Integration of Plano-Convex Lenses for Enhanced Fluorescent Signal in Centrifugal Microfluidic Systems

We present a method for enhancing fluorescence signals in centrifugal microfluidic systems by integrating a plano-convex lens into the optical path of a fluorescence detector, effectively focusing emitted light onto a single point. Two-dimensional computational simulations were first conducted to optimize the lens design and positioning, resulting in a 1.7-fold increase in ray collection efficiency compared to configurations without the lens. When the optimally designed plano-convex lens was incorporated into the three-dimensional detection chamber of an actual centrifugal microfluidic system, fluorescence intensities from fluorescein solutions increased by approximately 40–80-fold across most of the tested concentration range. Finally, we applied this strategy to enhance fluorescence signals generated by reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays targeting Influenza B virus, where the lens-integrated disc achieved approximately 60-fold higher fluorescence signals than the lens-free disc. These findings indicate that this strategy can substantially improve fluorescence detection sensitivity in assays employing similar optical configurations and detection principles.