Nanofluidic terahertz metasensor for sensing in aqueous environment

Abstract

The terahertz spectral region has received tremendous attention for label free chemical and biological sensing, due to the presence of molecular fingerprints, low energy characteristics, and remote sensing capabilities. However, a major hindrance for the realization of a high performance terahertz bio-chemical sensor comes from the large absorption of terahertz waves by aqueous solution. Here, we overcome this limitation by confining the analyte-aqueous solution in a nanovolumetric fluidic chamber, integrated on metamaterial resonant cavities. The metamaterial resonators confine electromagnetic fields in extremely subwavelength space and hence allow for the enhanced interaction between the nanovolumetric analyte-aqueous solution and terahertz waves, while minimizing the absorption loss. We compare the sensing performance of split ring resonator and Fano resonator systems as metamaterial resonators. As a demonstration of chemical sensing, three alcoholic solutions with different concentrations were measured. Selective adenosine triphosphate (ATP) sensing capability was examined through ATP aptamer functionalization on gold metamaterials, where a decrease in the transmittance value was observed as the ATP concentration increased. The proposed sensing approach has the potential to be an effective tool for molecular analysis through exploiting the advantages offered by low energy terahertz, subwavelength metamaterial resonators and nanofluidic technologies.

Terahertz Microfluidic Metamaterial Biosensor for Sensitive Detection of Small-Volume Liquid Samples

“…The IPA-water mixtures with the IPA percent of 100%, 75%, 50%, 25% and 0% were tested (100%-pure IPA, 0%-pure water). The refractive index and the absorption coefficient of the IPA-water mixture decrease with the increase of the IPA concentration [22], [26]. For comparison, the IPA-water mixtures were also measured based on the MM with one big channel.…”

“…In the previous studies, the analyte is usually located in the whole area of the MM and the volume of the analyte is large [5][6][7][8][9][10][11][12][13][14][15][16][20][21][22][23][24][25][26][27]. If we don't consider the required sample volume, the resonance frequency shift per unit refractive index change in our study (72 GHz/RIU for the multichannel design, 223 GHz/RIU for the one big channel design) is comparable to previous studies (such as, 40 GHz/RIU [13], 220 GHz/RIU [20], 305 GHz/RIU [21]).…”

A Stretchable Terahertz Parabolic‐Shaped Metamaterial

“…It can be observed that the trend of the Q ‐factor at ω 1 shows a linear increase with a maximum value of 50. The abovementioned electromagnetic performance is better than that obtained for other THz‐metamaterial devices reported in the literature . This result can be explained by the field distributions for the PSM in the TE and TM modes, as shown in Figure c.…”

“…However, these approaches are limited to certain applications owing to symmetric or asymmetric split‐ring resonator configurations. Moreover, tunable THz metamaterials reported in the literature are limited to low Q ‐factors (≈0.5–5) and require complicated fabrication processes . Meanwhile, fabrication is mostly completed on Si, III–V materials, and quartz substrates, which strictly limits their possible applications, such as applications that have a requirement for a curved surface.…”

Leveraging of MEMS Technologies for Optical Metamaterials Applications

“…Therefore, the nanofluidic platform is developed for THz sensing in the aqueous environment. In Figure h, selective sensing of adenosine triphosphate (ATP) was demonstrated through aptamer functionalization on Au metallic metamaterial patterns, which allows in vivo monitoring of bioprocess in the aqueous environment …”