ACS Sensors最新文献

Total alkalinity (TA) is one of the measurable parameters that characterize the oceanic carbonate system. A high temporal and spatial frequency in TA data can lead to better measurements, modeling, and understanding of the carbon cycle in aquatic systems, providing insights into problems from global climate change to ecosystem functioning. However, there are very few autonomous technologies for in situ TA measurements, and none with field demonstrations below 2 m depth. To meet this need in marine observing capabilities, we present a submersible sensor for autonomous in situ TA measurements to full ocean depths. This sensor uses lab-on-a-chip technology to sample seawater and perform single-point open-cell titration with an optical measurement. It can carry multiple calibration materials on board, allowing for routine recalibration and quality checks in the field. The sensor was characterized in the laboratory and in a pressure testing facility to 600 bar (equivalent to 6 km depth) and deployed in a shallow estuary, on a lander at 120 m depth, and on an autonomous underwater vehicle. With a demonstrated precision and accuracy regularly better than 5 μmol kg^–1 in field deployments, this sensor has the potential to dramatically expand our ability to perform long-term autonomous measurements of the marine carbonate system.

Large-area, flexible pyroelectric sensors have received increasing attention in a range of applications including electronic skin, robotics, and military. However, existing flexible pyroelectric sensors struggle to achieve both high pyroelectric performance and excellent mechanical properties simultaneously. Here, we propose a universal island-bridge percolation structure inspired by the electric organ of the electric ray that can enable flexible nonpyroelectric substrates with excellent mechanical properties to generate a pyroelectric effect. The island-bridge percolation network structure made of pyroelectric particles (island) and carboxyl-functionalized multiwalled carbon nanotubes (bridge) achieved the transmission and superposition of the pyroelectric effect through the film polarization and percolation effect. The pyroelectric sensor based on the island-bridge percolation network structure not only inherits the pyroelectric properties of the pyroelectric particles but also inherits the excellent mechanical properties of the nonpyroelectric substrates. The flexible pyroelectric sensors fabricated from polydimethylsiloxane (PDMS) substrates exhibit a good pyroelectric effect and excellent mechanical reliability even under 30% tensile rate and 5,000 tensile–retraction cycles, and those made from polyimide (PI) substrates can serve as electronic skin for robots to detect heat sources and possess infrared sensing properties with a maximum distance of 8 cm. This study provides ideas to fabricate flexible pyroelectric sensors with highly flexible and high-performance properties.

Traditional conductive hydrogels have disadvantages for wearable sensors, such as poor electrical conductivity, weak mechanical properties, narrow application temperature range, and required external power supply, which limit their wide application. However, manufacturing hydrogel sensors with excellent mechanical properties and self-adhesive, temperature-resistant, and self-powered properties remains a challenge. Herein, chitin nanofiber-reinforced eutectogels (CAANF) with self-adhesive, self-healing, transparent, environment tolerant, and good mechanical properties were obtained via a simple one-pot method with the deep eutectic solvent (DES) system composed of acrylic acid, acrylamide, and choline chloride (ChCl). High-density hydrogen bond networks between CAANFs can act as strong cross-linking sites, conferring high stretchability (1680%) and elasticity. Moreover, high-density hydrogen bond networks with dynamic reversibility can provide excellent self-healing and adhesion abilities. Due to the unique properties of DES, CAANF eutectic gels also exhibit good ionic conductivity and environmental resistance, allowing the sensor to be applied over a wide temperature range (−30 to 60 °C). Additionally, CAANF-based self-powered flexible sensors can be used to detect human movement, monitor health status, and transmit signals for the encryption and decryption of information according to the Morse code. This work expands the scope of portable applications in the field of wearable electronic devices.

Pathogenic bacterial infections pose a significant threat to human life, health, and socioeconomic development, with those arising from Escherichia coli (E. coli) O157:H7 being particularly concerning. Herein, customized aggregation-induced emission luminogens (AIEgen)-based signaling tags (TPA-galactose) were combined with a microfluidic chip for the determination of E. coli O157:H7. TPA-galactose undergoes hydrolysis by the β-galactosidase, resulting in the formation of highly fluorescent TPA–OH with AIE characteristics. Phages covalently bound to the surface of magnetic beads specifically capture and lyse E. coli O157:H7, releasing endogenous β-galactosidase, and the fluorescence intensity of TPA–OH facilitates the determination of E. coli O157:H7. The microfluidic chip process achieves a sensitivity of 45 CFU/mL in 45 min, requiring no DNA extraction or amplification, utilizing minimal sample volume, and enabling accurate one-stop quantification of live E. coli O157:H7. This strategy enables the rapid on-site determination of E. coli O157:H7 in environmental, food, and clinical samples, significantly enhancing public health and safety.

Timely and accurate detection of H₂S is crucial for preventing serious health issues in both humans and livestock upon exposure. However, metal-oxide-based H₂S sensors often suffer from mediocre sensitivity, poor selectivity, or long response/recovery time. Here, an atomic Ru species-driven SnO₂-based sensor is fabricated to realize highly sensitive and selective detection of H₂S at the parts per billion level as low as 100 ppb. The sensor shows a high sensing response (R_air/R_gas = 310.1) and an ultrafast response time (less than 1 s) to 20 ppm H₂S at an operating temperature of 160 °C. Operando SR-FTIR spectroscopic characterizations and DFT calculations prove that the superior sensing properties can be mainly attributed to the driven effect of atomic Ru species on the formation of surface-adsorbed oxygen species on the surface of SnO₂, which provides more active sites and enhances the sensing performance of SnO₂ for H₂S. Furthermore, a lab-made wireless portable H₂S monitoring system is developed to rapidly detect the H₂S for early warning, suggesting the potential application of the fabricated H₂S sensor and monitoring system. This work provides a novel approach for fabricating a highly sensitive and selective gas sensor driven by atomic metal species loaded on metal-oxide semiconductors.