Flexible strain sensors are a new generation of flexible and stretchable electronic devices that attracted increasing attention due to their practical applications in many fields. However, maintaining a wide detectable strain range while improving the sensitivity of flexible strain sensors remains challenging. In this study, flexible strain sensors with a large working range based on biaxially stretched carbon nanotubes (CNTs)/polyolefin elastomer (POE) nanocomposites were fabricated. Biaxial stretching was demonstrated to enhance the uniform dispersion and orientation of CNTs, thereby improving the performance of sensors. The optimal stretching ratios (SRs) of nanocomposites were investigated and the data revealed an increment in the sensitivity of sensors with SRs, while the working range first increased after biaxial stretching and decreased at higher SRs. Compared to the 9 wt% CNT/POE-1.0 sensor with a gauge factor (GF) value of 2.37 and a detectable range of 0.5%–230%, the CNT/POE-2.0 sensor exhibited an enhanced sensitivity (GF = 3935.12) coupled with a wider detectable range (0.5%–710%) and better stability. Besides, CNT/POE-2.0 sensor also achieved the monitoring of head movements, mouth opening, facial expression, and physiological signals, showing a potential for use in wearable electronic products. 相似文献
Performance of HDPE/MWCNT composite at high strain rate up to 104 s?1 was investigated in a split Hopkinson pressure bar. The results revealed that the incorporation of MWCNTs into HDPE can enhance the impact strength of HDPE. High strain rate impact has a significant influence on morphology, density, crystallinity and melting temperature of the composite. With increase in strain rate, the densities of both HDPE and HDPE/MWCNT composite decreased. The drop of the density of HDPE/MWCNT composite was quicker than that of HDPE density. This could be the reason that much more cracks were formed in the HDPE/MWCNT composite, which could result in high energy dissipation, during SHPB test. The corporation of MWCNTs did lead to the decrease in yield stress.
Wearable flexible electronic strain sensor devices have gained significant attention in recent years due to their potential for detecting human motion in various scenarios. However, the development of strain sensors with high sensitivity across a wide range of strains remains a major challenge. We present herein a novel strain sensor based on a graded structure thermoplastic polyurethane (TPU)/carbon nanotube (CNT) composite yarn with significantly enhanced mechanical performance imparted by the designed structure. The twisted CNTs/TPU spiral yarn demonstrated a fracture elongation of up to 1066% while maintaining charge conductivity under high-strain conditions. Moreover, it exhibited sensitive changes in resistance versus tensile strain, excellent repeatability, and stability. As a strain sensor, it achieved a gauge factor (GF) of 67.2 within a strain range below 50%, reaching 51.7 in a strain range exceeding 150%. With a fast response time of 0.12 s, it enabled accurate identification of movements in different body parts. These findings highlight the broad application potential of the designed spiral yarn strain sensor in areas such as human motion monitoring and human–computer interaction. 相似文献
A new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi‐walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas. 相似文献
Flexible sensors, made of PVDF-HFP reinforced with carbon nanotubes (CNTs), are manufactured by solvent casting. More specifically, the effect of evaporation temperature and sonication time is explored. It is seen that two effects govern the dispersion of CNT: the sedimentation half-time, and the breakage induced by the ultrasonication process. In this regard, it is found that 60°C is an optimum evaporation temperature to reach the highest value of electrical conductivity, since it offers a good balance between these effects, leading to the creation of a more efficient electrical network. This is also confirmed by the AC analysis, where these samples show the highest characteristic frequencies. The electromechanical results show a greater dependency on evaporation temperature for low sonication times, as the breakage induced by an ultrasonic process is not so pronounced and, therefore, the sedimentation effect plays a more dominant role. In addition, cycling tests show robust electromechanical response with cycling, and creep tests prove good electrical response of the sensors, less than 200 ms in some cases. Finally, proof of concept testing of wrist, shoulder, and neck monitoring highlights the potential of the proposed materials for sensing applications. 相似文献
This study investigates the effect of functionalized nanoclay on dielectric properties in the X-band (8.2-12.4 GHz) of synthesized nitrogen-doped carbon nanotube (N-CNT)/nanoclay/polyvinylidene fluoride (PVDF) nanocomposites prepared via melt-mixing. Montmorillonite nanoclay was functionalized by an aminosilane coupling agent, making the nanoclay more compatible with the organic polymer. N-CNT was synthesized employing a chemical vapor deposition technique. Transmission electron microscopy and optical microscopy were used to assess the morphology of nanocomposites. The incorporation of nanoclay improved the dielectric properties, that is, dissipation factor of N-CNT/PVDF nanocomposites. For instance, incorporation of 0.5 wt% nanoclay into N-CNT/PVDF nanocomposite at 1.0 wt% N-CNT loading resulted in 61% reduction in the dissipation factor (from 0.18 ± 0.01 to 0.07 ± 0.01). The percolation threshold increased from 0.3 to 1.0 wt% of N-CNT by incorporation of 0.5 wt% nanoclay, which expanded the percolation region. In addition, incorporation of 0.5 wt% nanoclay reduced agglomeration area ratio of 1.0 wt% N-CNT/PVDF nanocomposite by 57%. Rheological results indicated collapse of N-CNT networks upon addition of nanoclay to the N-CNT/PVDF nanocomposite, which confirmed the dielectric results. Nitrogen heteroatoms (scattering centers) and functionalized nanoclay were responsible for reducing the dissipation factor. 相似文献
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