المؤلفون: Aono, Takanori¹ (AUTHOR) takanori.aono.wh@hitachi.com, Kanamaru, Masatoshi¹ (AUTHOR), Ikeda, Hiroshi¹ (AUTHOR)

المصدر: Electronics & Communications in Japan. Jun2024, Vol. 107 Issue 2, p1-7. 7p.

مصطلحات موضوعية: PRESSURE sensors, STRAIN sensors, DETECTORS, STAINLESS steel, WAFER level packaging

مستخلص: This research has developed a fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging (WLP) techniques. The thickness of sensor makes thinner, its performance is able to highly increase. However, the thinner sensor was fragile, and so it was difficult to handle in post processes. Thus, a thin sensor with lid by utilizing WLP techniques, which is tough to break even when handled, is proposed in this research. More than 250‐µm‐deep grooves were fabricated around the lid by deep reactive ion etching. After the lid substrate was bonded on the sensor substrate with a resin, the sensor and lid substrates were respectively polished to 50 and 200 µm thickness. The lids were released along the grooves, and the 50‐µm‐thick strain sensors were able to be fabricated by utilizing WLP techniques. This sensor was used as a diaphragm to measure pressure. The sensors were assembled on a stainless steel housing without breakage. The performance of the developed sensor was almost showed with a conventional pressure sensor. [ABSTRACT FROM AUTHOR]

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المؤلفون: Zhang, Zeyu¹ (AUTHOR), Li, Ziheng¹ (AUTHOR), Zhang, Mingxue¹ (AUTHOR), Hao, Hongshun¹ (AUTHOR), Yan, Shuang¹ (AUTHOR) yanye150@outlook.com

المصدر: Polymer Composites. 7/10/2024, Vol. 45 Issue 10, p8876-8888. 13p.

مصطلحات موضوعية: *STRAIN sensors, *COMPOSITE membranes (Chemistry), *POLYPYRROLE, *CARBON nanofibers, *CONDUCTING polymers, *WEARABLE technology

مستخلص: Carbon nanofibers have been widely studied as one of the promising materials for fabricating flexible electronic strain sensors. Surface modification of carbon nanofibers by conducting polymers is a simple yet effective approach to constructing strain sensors with good conductivity and sensitivity. In this work, composite nanofiber membranes composed of carbon nanofiber and conducting polymer are developed via in situ polymerization of pyrrole, aniline, and thiophene respectively on the surface of the carbon nanofiber which serves as a substrate. Different composite membranes, CNF@PANI, CNF/Ppy, and CNF@PTh, are successfully manufactured. The conducting polymer‐carbon nanofiber composite membranes exhibit improved conductivity as well as response sensitivity compared to pristine carbon nanofiber membranes. Among different composite membranes being studied, CNF/Ppy demonstrates the highest strain‐sensing performance. It shows good sensitivity, reproducibility, and stability in detecting both subtle (strain = 0.1%) and large (strain = 25%) deformation. The excellent strain‐sensing performance of CNF/Ppy endows the composite membrane with great potential for applications in wearable electronics. Highlights: Adding PANI, Ppy, and PTh could improve the conductivity of the CNF sensor.Ppy doping has a good effect on the performance of the CNF strain sensor.CNF/Ppy strain sensor has high sensitivity, stability, and durability.CNF/Ppy sensors can detect deformation caused by human movement.CP‐CNF composite material has good flexibility and mechanical properties. [ABSTRACT FROM AUTHOR]

المؤلفون: Chen, Si¹ (AUTHOR) 948542109@qq.com, Lv, Haoran¹ (AUTHOR) 806115954@qq.com, Zhao, Yinming² (AUTHOR) zhaoyinming@cimm.com.cn, Wang, Minning³ (AUTHOR) 1364574728@qq.com

المصدر: Sensor Review. 2024, Vol. 44 Issue 4, p405-413. 9p.

مصطلحات موضوعية: *STRAIN sensors, *ELASTOMERS, *DYNAMIC models, *DETECTORS

مستخلص: Purpose: This paper aims to provide a new method to study and improve the dynamic characteristics of the four-column resistance strain force sensor through the elastomer structure design and optimization. Design/methodology/approach: Based on the mechanism analysis method, the authors first present a dynamic characteristic model of the four-column resistance strain force sensors' elastomer. Then, the authors verified and modified the model according to the Solidworks finite element simulation results. Finally, the authors designed and optimized two types of four-column elastomers based on the dynamic characteristic model and verified the improvement of sensor dynamic performance through a hammer knock dynamic experiment. Findings: The Solidworks finite element simulation and hammer knock dynamic experiment results show that the relative error of the model is less than 10%, which confirms the accuracy of the model. The dynamic performance of the sensors based on the model can be improved by more than 30%, which is a great improvement in sensor dynamic performance. Originality/value: The authors first present a dynamic characteristic model of the four-column elastomer and optimize the four-column sensors successfully based on the mechanism analysis method. And a new method to study and improve the dynamic characteristics of the resistance is provided. [ABSTRACT FROM AUTHOR]

