Demonstration of a simple approach for sub‐microliter fluorescence detection by structured PDMS cuvette with TiO 2 nanoparticle inclusion using 3D printing technology

Abstract With the increasing importance of portable sensing devices, one keeps seeking possible optimization to detect the lower concentration of target molecules with reduced reagents. Here presents a method to enhance fluorescence detection through a miniature cylindrical lens integrated into an engineered PDMS cuvette with a high refractive index embedded TiO 2 nanoparticles. 3D printing technique was used to develop the moulds where the custom cuvette is produced utilizing the imprinting method. LED transmitter and blue laser diode were used as the excitation light sources to verify the light and materials interactions. In all the experiments, the fluorescence detection system was set at 90° alignments without any filters. First, the square‐shaped cuvette resulted in more fluorescence detection compared to the circular one. Hence, different fluorophore holders with square shapes were designed to investigate the efficiency of the integrated lens and the TiO 2 nanoparticles inclusions. Overall, the customized cuvette with integrated lens and nanoparticles demonstrated the most significant signal enhancement that reached the lower detection limit as 10 n M /L in 1 μL detection volume. This structural and material‐modified cuvette can significantly enhance fluorescent detection at a sub‐microliter scale, allowing further device miniaturization, especially for micro and nano fluidic devices using optical detection.