Recent Progress in Manufacturing Techniques of Printed and Flexible Sensors: A Review.

Boosting electrical and piezoresistive properties of polymer nanocomposites via hybrid carbon fillers: A review

Biochar as an alternative sustainable platform for sensing applications: A review

Fabricating high response humidity sensors can create new-fashioned applications and avenues for stakeholder interaction. Thus, this paper addresses an efficient fabrication route based on consolidated graphene oxide (GO) nanoplatelets inside the polyvinyl chloride (PVC) in presence tricresyl phosphate (TCP) plasticizer by In-situ method. The structure of synthesized GO was verified by X-ray diffraction (XRD) and Fourier transform infrared imaging microscopic analysis (FT-IR-IM). Three different proportions of GO (i.e., 1, 3 and 6 wt.%) were used to fabricate plasticized PVC sensors. The morphology of sensors was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM) techniques. The AFM & TEM images showed that better dispersion of GO nanoplatelets in the PPVC matrix occurred at 1 and 3 wt.%. Furthermore, other measurements such as Raman spectroscopy, mechanical properties and thermogravimetric analysis (TGA) were conducted on the fabricated PVC sensors. Also, the humidity sensing properties were tested in a wide range of relative humidity (11–85 % RH) and frequency (100 Hz–100 kHz). The data manifested that the optimum measuring frequency was 1 kHz. Moreover, the obtained results from humidity sensing at 1 kHz exhibited that sensor 3 (PPVC/GO-3%) possessed higher sensitivity, lower hysteresis with ultrafast response speed (∼ 4 s) and recovery time (∼ 6 s) compared to other sensors. This result reveals excellent possibility of using sensor 3 as humidity sensing for intelligent food packaging and other practical applications.

Ultrafast response humidity sensors based on polyvinyl chloride/graphene oxide nanocomposites for intelligent food packaging

Potential Role of Kesterites in Development of Earth-Abundant Elements-Based Next Generation Technology

Humidity sensors are widespread in many industrial applications, ranging from environmental and meteorological monitoring, soil water content determination in agriculture, air conditioning systems, food quality monitoring, and medical equipment to many other fields. Thus, an accurate and reliable measurement of water content in different environments and materials is of paramount importance. Due to their rich surface chemistry and structure designability, carbon materials have become interesting in humidity sensing. In addition, they can be easily miniaturized and applied in flexible electronics. Therefore, this short review aims at providing a survey of recent research dealing with carbonaceous materials used as capacitive and resistive humidity sensors. This work collects some successful examples of devices based on carbon nanotubes, graphene, carbon black, carbon fibers, carbon soot, and more recently, biochar produced from agricultural wastes. The pros and cons of the different sensors are also discussed in the present review.

Carbon-Based Materials for Humidity Sensing: A Short Review.

Sensors for pH evaluation of concrete were made by a sol–gel process with alizarin yellow as pH indicator. The optical absorbance was measured with a visible spectrophotometer coupled with optical ...

https://journals.sagepub.com/doi/pdf/10.1177/2280800020936540

Sol–gel-entrapped pH indicator for monitoring pH variations in cementitious materials:

This work investigates the printability of Ce-ZrO2/Al2O3 composites through a Digital Light Processing (DLP) technology. Commercially available 10 mol% CeO2 and 12 mol% CeO2-stabilized zirconia were mixed with alumina powders, to provide 11 mol% CeO2-stabilized ZrO2/16 vol% Al2O3 (Ce-ZA16) composite materials. The powders were dispersed under wet conditions, and the homogeneous nanometric dispersion was maintained once added into the liquid monomer. Slurries at several solid loadings were explored, with and without dispersant addition. First, the key role of the dispersant to significantly enhance the solid loading and thus the sintered density was demonstrated. Second, among different dispersant-added slurries at various solid loadings, ranging from 65 to 80 wt%, the best compromise between rheological behavior and curing depth was established. The best formulations, comprised between 70 and 80 wt%, successfully provided fully dense and completely homogeneous composites. 

Barbara Inserra

Papers

Carbon-Based Materials for Humidity Sensing: A Short Review.

Sol–gel-entrapped pH indicator for monitoring pH variations in cementitious materials:

Preparation and characterization of Ce-ZrO2/Al2O3 composites by DLP-based stereolithography