Femtosecond laser fabricated optofluidic device to mechanically discriminate between cells

In recent years, considerable effort has been devoted to the development of integrated and low-cost optofluidic devices able to study single cells properties. Such devices usually rely on microfluidic circuits that guarantee a controlled flow of the cells while optical radiation is often exploited to probe or manipulate the cells under test. Among the different microfabrication technologies, femtosecond laser micromachining is ideally suited for this purpose as it provides the integration of both microfluidic and optical functions on the same glass chip leading to monolithic, perfectly aligned, robust and portable optofluidic devices. Diseased cells such as cancer cells are known to have different deformability compared to their healthy counterparts. Such difference can also be used to distinguish between metastatic and non-metastatic cancer cells. An effective approach to quantify cell mechanical characteristics in-vitro is to force them through micro-fluidic constrictions. We have fabricated and demonstrated a multipurpose optofluidic chip that integrates sorting of single cells by optical forces and a deformability assay based on a passage through a constriction. This device allows us to distinguish between non-metastatic and metastatic cancer cells with a fast and reliable method, depending on the fluidic pressure needed to force cells through the constriction. Comparison with well-assessed optical stretching measurements demonstrates the high sensitivity of this approach, notwithstanding its inherent simplicity. Further validation of the devices is provided with different cell lines and by investigating the effect of specific drugs on tumorigenic and metastatic cells.