Metallic mesh-based terahertz biosensing of single- and double-stranded DNA

Abstract

We report on a promising approach for the label-free analysis of DNA molecules with electromagnetic surface waves in the terahertz (THz) region. A metallic mesh with a polyvinylidene difluoride membrane is employed for THz transmission analysis. The metallic mesh with opening holes provides a sharp dip structure in a THz transmission spectrum, which is sensitive to a small change of the refractive index of a sample on the metallic mesh surface. The optical properties of a small amount of DNA molecules cannot be investigated by a free-space THz measurement because of the low absorption coefficients of such samples. However, metallic mesh-based THz measurement revealed the difference in optical properties between single- and double-stranded DNA molecules on the basis of refractive index, as estimated from a dip frequency shift of the metallic mesh. Therefore, our metallic-based THz technique provides a dramatically enhanced sensitivity, and demonstrates the potential of our approach of the analysis of biologically relevant DNA samples.

Biomedical Applications of Terahertz Spectroscopy and Imaging

“…For instance, utilizing resonant THz structures as sample carriers, nucleic acid hybridization can be probed with femtomolar sensitivity [12], which is comparable to fluorescence tagging methods. Metallic mesh structures have been applied to observe the different optical properties of ssDNA and dsDNA with dramatically enhanced sensitivity (microgram level) [13]. Moreover, narrow absorption features with a 10-GHz line width have been successfully observed for RNA samples suspended in buffer solution using a nanofluidic channel as the sample cell [14].…”

Continuous-wave terahertz field imaging based on photonics-based self-heterodyne electro-optic detection

“…Since terahertz (THz) waves in the range from 0.1 to 10 THz have been attracting a great deal of interest for use in applications, such as communications [7] and biomedicine [8], a field imaging technique in the THz range has become necessary. An electro-optic (EO) detection technique can be used for THz field imaging [9], because of its large detectable bandwidth and negligible perturbation compared to measurement techniques in which metallic antennas or waveguides are used as a probe [10].…”

Subwavelength InSb-based Slot wavguides for THz transport: concept and practical implementations

“…Therefore the THz technology is now receiving an extensive attention with great promises for wide applications such as material characterization15, study of electronic coherence of SCs16, biochemical sensing17 and highly integrated THz circuits (ITCs)18. Similar to IPCs, the development of ITCs leads to a new generation of fast, low-loss and on-chip subwavelength THz devices.…”