Flexible triboelectric nanogenerators (TENGs) with multifunctional sensing capabilities offer an elegant solution to address the growing energy supply challenges for wearable smart electronics. Herein, a highly stretchable and durable electrode for wearable TENG is developed using ZIF‐8 as a reinforcing nanofiller in a hydrogel with LiCl electrolyte. ZIF‐8 nanocrystals improve the hydrogel's mechanical properties by forming hydrogen bonds with copolymer chains, resulting in 2.7 times greater stretchability than pure hydrogel. The hydrogel electrode is encapsulated by microstructured silicone layers that act as triboelectric materials and prevent water loss from the hydrogel. Optimized ZIF‐8‐based hydrogel electrodes enhance the output performance of TENG through the dynamic balance of electric double layers (EDLs) during contact electrification. Thus, the as‐fabricated TENG delivers an excellent power density of 3.47 Wm–2, which is 3.2 times higher than pure hydrogel‐based TENG. The developed TENG can scavenge biomechanical energy even at subzero temperatures to power small electronics and serve as excellent self‐powered pressure sensors for human‐machine interfaces (HMIs). The nanocomposite hydrogel‐based TENG can also function as a wearable biomotion sensor, detecting body movements with high sensitivity. This study demonstrates the significant potential of utilizing ZIF‐8 reinforced hydrogel as an electrode for wearable TENGs in energy harvesting and sensor technology.
The encapsulation of ZnQ into ZIF-8 allows fluorescent and colorimetric detection of nitroaromatic explosives, such as 2-4-6 trinitrotoluene (TNT). These are dangerous materials that pose safety and environmental risks.
This paper introduces a highly absorbent and sensitive cellulose nanofiber (CNF)/gold nanorod (GNR)@Ag surface-enhanced Raman scattering (SERS) sensor, fabricated using the vacuum filtration method. By optimizing the Ag thickness in the GNR@Ag core-shell structures and integrating them with CNFs, optimal SERS hotspots were identified using the Raman probe molecule 4-aminothiophenol (4-ATP). To concentrate pesticides extracted from fruit and vegetable surfaces, we utilized the evaporation enrichment effect using hydrophilic CNF and hole-punched hydrophobic polydimethylsiloxane (PDMS). This design leverages the hydrophilic substrate and localized evaporation to create a microfluidic flow that concentrates analytes within a small hole area, enhancing SERS sensitivity by up to 465 %. The sensor achieved on-site detection limits for Thiram as low as 10-11 M on fruit surfaces, specifically apples and chili peppers. This approach underscores how localized molecule enrichment can substantially improve field-based pesticide analysis. the sensor's response to interfering substances (e.g., glucose and citric acid) and other harmful molecules (e.g., carbendazim and nitrofurazone was also evaluated, demonstrating high sensitivity and accuracy). The PDMS-assisted CNF/GNR@Ag SERS sensor exhibits flexibility, ease of fabrication, and excellent sensitivity and selectivity, showing significant potential for applications in food safety, agriculture, and environmental monitoring. These advancements are anticipated to promote the practical adoption of SERS-based sensor technology across diverse fields, suggesting broad future utility.
Speciation of complex mixtures of trace explosives presents a formidable challenge for sensors that rely on chemoselective interfaces due to the unspecific nature of weak intermolecular interactions. Nanomechanical infrared (IR) spectroscopy provides higher selectivity in molecular detection without using chemoselective interfaces by measuring the photothermal effect of adsorbed molecules on a thermally sensitive microcantilever. In addition, unlike conventional IR spectroscopy, the detection sensitivity is drastically enhanced by increasing the IR laser power, since the photothermal signal comes from the absorption of IR photons and nonradiative decay processes. By using a broadly tunable quantum cascade laser for the resonant excitation of molecules, we increased the detection sensitivity by one order of magnitude compared to the use of a conventional IR monochromator. Here, we demonstrate the successful speciation and quantification of picogram levels of ternary mixtures of similar explosives (trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX), and pentaerythritol tetranitrate (PETN)) using nanomechanical IR spectroscopy.