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The trade-off between electrical conductivity and mechanical flexibility in fiber sensors impedes their widespread adoption. During sports activities, extensive exposure to body sweat leads to a decline in the electrical performance of the sensors. A multidimensional biomimetic superhydrophobic yarn sensor was prepared, utilizing polyurethane (PU) yarn as the core and dopamine-modified MXene as the sheath. This was achieved by drawing inspiration from the structure of the cerebral cortex to combine the unique plate-tile structure of Nepenthes. Its surface bionic microstructure was constructed to increase the number of conductive connection points, resulting in the plate tile structure and realizing the high sensitivity and ultrahigh hydrophobicity of the yarn sensor. The final yarn prepared exhibited low resistance (0.6 KΩ), high sensitivity (3397.6), and superhydrophobic characteristics (contact angle = 135.3°). Integrating conductive yarns with polyamide knit fabric, fabric sensors are designed to effectively detect minor muscle movements. This capability is essential for precise movement monitoring and ensuring prompt medical assistance for patients with severe injuries. This approach enhances the sensitivity of yarn-based stretch sensors by implementing a multistage bionic yarn structure. Additionally, it remains unaffected by sweat when integrated into athlete monitoring fabrics, thereby ensuring precise monitoring accuracy. [ABSTRACT FROM AUTHOR]

This study proposes the design of a hybrid reluctance-actuated fast steering mirror (HRAFSM) using Maxwell's electromagnetic normal stress principle. Strain gauges were attached to the flexible supports as sensors for measuring the rotation angles. According to Maxwell's stress tensor theory and the theory of vibration mechanics, we obtained the dynamic equation of the HRAFSM in the uniaxial direction to investigate the relationship between the input current and the output angle of the entire system. Further, we propose a control algorithm combining proportional-integral-derivative (PID) and adaptive inverse control (AIC) to achieve high-precision control. We established an experimental system for testing and validation of the control method. The experimental results showed that the designed HRAFSM can achieve the expected rotation angle of ±1.5 mrad, and revealed a linear relationship between the rotation angle of the two axes and their corresponding strain voltages. The effectiveness of the designed controller was verified, and the amplitude tracking errors of the x- and y-axes were 0.1% and 0.14%, respectively. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) has been extensively explored for various applications due to its low cost, simple preparation, and excellent physical and chemical properties. Compared to non-degradable polymers such as polyamide (PI), bio-based precursors offer immense advantages for more sustainable development. In this study, folate was innovatively proposed as the precursor for high-quality LIG synthesis, which was further used for the development of strain sensors and electrochemical catalysis. The folate-based LIG strain sensor demonstrated a broad operating range (0–12%), high sensitivity (with a gauge factor up to 361), exceptional stability, and reliability (exhibiting a consistent response over 10,000 repeated stretching cycles). Moreover, it exhibited precise detection capabilities for subtle deformations induced by human respiration, speech, swallowing, pulse beating, and joint movements. In terms of electrochemical catalysis, folate-based LIG demonstrated a remarkable enhancement in increasing the degradation rate of pollutants like Rhodamine B through the electro-Fenton process. The findings of this study suggest that LIG derived from folate processes shows huge promise for applications such as medical monitoring, micromotion recognition, and water pollutant remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of ordered arrangement of MXene in hydrogel on its conductivity of hydrogel was investigated in detail. • The gradient structure in synergy with the thermal sensitive MXene nanolayer contributed to the excellent actuation ability of the hydrogel. • The hydrogel was able to rival commercial electrodes to detect Pulse and ECG signals. Smart sensing and excellent actuation abilities of natural organisms have driven scientists to develop bionic soft-bodied robots. However, most conventional robots suffer from poor electrical conductivity, limiting their application in real-time sensing and actuation. Here, we report a novel strategy to enhance the electrical conductivity of hydrogels that integrated actuation and strain-sensing functions for bioinspired self-sensing soft actuators. Conductive hydrogels were synthesized in situ by copolymerizing MXene nanosheets with thermosensitive N -isopropylacrylamide and acrylamide under a direct current electric field. The resulting hydrogels exhibited high electrical conductivity (2.11 mS/cm), good sensitivity with a gauge factor of 4.79 and long-term stability. The developed hydrogels demonstrated remarkable capabilities in detecting human motions at subtle strains such as facial expressions and large strains such as knee bending. Additionally, the hydrogel electrode patch was capable of monitoring physiological signals. Furthermore, the developed hydrogel showed good thermally induced actuation effects when the temperature was higher than 30 °C. Overall, this work provided new insights for the design of sensory materials with integrated self-sensing and actuation capabilities, which would pave the way for the development of high-performance conductive soft materials for intelligent soft robots and automated machinery. [ABSTRACT FROM AUTHOR]

Because of the serious swelling issue and the lack of regular conductive channels, designing underwater sensors from conductive hydrogel (CHs) with high sensitivity remains challenging. Herein, an anisotropic conductive hydrogel (A-PCT-P) was obtained from polyvinyl alcohol (PVA), carbon nanotubes (CNTs), and tannic (TA) by a four-step strategy to address this issue. First, the PVA aqueous solutions were frozen-thawed to form precursor hydrogels crosslinked by crystalline regions. Next, the precursor hydrogels were pre-stretched at 60 °C to form regular conductive channels. Later, the pre-stretched hydrogels were frozen at refrigerator to fix the orientation structures. Finally, the dialysis process promoted the hydrogel to reach swelling equilibrium. Owing to the synergy of these strategies, the obtained hydrogel displayed excellent swelling-resistance. It barely expanded after immersing in deionized water with stable mechanical performances and volume. Meanwhile, the hydrogel-based sensor showed high sensitivity (gauge factor of 69.3), due to the CNTs and ordered structures. Remarkably, there was no baseline drift even after 1000 stretch-release repeats. All these advantages have promising applications in underwater sensing. [ABSTRACT FROM AUTHOR]

The effects of mechanical vibrations on control system stability could be significant in control systems designed on the assumption of rigid-body dynamics, such as launch vehicles. Vibrational loads can also cause damage to launch vehicles due to fatigue or excitation of structural resonances. This paper investigates a method to control structural vibrations in real time using a finite number of strain measurements from a fiber Bragg grating (FBG) sensor array. A scaled test article representative of the structural dynamics associated with an actual launch vehicle was designed and built. The main modal frequencies of the test specimen are extracted from finite element analysis. A model of the test article is developed, including frequency response, thruster dynamics, and sensor conversion matrices. A model-based robust controller is presented to minimize vibrations in the test article by using FBG measurements to calculate the required thrust in two cold gas actuators. Controller performance is validated both in simulation and on experiments with the proposed test article. The proposed controller achieves a 94% reduction in peak–peak vibration in the first mode, and 80% reduction in peak–peak vibration in the second mode, compared to the open loop response under continuously excited base motion. [ABSTRACT FROM AUTHOR]