Optical manipulation of single cells in femtosecond laser fabricated lab-on-chip

Current frontier of cellular biology is the manipulation, analysis and sorting of single cells. Populations of cells in culture and in organisms, although considered nominally identical, often present some heterogeneity whose analysis may unravel the complexity of many biological phenomena [1]. Optical stretching is a powerful technique to study the mechanical properties of single suspended cells by means of the application of optical forces [2]. Single cell analysis and sorting are powerful tools for the selection of a small group of cells of interest out of a wide and heterogeneous population, such as cells from resected tumors or in vitro cultures; the goal of such analysis being the diagnosis of pathological disorders or the separation of specific cells for further analysis. In recent years considerable effort has been devoted to the development of integrated and low-cost optofluidic devices able to handle single cells. Among the different microfabrication technologies, femtosecond laser micromachining (FLM) 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 [3].