulator (LSOI) on bulk silicon eliminates the need for using expensive SOI wafers for silicon waveguides and MEMS applications. One of the most important building blocks in silicon photonics is optical waveguide, which usually consists of silicon surrounded by silicon dioxide with refractive indices of 3.5 and 1.5, respectively. It was observed that the SOI wafer puts restrictions on the integration of electronics and photonics because the buried oxide is too thin for field confinement. Hence, fabrication of LSOI in standard silicon wafers is considered to have precise control of the oxide thickness which will lead to effective integration of electronic and photonic devices. We used rhombus-shaped channel method in the fabrication of LSOI structure that can be produced on any part of a bulk silicon wafer. 

Optical stretcher is a tool in which two counter-propagating, slightly diverging, and identical laser beams are used to trap and axially stretch microparticles in the path of light. In this work, we utilized the dual-beam optical stretcher setup to trap and stretch human embryonic kidney (HEK) cells and mammalian breast cancer (MBC) cells. Experiments were performed by exposing the HEK cells to counter-propagating laser beams for 30 seconds at powers ranging from 100 mW to 561 mW. It was observed that the percentage of cell deformation increased from 16.7% at 100 mW to 40.5% at 561 mW optical power. The MBC cells exhibited significantly higher cell stretching compared to HEK cells at the same power (80 mW). Moreover, the minimum trapping power in HEK cells was 80.5mW as compared to 65.2mW in MBC cells. This study provides useful insights into the characterization of cytoskeletal elasticity in different cell types based on non-contact optical cell stretching.