 This paper proposes a new type of capillary valve called the valve which uses a 3D structure and a void area to prevent cross contamination when activating the valve. The valve is designed to eliminate any backflow into the valve and reduce the mixing and diffusion during the loading and trigger steps. The authors demonstrate its successful implementation in a capillary-driven circuit for the determination of benzodiazepine, showing a 40% increase in the fluorescence intensity compared to the conventional method.