THz metamaterial microfluidic sensors, which can be utilized for the detection of small volume liquid specimen, have attracted much attention in biosensing applications. In this paper, we propose a novel microfluidic channel embedded terahertz metamaterial sensor, which employs split ring resonators (SRRs) and asymmetric two-gap SRRs for the detection of liquid samples. Unlike currently reported THz metamaterial microfluidic sensors utilizing microfluidic superstrate-metal-substrate structure, our approach combines the microfluidic superstrate with substrate, by designing micro-channels underneath the gap of the SRRs within the PDMS substrate. It could be easily fabricated by standard photolithography techniques. The simulated results show that the performance of the sensor is dependent on the spacing angle between two gaps, the orientation of the gaps, as well as the polarization of electric fields. Furthermore, maximum Q factors of 9.5 and 44 are achieved for dipole resonance, with corresponding FOM of 0.63 and 2.89 RIU-1 for transmission and reflection scenarios. Thus, this concept and method not only provides sensitive biosensing for liquid-based samples, but also can be applied to other metamaterial structures to further improve the sensitivity.

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