Lysozyme coating stabilizes MXene for durable flexible strain sensors
Researchers used a lysozyme-based coating to improve the stability and conductivity of MXene, achieving reliable performance in flexible strain sensors for over 90 days.
The two-dimensional material Ti₃C₂Tₓ MXene is gaining attention for its potential in flexible conductive hydrogel sensors due to its excellent electrical conductivity and ease of processing. However, its rapid oxidative degradation in aqueous environments poses a significant challenge for its long-term use in practical applications. This instability necessitates a robust strategy for environmental protection and interfacial stabilization.
Researchers have developed an innovative solution to this problem by using lysozyme for interfacial stabilization. They utilized the tris(2-carboxyethyl)phosphine (TCEP)-induced phase transition of lysozyme to form a dense, protein amyloid-like aggregate, known as PTL, on the surfaces of Ti₃C₂Tₓ nanosheets. This process resulted in the creation of a composite material, PTL@Ti₃C₂Tₓ, which showed significant improvements in chemical stability and electrical performance.
The PTL@Ti₃C₂Tₓ composite demonstrated a high hydrogel conductivity of 94.5 mS cm⁻¹. To understand the stabilization mechanism, density functional theory (DFT) calculations were conducted.
The protective capabilities of the PTL coating were confirmed through various analytical techniques, including spectroscopic, elemental, and electrical analyses. These tests verified that the PTL layer provided substantial antioxidant protection to the MXene core, enhancing its chemical resilience. This advancement is crucial for moving MXene technology from laboratory research to practical, long-lasting wearable electronics.
To showcase the practical application of the stabilized MXene, researchers incorporated the PTL@Ti₃C₂Tₓ material into a PVA/cellulose nanofiber composite hydrogel sensor, referred to as PCPT. This composite sensor exhibited impressive mechanical properties suitable for flexible electronics, with a high fracture strain of 584%, a tensile strength of 1.60 MPa, and a toughness of 5.25 MJ m⁻³. Additionally, it maintained a gauge factor of 4.27, indicating reliable strain sensing capabilities.
A notable finding was the operational longevity of the device. The PCPT sensor, utilizing the PTL@Ti₃C₂Tₓ MXene, retained stable sensing functionality even after 90 days of storage. This performance significantly exceeded that of unmodified Ti₃C₂Tₓ counterparts, addressing the primary limitation of oxidative degradation and confirming the material’s long-term viability.
This research presents an effective and environmentally friendly strategy for enhancing the durability and service life of Ti₃C₂Tₓ in flexible electronics and wearable sensing applications. By using natural biopolymers like lysozyme to create a protective, conductive interface, the study paves the way for more reliable and sustainable next-generation flexible sensors.
Source: MXenes