A new two-axis micro coupler utilizing controllable moving wall and membrane structures for on-chip optical detection applications

Optical detection technique is critical for biomedical applications. The technique for optical fiber coupling is crucial for many optical detection applications. This study reports a new active two-axis micro coupler for buried optical fibers, which are commonly used for on-chip optical detection in microfluidic systems. The active micro coupler comprising air chambers, optical fiber channels, and controllable moving wall and membrane structures was fabricated by using micro electro-mechanical-systems technology. By adjusting air pressures to control the deflection of the pneumatic chambers placed orthogonal to and underneath optical fiber channels, precise alignment of buried head-on optical fibers can be achieved, which is crucial for on-line optical detection. Experimental results showed that the maximum deformation can be as high as 13 mum at an applied pressure of 40 psi for one air chamber, which is sufficient for precise coupling of two-axis optical fibers. The proposed device is promising for applications of head-on input/output fibers for the on-line optical analysis. It can be easily integrated with micro capillary electrophoresis or micro flow cytometer chips for DNA, protein and cell studies.