Fabrication of flexible temperature sensors to explore indeterministic data analysis for robots as an application of Internet of Things

Recent Advances in Flexible Temperature Sensors: Materials, Mechanism, Fabrication, and Applications

Flexible electronics is an emerging and cutting-edge technology which is considered as the building blocks of the next generation micro-nano electronics. Flexible electronics integrate both active and passive functions in devices, driving rapid developments in healthcare, the Internet of Things (IoT), and industrial fields. Among them, flexible temperature sensors, which can be directly attached to human skin or curved surfaces of objects for continuous and stable temperature measurement, have attracted much attention for applications in disease prediction, health monitoring, robotic signal sensing, and curved surface temperature measurement. Preparing flexible temperature sensors with high sensitivity, fast response, wide temperature measurement interval, high flexibility, stretchability, low cost, high reliability, and stability has become a research target. This article reviewed the latest development of flexible temperature sensors and mainly discusses the sensitive materials, working mechanism, preparation process, and the applications of flexible temperature sensors. Finally, conclusions based on the latest developments, and the challenges and prospects for research in this field are presented.

A complex wireless sensors model (CWSM) for real time monitoring of dam temperature

The following work is based on real-time temperature monitoring during the construction and during the operation of a dam. For this purpose, we have proposed a sensing model named: the "complex wireless sensors model (CWSM)" for measuring the value of different factors like temperature, humidity and pressure on the dam. The installation of the proposed model has been discussed with its wireless networking. The model contains five types of sensors i.e. humidity, temperature, pressure, sun and irradiance sensors for measuring the variation of different factors. The computation modeling of CWSM has been discussed in the paper. 3-D Finite Element method is used for thermal analysis. As the result, it is concluded that the wireless network will be more suitable for measuring and analyzing the effects of temperature, humidity, water pressure and solar radiation on the dam.

Fabrication of graphene-based sensor for exposure to different chemicals

Opto-chemical sensors are the most significant type of sensors that are widely used to detect a variety of volatile organic compounds and chemicals. This research work demonstrates the fabrication and characterization of an opto-chemical sensor based on a graphene thin film. A 300 nm graphene thin film was deposited on clean glass with the help of RF magnetron sputtering. The structure, surface and quality of the graphene thin film were characterized using XRD, SEM and Raman spectroscopy. For optical characterization, the thin film was exposed to IPA, acetone and toluene (separately) for five, ten and fifteen minutes. The optical transmission was then observed via UV-NIR spectroscopy in the near-infrared range (900 to 1450 nm). The thin film of graphene has expressed a sharp response time and recovery time with high sensitivity for each chemical. However, by comparing the output of the graphene thin film in response to each chemical, it was observed that graphene thin film has a better transmission and sensing rate for exposure to toluene.

Effect of surfactant concentration on the evaporation-driven deposition of carbon nanotubes: from coffee-ring effect to strain sensing

Carbon nanotubes (CNTs) as electrically conductive materials are of great importance in the fabrication of flexible electronic devices and wearable sensors. In this regard, the evaporation-driven self-assembly of CNTs has attracted increasing attention. CNT-based applications are mostly concerned with the alignment of CNTs and the density of CNT films. In the present work, we focus on the latter by trying to achieve an optimal evaporation-driven deposition with the densest CNT ring. Although surfactants are used for effective dispersion and colloidal stabilization of CNTs in the aqueous phase, their excessive usage induces Marangoni eddies in the evaporating sessile droplets, leading to poor ring depositions. Thus, there is an optimum surfactant concentration that contributes to CNTs deagglomeration and results in the densest ring-like deposition with relatively high thickness. We report that this optimum concentration for sodium dodecyl sulfate (SDS) as a surfactant can be approximately considered as much as the concentration of multi-walled carbon nanotubes (MWCNTs) as the colloidal nanoparticles. Optimal depositions show the lowest electrical resistances for each CNT concentration, making them suitable for electronic applications. We also propose the multiple depositions method in which a new droplet is printed after the complete evaporation of the previous droplet. This method can lead to denser rings with a higher conductivity using lower concentrations of CNTs. Lastly, we fabricate strain sensors based on the optimal evaporation-driven deposition of CNTs which show higher gauge factors than the commercial strain gauges, corroborating the applicability of our method.

Fabrication and Characterization of a Highly Sensitive and Flexible Tactile Sensor Based on Indium Zinc Oxide (IZO) with Imprecise Data Analysis

Tactile sensors are widely used in the electronic industry. In the following research work, we proposed a tactile sensor based on indium zinc oxide (IZO) electrodes and used neutrosophic statistics to analyze the capacitance and resistance of the tactile sensor. The tactile sensor was fabricated by depositing the IZO electrodes on a polycarbonate substrate (a thin layer). The IZO was characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible (UV-vis) spectroscopy techniques. The sensor's electrical properties were characterized using an LCR meter, i.e., capacitance and resistance were measured in intervals with respect to changes in the applied force on the sensor at 1 kHz operational frequency. The sensor expressed high sensitivity with quick response and recovery times. The sensor also expressed long-term stability. For the analysis of capacitance and resistance, two statistical approaches, i.e., classical and neutrosophic approaches, were applied, and the better analysis approach for the sensor was found.

Fabrication of a graphene-based sensor to detect the humidity and the temperature of a metal body with imprecise data analysis

Graphene is a 2D material with remarkable properties. The present study demonstrates the fabrication of a graphene-based sensor for measuring the temperature and humidity of a metal body. The graphene sensor was fabricated by depositing a thin film of graphene nanoparticles between silver electrodes (separated by ∼50 μm) on a glass substrate. The graphene thin film was characterized by XRD, Raman spectroscopy and UV-vis techniques. The capacitance and resistance for both the relative humidity (in the range of 0-100% RH) and temperature (in the range of 230-310 K) were measured using an LCR meter at 1 kHz in a controlled chamber. The graphene-based sensor expressed high sensitivity with fast response and recovery times for both humidity and temperature with long stability and low hysteresis curves. The sensor was also tested on a metal body, which expressed a good response time. Moreover, the measured data of capacitance and resistance was analyzed with classical and neutrosophic analysis as an application of modern material statistics. It was observed that neutrosophic analysis is more flexible for analyzing the capacitance and resistance of the fabricated sensor.