Real-time tunable terahertz sensors based on flexible single-walled carbon nanotubes

Abstract

Terahertz (THz) modulation plays a pivotal role in the advancement of THz devices. In recent years, with the continuous progress of science and technology and the deepening of research, a variety of effective approaches have been developed for THz wave modulation. Among these, THz modulation based on mechanical strain has become a feasible strategy. This method realizes THz modulation mainly through mechanical deformations such as stretching and bending, and is characterized by convenient operation and fast response. As an emerging carbon nanomaterial, carbon nanotubes (CNTs) possess favorable flexibility and tensile strength, making them highly suitable for the fabrication of mechanically tunable THz devices. Their stable chemical properties and excellent adsorption capacity also endow them with prominent advantages in the field of sensing and detection. In this work, we designed and fabricated a dual-frequency tunable THz sensing device based on single-walled CNTs (SWCNTs). The device is constructed with SWCNTs film and a Polydimethylsiloxane (PDMS) substrate, enabling THz wave modulation via mechanical strain. Experimental results show that the device achieves a maximum frequency modulation of 70 GHz under 10% tensile strain. Furthermore, sensing measurements are performed, and the device exhibits a limit of detection of 61.5 nM for benzoic acid. These results demonstrate that CNTs hold great application potential in the development of THz modulation and sensing devices.