Efficient metamaterial-based plasmonic sensors for micromixing evaluation

Recent developments in microscale flow mixing provide a promising alternative for lab-on-a-chip applications. However, accurate estimation of microscale mixing performance inside microfluidic channels remains a significant challenge. This process is limited by inevitable image aberrations and the distortion of microscopic imaging systems. In this study, we numerically present metamaterial-based optical sensors composed of periodic subwavelength H-shaped metallic resonators to evaluate the mixing efficiency of microfluidic mixers. Mixing performance was detected by exciting metamaterial sensors with near-infrared (NIR) light without additional optical couplers. Thus, the detection system was inexpensive and easy to operate. Notably, a large localized electromagnetic field up to 2 × 109 could be excited, whereas wavelengths of incident light matched the resonant conditions of metallic metamaterial arrays using the presented concept. The resulting figure of merit in terms of the detection sensitivity versus the full width at half maximum of the resonant peak reached a considerable value of 1.1. This study provides a promising detection method with sound sensing performance and the ability to be integrated with micromixing devices.