Design of terahertz metal-dielectric-metal waveguide with microfluidic sensing stub

•We design a terahertz metal-dielectric-metal waveguide sensor with embedded microfluidic channel suitable for sensing the refractive index variations in liquid.•The transmission properties are described using transmission line model and numerically simulated using finite-difference time domain method.•The THz-MDM sensor has a theoretical value of the refractive index detection sensitivity at 0.457 THz/RIU for a 20μm×μm×24μmμmcross-section channel.

We design a terahertz (THz) metal-dielectric-metal (MDM) waveguide sensor with embedded microfluidic channel suitable for sensing the refractive index variations in liquid. The transmission properties are described using transmission line model (TLM) and numerically simulated using finite-difference time domain (FDTD) method. The sensing characteristics of the structure are systematically analyzed through the examination of the transmission spectrum. The results reveal a series of pronounced resonance peaks in the transmission spectrum, which has linear relationship with the refractive index variation of the material under investigation. For detecting the presence of various cancer cells flowing through the microfluidic channel, we designed and optimized the structural parameters of the THz-MDM sensor and achieved a theoretical value of the refractive index detection sensitivity as high as 0.457 THz/RIU for a 20 μm×μm×24 μmμmcross-section channel. This work shows great promise toward realizing a compact THz refractive index sensor with high sensitivity for identifying the signatures of biological samples in liquid.