ACS Applied Electronic Materials最新文献

An electrochemical sensor was developed in this study by utilizing a 1T SnS₂–Nb₂CT_x heterostructure nanocomposite modified carbon yarn (CY) electrode for detecting serotonin (5-HT) in human biofluids. Utilizing the enhanced electrochemical activity of the 1T phase of SnS₂, a nanocomposite was made with Nb₂CT_x MXene via a hydrothermal method. The nanohexagon architecture of SnS₂ provides a heterojunction with Nb₂CT_x MXene and enables a conductive electron transfer network, leading to improved sensing capabilities with an enhanced electrochemical response. A detailed study was conducted to elucidate the mechanism behind the heterostucture formation with the help of ultraviolet photoelectron spectroscopy (UPS) analysis. The 1T SnS₂–Nb₂CT_x nanocomposite provided effective active sites for enhancing its electrochemical performance by the presence of terraces and edges in the hexagonal structured 1T SnS₂ and by the inherent electrochemical property of Nb₂CT_x MXene. The fabricated 1T SnS₂–Nb₂CT_x nanocomposite based electrochemical sensor demonstrated a wide linear detection range of 1 to 100 μM for 5-HT, with a detection limit of 81 nM. In addition, the developed sensor demonstrated high selectivity, excellent repeatability, reproducibility, as well as good stability for 5-HT detection. The sensor was beneficially used to determine 5-HT levels in artificial samples of human serum, cerebrospinal fluid (CSF), interstitial fluid (ISF), and human sweat, confirming its practicality for real sample analysis. Finally, a “lab on a syringe” prototype model was developed by placing three thread electrodes on a commonly available syringe barrel, and it demonstrated promising capabilities for POC applications in next-generation healthcare.

Flexible electronic devices are increasingly in demand in the modern world. Among them, high-performance flexible sensors for the detection of vapors of industrially widespread propylene glycol (PG) are of interest. Herein, carbon nanotubes (CNTs) were grown using radio frequency (RF) magnetron sputtering and subsequently deposited by the electron beam deposition method onto a flexible sensor substrate. The sensor fabrication was complemented by introducing Fe₂O₃:ZnO nanograins and Pd catalyst particles onto the CNTs surface using RF and DC (direct current) sputtering techniques, respectively. The sensing materials were characterized by scanning electron (SEM) and transmission electron (TEM) microscopies and energy dispersive X-ray (EDX), electron energy-loss (EELS), X-ray diffraction (XRD), and Raman spectroscopies. The availability of CNTs and catalytic metal (Ni) was evident on the Si (100) substrate, revealing the hexagonal orientation of CNTs and the lattice interlayer spacing. The PGV (propylene glycol vapor) sensing behavior of the prepared sensor was investigated in detail using ultraviolet (UV) light combined with thermal heating in the range of 25–250 °C. The favorable sensitivities were registered at 150 °C with UV irradiation, where the sensor response values in the range 7–22 coincided with the PGV concentration range 1.5–60 ppm, respectively. The high performance of the sensor was confirmed with a short response (25 s) and recovery (87 s) times measured at a low detection limit concentration (1.5 ppm). The Fe₂O₃:ZnO/CNTs material embedded in the flexible polyimide substrate with high selectivity and response stability can be the best candidate for effective detection of PGV on any flexible surface.

Single monolayers (MLs) of transition metal dichalcogenides (TMDs) like molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) are promising semiconductors for next-generation logic devices, photodetectors, and light-emitting diodes. Applications require industry-relevant deposition techniques that form large monocrystalline TMD domains with low defect density. In this work, we study the growth of WS₂ by metal–organic chemical vapor deposition on c-plane sapphire substrates at different temperatures. We investigate the growth phenomena during the initial stages before ML formation and apply the obtained knowledge to design an optimized deposition process. High deposition temperatures (1000 °C) yield a high degree of in-plane crystal orientation but give rise to codeposition of WS₂ and tungsten, presumably due to the fast desorption of sulfur species. The preferred WS₂ domain orientation can be modulated by the process: WS₂ deposition at 850 °C followed by annealing of WS₂ crystals in H₂S at 1000 °C results mainly in step-edge guided domains, whereas crystal lattice-guided domains are predominant during subsequent deposition at 1000 °C. The optimized three-step process results in a preferential formation of 0 and 60° oriented domains in the closed WS₂ ML, with less than 2% of crystals with different orientations. These presented insights can be used to modulate and optimize the WS₂ structure further toward monocrystalline monolayers.

An encapsulated sandwich-structured flexible strain sensor with high sensitivity and simple repairability was prepared using a Sn–Bi alloy film as the sensitive layer. Conductive composite materials were prepared by combining graphene with Ecoflex, to completely encapsulate the sensitive layer. The resultant flexible strain sensor demonstrated a wide sensing range (50%), high sensitivity coefficient of 16323 (0 < ε < 3.84%) and 2125 (3.84% < ε < 50%), rapid response time (approximately 46 ms), and high durability (∼4800 stretch-release cycles before needing repair). The high sensitivity was attributed to the cracks generated in the Sn–Bi alloy film during the stretching process, and the EG (Ecoflex/graphene) layer maintained the conductive pathways under large strains, greatly expanding the sensing range. Furthermore, the EG layers on the outside surfaces provided robust protection for the Sn–Bi alloy film, endowing the sensor with water, dust, and friction resistance, which is needed in various daily life scenarios. After 6000 cycles of stretching and releasing, the accumulation of cracks in the Sn–Bi alloy film resulted in significant residual resistance. With the melting point of the Sn–Bi alloy film as low as 47 °C, a simple thermal pressing treatment was used to rapidly and efficiently restore the damaged Sn–Bi alloy film to its initial state. This work presents an effective approach for achieving both high sensitivity and a wide sensing range in strain sensors. The encapsulated sandwich structure design endows the sensor with repair capabilities and resistance to external environmental interference. The sensor demonstrates significant potentiality for applications in health monitoring, electronic skin, and wearable devices.

Natural plant-material-based memory devices have been in the spotlight due to their versatile applications ranging from nonvolatile memory to neuromorphic computations. Locally available plant Nymphaea nouchali, whose vernacular English name is water lily (WL), leaves were used to design a resistive memory device having configuration Au/WL/ITO. The device exhibited write-once-read-many (WORM) behavior with memory window (∼10²), device yield (∼55%), read endurance (8000 times), and data retention (∼500 s). With the incorporation of synthetic clay mineral Laponite along with WL in the active layer, the device (Au/WL+Laponite/ITO) exhibited reliable resistive random-access memory (RRAM) behavior in addition to WORM based on the measurement protocol. In the Laponite-based device, the device performances improved significantly with higher retention time (up to 10 years), larger memory window (10⁴), greater device yield (88%) and higher read endurance (10 000 times). The cycle-to-cycle variability of the RRAM device has also been studied. The conduction mechanism of these memory devices is dominated by space charge limited conduction, Schottky emission, and conducting filament formation. Apart from that, in order to investigate the neuromorphic properties, several preliminary rules like the learning and forgetting nature of the RRAM device (potentiation and depression) have also been studied. Moreover, the plasticity of the artificial synapse has been studied by varying the pulse width, pulse amplitude, and pulse interval. The results suggest that these biodegradable as well as eco-friendly devices provide a greater prospective toward the sustainable electronics with RRAM and WORM memory applications as well neuromorphic computation.