المؤلفون: Qi, Miao^1,2 (AUTHOR), Liu, Yanting³ (AUTHOR), Wang, Zhe⁴ (AUTHOR), Yuan, Shixing³ (AUTHOR), Li, Kaiwei⁴ (AUTHOR), Zhang, Qichong⁵ (AUTHOR), Chen, Mengxiao^1,2 (AUTHOR) mengxiaochen@zju.edu.cn, Wei, Lei³ (AUTHOR) wei.lei@ntu.edu.sg

المصدر: Advanced Science. 6/26/2024, Vol. 11 Issue 24, p1-11. 11p.

مصطلحات موضوعية: *SELF-healing materials, *STRAIN sensors, *DRAWING techniques, *DISTRIBUTED sensors, *SINGLE molecule magnets, *FIBERS

مستخلص: The development of soft electronics and soft fiber devices has significantly advanced flexible and wearable technology. However, they still face the risk of damage when exposed to sharp objects in real‐life applications. Taking inspiration from nature, self‐healable materials that can restore their physical properties after external damage offer a solution to this problem. Nevertheless, large‐scale production of self‐healable fibers is currently constrained. To address this limitation, this study leverages the thermal drawing technique to create elastic and stretchable self‐healable thermoplastic polyurethane (STPU) fibers, enabling cost‐effective mass production of such functional fibers. Furthermore, despite substantial research into the mechanisms of self‐healable materials, quantifying their healing speed and time poses a persistent challenge. Thus, transmission spectra are employed as a monitoring tool to observe the real‐time self‐healing process, facilitating an in‐depth investigation into the healing kinetics and efficiency. The versatility of the fabricated self‐healable fiber extends to its ability to be doped with a wide range of functional materials, including dye molecules and magnetic microparticles, which enables modular assembly to develop distributed strain sensors and soft actuators. These achievements highlight the potential applications of self‐healable fibers that seamlessly integrate with daily lives and open up new possibilities in various industries. [ABSTRACT FROM AUTHOR]

المؤلفون: Nankali, Mohammad¹, Amindehghan, Mohammad Amin^1,2, Seyed Alagheband, Seyed Hamed¹, Montazeri Shahtoori, Abdolsamad¹, Seethaler, Rudolf², Nouri, Nowrouz Mohammad¹ mnouri@iust.ac.ir, Milani, Abbas S.² abbas.milani@ubc.ca

المصدر: Advanced Materials Technologies. Jun2024, p1. 10p. 5 Illustrations.

مصطلحات موضوعية: *STRAIN sensors, *RAPID prototyping, *LASER ablation, *MASS production, *PLANT growth, *TOMATOES

مستخلص: The demand for stretchable strain sensors with customizable sensitivities has increased across a spectrum of applications, spanning from human motion detection to plant growth monitoring. Nevertheless, a major challenge remains in the digital fabrication of scalable and cost‐efficient strain sensors with tailored sensitivity to diverse demands. Currently, there is a lack of simple digital fabrication approaches capable of adjusting strain sensitivity in a controlled way with no changes to the material and without affecting the linearity. In this study, parallel microgates‐based strain sensors whose strain sensitivity can be adjusted systematically throughout an all‐laser‐based fabrication process without any material replacement are presented. The technique employs a two‐step direct laser writing method that combines the well‐established capabilities of laser ablation and laser marking, boasting a varying gauge factor of up to 433% (GF  =  168), while paving the way for the mass production of nanocomposite strain sensors. Parallel microgates‐based strain sensors exhibit a remarkable signal‐to‐noise ratio at ultralow strains (ɛ  =  0.001), rendering them ideal for monitoring the gradual growth of plants. As an application demonstration, the proposed sensors are deployed on tomato plants to capture their growth under varying planting conditions including hydroponic and soil mediums, as well as diverse irrigation regimens. [ABSTRACT FROM AUTHOR]

المؤلفون: Mei, Shunqi^1,2,3 (AUTHOR) sqmei@wtu.edu.cn, Xu, Bin¹ (AUTHOR) 13061159209@163.com, Wan, Jitao¹ (AUTHOR) 13636062780@163.com, Chen, Jia¹ (AUTHOR)

المصدر: Sensors (14248220). Jun2024, Vol. 24 Issue 12, p4026. 19p.

