Substrate-integrated microfluidics for sensitive biosensing with complementary THz metamaterials in water

Abstract

Metamaterials can be utilized for a variety of applications and have emerged as a valuable tool in THz technologies. Used as THz biosensors, metasurfaces can significantly improve the sensitivity in the detection of biomolecules, but the high THz absorption of water represents a major challenge for the realization of a sensor for measurements in liquids. In this article, we propose an approach where the resonance feature of complementary asymmetric split ring resonators (CASRR) is maintained even for measurements in water, allowing highly sensitive detection of biomolecules in strongly absorbing liquids. This is enabled by the introduction of substrate-integrated microfluidics, which are shown to have a minimal effect on the transmission properties of the metamaterial. Due to this approach, the metamaterial structure design is independent from the microfluidic channels. Our simulations also show that the sensitivity of CASRR changes only marginally for lossless and highly absorbing materials. At the same time, the presented concept is easy to fabricate by standard lithography methods and can be applied to other metamaterial structures as well.