Calibration-free, high-precision, and robust terahertz ultrafast metasurfaces for monitoring gastric cancers

Abstract

Optical sensors, with great potential to convert invisible bioanalytical response into readable information, have been envisioned as a powerful platform for biological analysis and early diagnosis of diseases. However, the current extraction of sensing data is basically processed via a series of complicated and time-consuming calibrations between samples and reference, which inevitably introduce extra measurement errors and potentially annihilate small intrinsic responses. Here, we have proposed and experimentally demonstrated a calibration-free sensor for achieving high-precision biosensing detection, based on an optically controlled terahertz (THz) ultrafast metasurface. Photoexcitation of the silicon bridge enables the resonant frequency shifting from 1.385 to 0.825 THz and reaches the maximal phase variation up to 50° at 1.11 THz. The typical environmental measurement errors are completely eliminated in theory by normalizing the Fourier-transformed transmission spectra between ultrashort time delays of 37 ps, resulting in an extremely robust sensing device for monitoring the cancerous process of gastric cells. We believe that our calibration-free sensors with high precision and robust advantages can extend their implementation to study ultrafast biological dynamics and may inspire considerable innovations in the field of medical devices with nondestructive detection.

Ultrafast Modulation of THz Waves Based on MoTe2-Covered Metasurface

“…The indirect band gap of MoTe 2 implies a possible application for near-infrared fiber communication located at the O-band (1260 nm–1360 nm) [ 58 ], enabling a hybrid control and ultrafast trigger of the infrared and THz waves. Furthermore, recent advances of the optically controlled THz metasurface have experimentally demonstrated a calibration-free sensor for achieving high-precision biosensing detection [ 31 ]. Since the biological interest concerns the full spectral range from THz wave to the mid-infrared (MIR) [ 59 , 60 ], the resonant frequency of the matasurface can also be extended to the MIR for more practical applications.…”

“…To solve this problem, the concept of reconfigurable metasurfaces comprised of the active media and meta-atoms has been proposed [ 25 , 26 , 27 ]. By introducing the external excitation such as the optical [ 28 , 29 , 30 , 31 , 32 , 33 ], electrical [ 34 , 35 , 36 ], thermal [ 37 , 38 , 39 ] and mechanical stimuli [ 40 , 41 ], the intrinsic properties or physical form of the active media can be changed, affecting the EM properties of the metasurface. For example, for the THz asymmetric split ring resonators (TASRs) covered by a 310-nm thick germanium (Ge) film, photogenerated carriers can be excited by the 800 nm pump laser stimulus to change the resonance state [ 32 ].…”

Identification and quantitative detection of two pathogenic bacteria based on a terahertz metasensor

“…33–36 Furthermore, the continuous optimization of the THz metasensors enables complex cell detection, including monitoring the carcinogenesis process of normal cells and discriminating the molecular typing of tumour cells, which is a major advance in the field of biosensing. 37–39 Arbitrary radiating metasurfaces can be analysed by an array of oscillating charge and loop currents, which involves the traditional concept of electric and magnetic multipoles, respectively. In recent years, the advent of a brand-new third family of electromagnetic multipoles, the toroidal dipole, has become equally important for the complete multipole analysis of metasurface radiation.…”

Terahertz refractive phenotype of living cells

“…With the rapid development of advanced optical techniques, the measurement of refractive index has been extended to a wider frequency range ( Zhuo et al, 2011 ; Liu et al, 2016 ). Compared with the visible region, the refractive index in the terahertz (THz) region is non-linear ( Baxter and Guglietta, 2011 ; Tcypkin et al, 2019 ; Novelli et al, 2020 ) and reveals the reorientation dynamics of water that hydrates the biomolecules ( Tros et al, 2017 ; Peng et al, 2021 ), which contains rich information closely related to the cellular activity and physiological status ( Yang et al, 2016a ; Ball, 2017 ; Liu et al, 2019 ; Zhang et al, 2021 ; Lou et al, 2022 ). Also intriguing is that THz wave does not cause ionizing damage making its more safe in biological measurements ( Olga et al, 2021 ; Liao et al, 2022 ).…”