MXene in Sensor Applications: Types, Progress, and Prospects

 

Abstract

The emerging two-dimensional (2D) material, MXene, has attracted widespread attention from researchers across various disciplines due to its unique properties. In the field of sensors, MXene exhibits exceptional conductivity, a high specific surface area, and excellent hydrophilicity, making it an ideal platform for biosensor recognition elements. Additionally, its surface is rich in functional groups, allowing for versatile modifications tailored to specific application needs. The 2D planar structure of MXene offers advantages superior to those of bulk nanomaterials, making it highly suitable for the development of high-performance sensors.
This review discusses the latest advancements in MXene-based sensors, including stress-strain sensors, optical sensors, temperature sensors, humidity sensors, and biological signal marker sensors. The preparation methods, performance characteristics, and sensing mechanisms of each type are comprehensively reviewed. Furthermore, this article critically examines the challenges and future prospects for MXene-based sensor technologies.

Introduction

The advancement of flexible electronics and the widespread adoption of the Internet of Things (IoT) have unleashed significant potential for sensors across many sectors. Sensors have become indispensable in everyday life, finding applications in consumer electronics, human-computer interactions, augmented reality devices, and electronic skin technologies.
A sensor detects environmental changes and transmits interpretable signals to electronic devices for further processing. There are many types of sensors available today, including those for strain/stress, humidity, gas detection, light detection, and biomolecule detection. Among the various nanomaterials employed, two-dimensional layered materials such as MXene present distinct advantages.

MXene refers to a family of two-dimensional transition metal carbides or nitrides. Discovered in 2011, MXenes are typically represented by the chemical formula Mₙ₊₁XₙTₓ, where M is an early transition metal (e.g., Ti, Mo, or V), X is carbon or nitrogen, and Tₓ represents functional groups such as fluorine (-F), hydroxyl (-OH), and oxygen (-O). MXenes are produced by selectively etching the A-layer from MAX phase precursors.
MXenes possess outstanding properties, including excellent electrical conductivity, strong hydrophilicity, a large specific surface area, effective antibacterial properties, superior electromagnetic interference (EMI) shielding, and substantial energy storage capacity.

In the sensor field, traditional materials such as carbon and metal alloys are reaching their performance limits. Therefore, researchers are increasingly exploring MXene's potential across various sensor types, including chemical, biological, mechanical, and optical sensors. The high conductivity and large surface area of MXene align well with the critical requirements for sensing applications. Additionally, the 2D structure and abundant surface functional groups facilitate easy chemical modifications, enhancing MXene's suitability for advanced sensor technologies.

Despite its promising properties, challenges remain, including the need for enhanced stability, reproducibility, and multifunctionality to enable commercialization. Consequently, significant research efforts have been directed towards engineering novel MXene structures and developing advanced electrochemical strategies to improve sensor performance.
This review first examines MXene synthesis methods, intrinsic structure-property relationships, and surface modification techniques. It then categorizes MXene-based sensors by detection target — such as strain/pressure, temperature, gas, humidity, and biomarkers — and discusses their operating mechanisms and performance metrics. Finally, it outlines the future challenges and prospects in MXene-based sensor research.

MXene Synthesis

Since its discovery, MXenes have been extensively studied, with several types identified, including Ti₃C₂ and Ti₂C. Generally, MXenes are obtained by selectively etching the A-layer from MAX phases, layered materials characterized by alternating Mₙ₊₁Xₙ layers and A element layers.
The removal of the A element (commonly Al) exposes the M-X layers and results in a two-dimensional layered MXene structure. The exposed Ti atoms, for instance, connect with functional groups (-F, -OH, -O) introduced during the etching process, contributing to MXene’s hydrophilicity.
Because of these surface groups, MXene can disperse well in a variety of polar solvents, including water, propylene carbonate (PC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

Properties and Modification of MXene

The properties of MXenes largely depend on their structural composition, stacking degree, and dispersion state. Surface functionalization during synthesis or post-treatment significantly influences their sensing performance.
The hydrophilic surface groups facilitate dispersion, enhance chemical reactivity, and allow for further functionalization. These properties make MXenes particularly suitable for diverse sensing applications requiring high sensitivity and selectivity.

Applications in Sensors

Thanks to their exceptional physical, electrical, and chemical properties, MXenes have found extensive applications in sensor technology. Incorporating MXenes into sensors improves sensitivity and selectivity.
Moreover, MXenes exhibit good biocompatibility, allowing them to bind with biological receptors without disrupting biological activity.
An analysis of 463 research papers demonstrates the growing interest and applications of MXene-based sensors in areas such as pressure sensing, gas detection, humidity sensing, optical detection, and biosensing.

Conclusions and Perspectives

As a novel 2D material, MXene has attracted tremendous research attention for its unique properties. Significant advances have been made in synthesis techniques, surface modification strategies, and application development.
Sensors utilizing MXene fully leverage its two-dimensional characteristics, resulting in enhanced sensitivity, selectivity, and multifunctionality.
Nevertheless, challenges such as long-term stability, environmental durability, and scalable production must be addressed for broader commercial adoption. Future research is expected to focus on optimizing MXene structures, improving functionalization techniques, and integrating MXene sensors into complex electronic systems.