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The sensitivity of Tunnel Magnetoresistance (TMR) sensors is characterized by significant temperature drift and poor sensitivity drift repeatability, which severely impairs measurement accuracy. Conventional temperature compensation techniques are often hindered by low compensation precision, inadequate real-time performance, and an inability to effectively address the issue of poor repeatability in temperature drift characteristics. To overcome these challenges, this paper introduces a novel method for suppressing temperature drift in TMR sensors. In this method, an alternating reference magnetic field is applied to TMR sensors, and the output amplitude at the frequency of the reference magnetic field is calculated to compensate the sensitivity temperature drift in real time. Temperature characteristic tests were conducted in a non-magnetic temperature test chamber, and the results revealed that the proposed method significantly reduced the TMR sensitivity drift coefficient from 985.39 ppm/°C to 59.08 ppm/°C. Additionally, the repeatability of sensitivity temperature characteristic curves was enhanced, with a reduction in root mean square error from 0.84 to 0.21. This approach effectively mitigates temperature-induced sensitivity drift without necessitating the use of a temperature sensor, and has the advantages of real-time performance and repeatability, providing a new approach for the high-precision temperature drift suppression of TMR. [ABSTRACT FROM AUTHOR]

To investigate the optical characteristics and sources of brown carbon (BrC) in North China, where the atmospheric aerosol loadings are high and have severe impacts on Earth's climate system, we collected fine aerosols (PM 2.5) at an urban site in Tianjin over a 1-year period. We measured the ultraviolet (UV) light absorption and excitation emission matrix (EEM) fluorescence of the water-soluble BrC (WSBrC) and the water-insoluble but methanol-soluble BrC (WI-MSBrC) in the PM 2.5 using a three-dimensional fluorescence spectrometer. The average light absorption efficiency of both WSBrC (Abs365, WSBrC) and WI-MSBrC (Abs365, WI-MSBrC) at 365 nm was found to be highest in winter (10.4 ± 6.76 and 10.0 ± 5.13 Mm-1 , respectively) and distinct from season to season. The averages of the fluorescence index (FI) and the biological index (BIX) of WSBrC were lower in summer than in the other seasons and opposite to that of the humification index (HIX), which implied that the secondary formation and further chemical processing of aerosols were more intensive during the summer period than in the other seasons. However, in winter, the higher HIX together with the higher FI and BIX of WI-MSBrC suggested that the BrC loading was mainly influenced by primary emissions from biomass burning and coal combustion. Based on the EEM, the types of fluorophores in WSBrC were divided into humic-like substances (HULIS), including low-oxygenated and high-oxygenated species and protein-like compounds (PLOM), though mostly PLOM in the WI-MSBrC. The direct radiation absorption by both WSBrC and WI-MSBrC in the range of 300–400 nm accounted for ∼ 40 % of that (SFEAbs , 4.97 ± 2.71 and 7.58 ± 5.75 Wg-1 , respectively) in the range 300–700 nm. [ABSTRACT FROM AUTHOR]

The perception of fish locomotion is important for understanding their adaptive behaviors and ethological characteristics. However, the main strategy used for extracting fish attitudes involves the use of a vision-based monitoring system, which is limited in its range of observation and cannot perform tracking for long times. Here, we report the use of a wearable tagging electronic device, referred to as an underwater vest, to capture the surrounding flow field disturbances triggered by swimming or momentary postural changes. All of these goals were achieved by integrating a pair of pseudocapacitive pressure-sensing units and a flexible circuit board. Notably, additional conditions, such as variable hydraulic pressures and minimal changes in fish posture, require high stability and sensitivity of the sensing units. Thus, hybrid hydrogel electrodes were developed through cross-linking MXene with holey-reduced graphene oxide nanosheets and further modification with 1-ethyl-3-methylimidazolium dicyanamide ionic liquids, which increased the interfacial capacitance and long-term interfacial activity of the MXene. Consequently, the sensing unit exhibited ultrahigh sensitivity (Smax~136,207 kPa−1) in an aquatic environment for 60 days and superior high-pressure resolution (10 Pa) within a wide working range of 1 MPa. Ultimately, an underwater vest integrated with such sensing units clearly distinguished and recorded fish locomotion. We believe that the designed device may open avenues in flow field monitoring and ocean current detection and provide new insights into the development of sensitive underwater tagging. [ABSTRACT FROM AUTHOR]

Long‐term access to undersea information is of critical importance for undersea sensing. However, the paramount challenge in marine wearable technology lies in achieving durable and stable adhesion, coupled with biocompatibility, for devices submerged in the saline conditions of the ocean. Here, a self‐healing, seawater‐resistant hydrogel is reported that exhibits robust adhesion to diverse biotic and abiotic surfaces. Remarkably, the presented hydrogel is augmented with octopus sucker‐inspired microstructures, a feature that markedly improves its capability of organism adhesion underwater. The hydrogel exhibits robust mechanical properties in water, with over 20‐fold elongation in a fully swollen state, and a mechanical healing efficiency exceeding 90% after healing for 30 min. The hydrogel is applied toward several representative undersea scenes. Specifically, the hydrogels equipped with flexible pressure sensors are reliably affixed to fish and turtles for sensing hydraulic pressure for more than 20 days, while the hydrogels featuring a compact camera are mounted on corals and crabs for constant monitoring of surroundings. Furthermore, the hydrogel is molded into a mesh structure for integrating multiple sensors, functioning as multi‐node marine wearable platforms. The underwater hydrogel, with its broad applicability, introduces an approach to real‐time undersea monitoring and non‐invasive marine life internet construction. [ABSTRACT FROM AUTHOR]