Microscope-integrated micromanipulator based on multiple VCSEL traps

The compactness of VCSELs (Vertical Cavity Surface Emitting Lasers) provides them the ability to meet the demands of current biochip technologies. In earlier research, optical trapping of live biological cells and microspheres based on VCSEL array has been realized in the form of parallel static traps on a translation stage. In microfluidic systems (lab-on-a-chip devices), the background flow introduces complexity and uncertainty in velocity and force analysis on target microparticles, making the capability of transporting biological objects without moving sample highly desirable. Moreover independently controllable traps offer more flexibility in microparticle manipulation. In this paper, a microscope-integrated VCSEL trapping system capable of independent control and batch processing of microparticles is devised and demonstrated. Optical design considerations for keeping stable trapping performance while multiplexing are addressed. Both a single optical trap and a trap array can be controlled independently by tilting mirror while their relative depth can be adjusted without power loses in optical system. In the micromanipulator, a single VCSEL trap serves as a collector and distributor, while a VCSEL array provides the carrier for synchronous processing and small range shift. Potential improvement based on two independently controlled VCSEL arrays is discussed and related applications are investigated.