Metamaterial absorber integrated microfluidic terahertz sensors

Abstract

Spatial overlap between the electromagnetic fields and the analytes is a key factor for strong light-matter interaction leading to high sensitivity for label-free refractive index sensing. Usually, the overlap and therefore the sensitivity are limited by either the localized near field of plasmonic antennas or the decayed resonant mode outside the cavity applied to monitor the refractive index variation. In this paper, by constructing a metal microstructure array-dielectric-metal (MDM) structure, a novel metamaterial absorber integrated microfluidic sensor is proposed and demonstrated in terahertz (THz) range, where the dielectric layer of the MDM structure is hollow and acts as the microfluidic channel. Tuning the electromagnetic parameters of metamaterial absorber, greatly confined electromagnetic fields can be obtained in the channel resulting in significantly enhanced interaction between the analytes and the THz wave. A high sensitivity of 3.5 THz/RIU is predicted. The experimental results of devices working around 1 THz agree with the simulation ones well.The proposed idea to integrate metamaterial and microfluid with a large light-matter interaction can be extended to other frequency regions and has promising applications in matter detection and biosensing.2

Theoretical Investigation of a Simple Design of Triple-Band Terahertz Metamaterial Absorber for High-Q Sensing

“…Sensing performance of triple-band absorber (in terms of the surrounding refractive index, thickness and refractive index changes of the overlayer) is also analyzed. The results demonstrate that the FOM (figure of merit) of the third resonance peak can be up to 40.67, which is much larger than previously reported works [43][44][45][46][47][48][49][50], see Table 1. More importantly, we found that besides the frequency shifts with the change of the refractive indexes of the surrounding, the absorbance of the third resonance peak has an apparent change.…”

Terahertz spectroscopy in biomedical field: a review on signal-to-noise ratio improvement

“…In 2016, Hu et al constructed a metal microstructure array-dielectricmetal structure integrated with microfluidic. The sensitivity of their structure is 3.5 THz shifting per Refractive Units Index(THz/RIU) [33]. In 2017, Geng et al integrated two kinds of THz metamaterials biosensor with microfluidics as shown in Fig.…”

Terahertz Biochemical Molecule‐Specific Sensors

“…[85] Such microfluidic channels can sensitively capture the target samples only in an aqueous environment, avoiding huge signal loss by water absorption. [86][87][88] Combining the high-quality factor of resonators and microfluidic channels, several chemicals, biomarkers, or cells in a solution state could be detected. Another suggestion for improving the efficiency of a metamaterial sensing chip is to capture a specific molecule using the structure of a 2D thin film, such as graphene.…”