The efficient and reliable monitoring of acetic acid is significant to environmental protection and human healthcare. LaFeO3 is a potential sensing material for acetic acid with its good sensitivity and high plasticity. To further improve the sensing properties of LaFeO ₃ to meet the requirements of applications, we successfully utilized the facile electrospinning technique to fabricate a series of acetic acid-sensitive Ag-doped (0-5 mol%) LaFeO ₃ nanotubes. The systematic characterization shows that the appropriate content (4 mol%) of Ag doping can effectively ameliorate the material morphology to realize loose porous structures. Meanwhile, the sensitization effect of Ag and ameliorated morphology significantly enhance the gas sensing properties of LaFeO ₃ to acetic acid vapor. The optimal Ag-doped LaFeO ₃ (4 mol%) loose nanotubes-based gas sensor results in a detection limit of 0.5 ppm and 3.6-fold enhancement of the response to 100 ppm acetic acid compared with the pure LaFeO ₃ compact nanotubes at a low operating temperature (150°C). It also exhibits excellent selectivity to acetic acid and good long-term stability. Therefore, Ag-doped LaFeO ₃ can be regarded as a promising material for sensing acetic acid in practical applications. Finally, the mechanism of enhanced gas-sensing properties is discussed.

Nowadays, bioelectronic devices are evolving from rigid to flexible materials and substrates, among which thermally-drawn-fiber-based bioelectronics represent promising technologies thanks to their inherent flexibility and seamless integration of multi-functionalities. However, electrochemical sensing within fibers remains a poorly explored area, as it imposes new demands for material properties—both the electrochemical sensitivity and the thermomechanical compatibility with the fiber drawing process. Here, we designed and fabricated microelectrode fibers made of carbon nanotube (CNT)-based hybrid nanocomposites and further evaluated their detailed electrochemical sensing performances. Carbon-black-impregnated polyethylene (CB-CPE) was chosen as the base material, into which CNT was loaded homogeneously in a concentration range of 3.8 to 10 wt%. First, electrical impedance characterization of CNT nanocomposites showed a remarkable decrease of the resistance with the increase in CNT loading ratio, suggesting that CNTs notably increased the effective electrical current pathways inside the composites. In addition, the proof-of-principle performance of fiber-based microelectrodes was characterized for the detection of ferrocenemethanol (FcMeOH) and dopamine (DA), exhibiting an ultra-high sensitivity. Additionally, we further examined the long-term stability of such composite-based electrode in exposure to the aqueous environment, mimicking the in vivo or in vitro settings. Later, we functionalized the surface of the microelectrode fiber with ion-sensitive membranes (ISM) for the selective sensing of Na${}^{+}$ ions. The miniature fiber-based electrochemical sensor developed here holds great potential for standalone point-of-care sensing applications. In the future, taking full advantage of the thermal drawing process, the electrical, optical, chemical, and electrochemical modalities can be all integrated together within a thin strand of fiber. This single fiber can be useful for fundamental multi-mechanistic studies for biological applications and the weaved fibers can be further applied for daily health monitoring as functional textiles.