Advancements in 2D-Ordered Linear Chain Carbon for Next-Generation Sensing Technologies

Low-dimensional carbon allotropes, such as carbyne, graphene, and carbon nanotubes, possess unique nanostructures and a wide array of physicochemical properties. They offer extensive functionality and have the potential to serve as fundamental building blocks in the development of hybrid carbon nano-systems and multifunctional composites. This enables the creation of materials with exceptional and distinct characteristics. Low-dimensional nanocarbons have great potential in driving the advancement of sensing technologies for the future. Carbyne, in particular, has garnered considerable attention due to its exceptional properties. It represents the epitome of one-dimensional carbon structures, with carbon atoms arranged in linear chains with sp-hybridization, showcasing carbon’s slender nature. Carbyne exhibits outstanding tensile strength, stiffness, and unique electrical properties attributed to the occurrence of alternating double and triple bonds along its chains. This extraordinary material is widely recognized for its exceptional strength, surpassing both diamond and graphene by a factor of two.

When a carbyne thread is stretched, its electrical properties undergo a remarkable transformation. It transitions from being conductive to becoming a dielectric form known as polyyne. This unique ability to toggle the conductivity of the carbyne thread presents fascinating opportunities. Moreover, the material’s optical absorption spectrum exhibits significant changes depending on the degree of tension applied, allowing for precise control over its sensitivity to various wavelengths of light. The remarkable mechanical and electronic properties of carbyne make it an outstanding material choice for ultrasensitive sensors and detectors in diverse applications. Unlocking the complete potential of carbyne presents an enthralling opportunity that has the potential to revolutionize chemical and biomolecular detection in fields such as healthcare and environmental monitoring. However, the instability and elevated reactivity of macroscopic carbyne crystals pose significant obstacles to their growth. To facilitate the practical implementation of carbyne-like nanostructures, achieving optimal stability for this unique form of carbon becomes crucial.

Recent progress in the field of carbon chain reactivity compensation has led to the emergence of an innovative form of carbon called “2D-ordered linear chain carbon.” This breakthrough technology enables the encapsulation of precisely aligned linear chains of carbon atoms, known as monatomic carbon filaments, within a matrix composed of amorphous carbon using ion-assisted pulse-plasma deposition. Employing this technique guarantees controlled growth of carbyne chains within a shielded environment. Additionally, the repulsive forces exerted by carbon chains impede the transition of carbyne into alternative carbon phases like graphite or diamond through van der Waals interactions. Due to its distinctive structural characteristics, this allotropic form is referred to as “2D-ordered linear chain carbon.”

The spatial arrangement of the nano-matrix, consisting of linear carbon chains arranged in a two-dimensional order, is composed of a hexagonal array distributed in two dimensions. These carbon chains are interconnected by van der Waals forces and are oriented perpendicular to the surface of the substrate. For example, the 2D-ordered linear-chain carbon offers a high surface area, providing numerous sites for molecule adsorption. Its electrical conductivity enables real-time electrical readout of binding events, while the stiffness and mechanical resonance of the carbon linear chains allow for highly sensitive mass detection in nanomechanical sensors. Moreover, the broad spectral absorption of carbyne can be adjusted based on strain, making it suitable for various optical sensing schemes. Furthermore, this nano-matrix exhibits a multicavity structure with empty functional nanocavities, presenting an opportunity for incorporating clusters of atoms from various chemical elements. These empty spaces can act as tiny cavities that aid in gas detection, expanding upon the concept of carbon nanotubes with new possibilities.

This particular nanomaterial possesses a comprehensive range of properties that make it highly compatible for accurately detecting particles and pollutants in both liquid and gaseous environments. The distinctive topological characteristics of 2D-ordered linear chain carbon have opened exciting avenues in the development of state-of-the-art nanosensor architectures, holding significant promise for advancements in high-tech applications.

Early findings have demonstrated the immense potential of 2D-ordered linear-chain carbon in revolutionizing the detection of gases, chemicals, and biological molecules. Its high surface area facilitates efficient molecule adsorption, and its exceptional electrical conductivity allows for real-time electrical readout of binding events. Additionally, its stiffness and mechanical resonance properties enable the creation of nanomechanical sensors with unparalleled sensitivity in mass detection. For example, the 2D-ordered linear-chain carbon into devices, these initial sensor demonstrations provide a glimpse into the transformative sensing capabilities that can be achieved with this material. To fully realize the potential of 2D-ordered linear chain carbon, Dr. Mariya Aleksandrova from the Technical University of Sofia, along with Dr. Alexander Lukin from the Western-Caucasus Research Center, explored its application in the development of advanced sensing technologies.

The team successfully developed nano-sensors utilizing the synthesized 2D-ordered linear chain carbon materials. Among these sensors were microcapacitor and surface acoustic wave (SAW) sensors specifically designed for the detection of volatile organic compounds, with a particular focus on ethanol vapor detection. They conducted a comprehensive evaluation of the sensors, considering sensitivity, response time, and the ability to detect varying concentrations of ethanol. The results revealed that the sensors exhibited different sensitivities to ethanol vapors based on the size and pattern of the membrane.

Sensors with smaller, meander-patterned membranes exhibited lower sensitivity at lower concentrations but displayed improved linearity and sensitivity at higher concentrations. On the other hand, larger, non-patterned membranes offered a wider dynamic range and better linearity, albeit with slower response times. Notably, the SAW sensors coated with carbyne-enriched films demonstrated promising results in detecting ethanol vapors, outperforming traditional sensing materials in terms of dynamic range, linearity, and sensitivity. An additional focus of the research was the optimization of sensor designs to enhance performance, particularly in terms of recovery time and the interaction mechanisms between the sensing layer and analytes. The findings highlighted the potential of these carbyne-based sensors in applications beyond ethanol vapor detection, spanning healthcare, environmental monitoring, and the detection of hazardous substances. It is important to acknowledge that further research is necessary to improve the scalability of synthesis and integration of these materials into practical devices. Nevertheless, the experimental work conducted by Drs. Aleksandrova and Lukin in the realm of 2D-ordered linear chain carbon presents a promising avenue for advancing sensing technologies. The development of sensors based on these materials holds the potential for enhanced sensitivity and versatility, enabling the detection of a wide range of chemical and biological substances with a high degree of precision. This opens up vast possibilities for applications in environmental monitoring, healthcare diagnostics, and the detection of hazardous substances.