مصطلحات موضوعية: *STRAIN sensors, *ELBOW joint, *CHEST (Anatomy), *CARBON nanofibers, *CARBON nanotubes, *ELECTRIC conductivity, *WRIST

مستخلص: Flexible conductive films are a key component of strain sensors, and their performance directly affects the overall quality of the sensor. However, existing flexible conductive films struggle to maintain high conductivity while simultaneously ensuring excellent flexibility, hydrophobicity, and corrosion resistance, thereby limiting their use in harsh environments. In this paper, a novel method is proposed to fabricate flexible conductive films via centrifugal spinning to generate thermoplastic polyurethane (TPU) nanofiber substrates by employing carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as conductive fillers. These fillers are anchored to the nanofibers through ultrasonic dispersion and impregnation techniques and subsequently modified with polydimethylsiloxane (PDMS). This study focuses on the effect of different ratios of CNTs to CNFs on the film properties. Research demonstrated that at a 1:1 ratio of CNTs to CNFs, with TPU at a 20% concentration and PDMS solution at 2 wt%, the conductive films crafted from these blended fillers exhibited outstanding performance, characterized by electrical conductivity (31.4 S/m), elongation at break (217.5%), and tensile cycling stability (800 cycles at 20% strain). Furthermore, the nanofiber-based conductive films were tested by attaching them to various human body parts. The tests demonstrated that these films effectively respond to motion changes at the wrist, elbow joints, and chest cavity, underscoring their potential as core components in strain sensors. [ABSTRACT FROM AUTHOR]

المؤلفون: Zhang, Haifeng¹ (AUTHOR), Song, Qingyuan¹ (AUTHOR), Deng, Zejiang¹ (AUTHOR), Ren, Jie¹ (AUTHOR), Xiang, Xu¹ (AUTHOR) xxiang1984@cqjtu.edu.cn

المصدر: Polymer Bulletin. Jun2024, Vol. 81 Issue 9, p8045-8056. 12p.

مصطلحات موضوعية: *GUAR gum, *STRAIN sensors, *HYDROGELS, *SODIUM alginate, *FOURIER transform infrared spectroscopy

مستخلص: Hydrogel is a research hotspot in the field of polymer materials and has great application value in many fields, such as wearable devices. However, the mechanical properties of hydrogel limit its application range. As a natural biopolymer, sodium alginate (SA) has good biocompatibility, but SA hydrogels lack toughness and cannot meet the requirements of strain sensors. In this work, guar gum (GG) is used to enhance the toughness of SA hydrogels so that it can be used to prepare wearable devices. Scanning electron microscopy was used for morphological and structural studies, and Fourier transform infrared spectroscopy was used for cross-linking characterization. The results show that the SA/GG hydrogels prepared by the one-pot method have good tensile properties, and the wearable devices assembled based on them have good stimulus responsiveness, long-term operational stability and excellent water retention. Among them, the SA/GG-2 composite hydrogel has the most excellent comprehensive performance, with the maximum stress and strain reaching 36.5 kPa and 7.3%, and the water retention of the assembled sensors reaching more than 98%, and the resistance and capacitance change rate reaching more than 25%. The SA/GG composite hydrogel has a potential application prospect in the field of wearable devices. [ABSTRACT FROM AUTHOR]

المؤلفون: Shukla, Prashant¹ (AUTHOR) drprashantdb1980@gmail.com, Saxena, Pooja² (AUTHOR), Madhwal, Devinder¹ (AUTHOR), Singh, Yugal¹ (AUTHOR), Bhardwaj, Nitin¹ (AUTHOR), Samal, Rajesh¹ (AUTHOR), Kumar, Vivek¹ (AUTHOR), Jain, V. K.¹ (AUTHOR)

المصدر: Microchimica Acta. Jun2024, Vol. 191 Issue 6, p1-14. 14p.

مصطلحات موضوعية: *STRAIN sensors, *RANGE of motion of joints, *HUMAN body, *CONDUCTIVE ink, *ELECTRONIC equipment, *GRAPHITE oxide, *GRAPHITE

