Terahertz communication: detection and signal processing.

The development of 6 G networks has promoted related research based on terahertz communication. As submillimeter radiation, signal transportation via terahertz waves has several superior properties, including non-ionizing and easy penetration of non-metallic materials. This paper provides an overview of different terahertz detectors based on various mechanisms. Additionally, the detailed fabrication process, structural design, and the improvement strategies are summarized. Following that, it is essential and necessary to prevent the practical signal from noise, and methods such as wavelet transform, UM-MIMO and decoding have been introduced. This paper highlights the detection process of the terahertz wave system and signal processing after the collection of signal data.

An infrared photothermoelectric detector enabled by MXene and PEDOT:PSS composite for noncontact fingertip tracking.

Photothermoelectric (PTE) detectors functioning on the infrared spectrum show much potential for use in many fields, such as energy harvesting, nondestructive monitoring, and imaging fields. Recent advances in low-dimensional and semiconductor materials research have facilitated new opportunities for PTE detectors to be applied in material and structural design. However, these materials applied in PTE detectors face some challenges, such as unstable properties, high infrared reflection, and miniaturization issues. Herein, we report our fabrication of scalable bias-free PTE detectors based on Ti3C2 and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) composites and characterization of their composite morphology and broadband photoresponse. We also discuss various PTE engineering strategies, including substrate choices, electrode types, deposition methods, and vacuum conditions. Furthermore, we simulate metamaterials using different materials and hole sizes and fabricated a gold metamaterial with a bottom-up configuration by simultaneously combining MXene and polymer, which achieved an infrared photoresponse enhancement. Finally, we demonstrate a fingertip gesture response using the metamaterial-integrated PTE detector. This research proposes numerous implications of MXene and its related composites for wearable devices and Internet of Things (IoT) applications, such as the continuous biomedical tracking of human health conditions.

System design of large-area vertical photothermoelectric detectors based on carbon nanotube forests with MXene electrodes.

Photothermoelectric (PTE) detectors that combine photothermal and thermoelectric conversion have emerged in recent years. They can overcome bandgap limitations and achieve effective infrared detection. However, the development of PTE detectors and the related system design are in the early phases. Herein, we present vertical PTE detectors utilizing the active layer of carbon nanotube forests with MXenes acting as top electrodes. The detector demonstrates its capacity for sensitive infrared detection and rapid infrared response. We also investigated the relationship between photoresponse and different MXene electrode types as well as their thickness, which guides the PTE detector configuration design. Furthermore, we packed the PTE detectors with a polytetrafluoroethylene (PTFE, Teflon) cavity. The photoresponse is improved and the degradation is significantly delayed. We also applied this PTE detector system for non-destructive tracking (NDT) applications, where the photovoltage mapping pattern proves the viability of the imaging track. This work paves the way toward infrared energy harvesters and customized industrial NDT measurement.

The synergistic effect of Co/Ni in ultrathin metal-organic framework nanosheets for the prominent optimization of non-enzymatic electrochemical glucose detection.

Hybrid metal compounds have been paid increasing attention for the development of electroanalysis materials due to the specific collaboration interaction and synergy effect of metal elements. Herein, a series of ultrathin Ni/Co bimetallic metal-organic-framework nanosheets (UMOFNs) with different metal ratios were investigated as high-performance electroanalysis materials for non-enzymatic glucose electrochemical sensing. The synergistic effect between Ni/Co endowed UMOFNs with not only the unique electrochemical behavior that prompts the sensing-related electrochemical oxidation at a low applied potential, but also the enhanced affinity to glucose; also, they facilitated the electron transfer involving the analyte. The UMOFN composite with an elaborately adjusted Co/Ni ratio exhibits an extremely outstanding glucose sensing performance, including high sensitivity (2086.7 µA mM-1 cm-2), wide linear range (0.1 µM-1.4 mM), low detection limit (0.047 µM), and excellent selectivity. It can also be used for the detection of glucose in actual human serum samples with an accuracy of 90.1%, demonstrating a good application prospect of the non-enzymatic electrochemical glucose detection.