Method and system of optical manipulation of micrometer-sized objects, which comprises the steps of placing a pattern (2) of a certain material on a surface (1), wherein said material is capable of sustaining surface plasmons; placing a solution (4) comprising micrometer-sized objects in contact with said surface (1) and said pattern (2); applying at least one optical beam (5) at a certain wavelength and with a certain incident angle (.PHI.) to said surface (1) for certain time interval, thereby creating surface plasmons forces at said surface (1), in such a way that said micrometer-sized objects are trapped by the pattern (2) in a stable and selective way. Optical trap and use thereof as a tool for optically driven lab-on-a-chip.