مستخلص: In the era of wearable electronic devices, which are quite popular nowadays, our research is focused on flexible as well as stretchable strain sensors, which are gaining humongous popularity because of recent advances in nanocomposites and their microstructures. Sensors that are stretchable and flexible based on graphene can be a prospective 'gateway' over the considerable biomedical speciality. The scientific community still faces a great problem in developing versatile and user-friendly graphene-based wearable strain sensors that satisfy the prerequisites of susceptible, ample range of sensing, and recoverable structural deformations. In this paper, we report the fabrication, development, detailed experimental analysis and electronic interfacing of a robust but simple PDMS/graphene/PDMS (PGP) multilayer strain sensor by drop casting conductive graphene ink as the sensing material onto a PDMS substrate. Electrochemical exfoliation of graphite leads to the production of abundant, fast and economical graphene. The PGP sensor selective to strain has a broad strain range of ⁓60%, with a maximum gauge factor of 850, detection of human physiological motion and personalized health monitoring, and the versatility to detect stretching with great sensitivity, recovery and repeatability. Additionally, recoverable structural deformation is demonstrated by the PGP strain sensors, and the sensor response is quite rapid for various ranges of frequency disturbances. The structural designation of graphene's overlap and crack structure is responsible for the resistance variations that give rise to the remarkable strain detection properties of this sensor. The comprehensive detection of resistance change resulting from different human body joints and physiological movements demonstrates that the PGP strain sensor is an effective choice for advanced biomedical and therapeutic electronic device utility. [ABSTRACT FROM AUTHOR]

المؤلفون: Chen, Qingyuan^1,2 (AUTHOR) qychen@emails.bjut.edu.cn, Liu, Furong^1,2 (AUTHOR) liufr@bjut.edu.cn, Xu, Guofeng^1,2 (AUTHOR), Yin, Boshuo^1,2 (AUTHOR), Liu, Ming^1,2 (AUTHOR), Xiong, Yifei³ (AUTHOR), Wang, Feiying^1,2 (AUTHOR)

المصدر: Sensors (14248220). Jun2024, Vol. 24 Issue 11, p3676. 10p.

مصطلحات موضوعية: *STRAIN sensors, *STRUCTURAL health monitoring, *DATA conversion, *HUMAN-computer interaction, *SUBSTRATES (Materials science), *OPTICAL sensors

مستخلص: Strain sensors that can rapidly and efficiently detect strain distribution and magnitude are crucial for structural health monitoring and human–computer interactions. However, traditional electrical and optical strain sensors make access to structural health information challenging because data conversion is required, and they have intricate, delicate designs. Drawing inspiration from the moisture-responsive coloration of beetle wing sheaths, we propose using Ecoflex as a flexible substrate. This substrate is coated with a Fabry–Perot (F–P) optical structure, comprising a "reflective layer/stretchable interference cavity/reflective layer", creating a dynamic color-changing visual strain sensor. Upon the application of external stress, the flexible interference chamber of the sensor stretches and contracts, prompting a blue-shift in the structural reflection curve and displaying varying colors that correlate with the applied strain. The innovative flexible sensor can be attached to complex-shaped components, enabling the visual detection of structural integrity. This biomimetic visual strain sensor holds significant promise for real-time structural health monitoring applications. [ABSTRACT FROM AUTHOR]

المؤلفون: de Mooij, Cornelis¹ (AUTHOR) info@cornelisdemooij.com, Martinez, Marcias² (AUTHOR) mmartine@clarkson.edu

المصدر: Sensors (14248220). Jun2024, Vol. 24 Issue 11, p3562. 23p.

مصطلحات موضوعية: *STRAIN sensors, *DISTRIBUTED sensors, *FINITE element method, *DIGITAL image correlation, *BENCHMARK problems (Computer science), *CALIBRATION

مستخلص: Two shape-sensing algorithms, the calibration matrix (CM) method and the inverse Finite Element Method (iFEM), were compared on their ability to accurately reconstruct displacements, strains, and loads and on their computational efficiency. CM reconstructs deformation through a linear combination of known load cases using the sensor data measured for each of these known load cases and the sensor data measured for the actual load case. iFEM reconstructs deformation by minimizing a least-squares error functional based on the difference between the measured and numerical values for displacement and/or strain. In this study, CM is covered in detail to determine the applicability and practicality of the method. The CM results for several benchmark problems from the literature were compared to the iFEM results. In addition, a representative aerospace structure consisting of a twisted and tapered blade with a NACA 6412 cross-sectional profile was evaluated using quadratic hexahedral solid elements with reduced integration. Both methods assumed linear elastic material conditions and used discrete displacement sensors, strain sensors, or a combination of both to reconstruct the full displacement and strain fields. In our study, surface-mounted and distributed sensors throughout the volume of the structure were considered. This comparative study was performed to support the growing demand for load monitoring, specifically for applications where the sensor data is obtained from discrete and irregularly distributed points on the structure. In this study, the CM method was shown to achieve greater accuracy than iFEM. Averaged over all the load cases examined, the CM algorithm achieved average displacement and strain errors of less than 0.01%, whereas the iFEM algorithm had an average displacement error of 21% and an average strain error of 99%. In addition, CM also achieved equal or better computational efficiency than iFEM after initial set-up, with similar first solution times and faster repeat solution times by a factor of approximately 100, for hundreds to thousands of sensors. [ABSTRACT FROM AUTHOR]