High-Performance Sensors Based on Chinese Ink and Water-Based Glue for Detection of Strain, Temperature, and Humidity

Abstract

Flexible sensors with high sensitivity and reproducibility have critical applications in various industrial fields. However, current sensors have not yet been able to respond to diverse signal changes in the environment due to their poor stability, weak conductivity, high cost, and time-consuming integration process. Herein, we used dip-coating technology to prepare multifunctional rubber flexible sensors which were based on the Chinese ink carbon nanoparticle (ICN) and waterbased glue. The prepared flexible sensors have the ability to sensitively detect temperature, humidity, and strain signals. The conductive ICN can well adhere on the elastic substrate (natural rubber latex glove), which gives the flexible sensors excellent structural stability even after 500 cycles. The strain response and recovery time of the flexible sensors are 132.8 and 133.8 ms, respectively. The flexible sensors can sensitively detect tiny pressure, human body movements, pronunciation, and human facial expression. Moreover, the prepared high-performance flexible sensors can also be used as temperature and humidity sensors, which displayed a good linear relationship between resistance change and the external signals. This work developed a simple, green, high-efficiency, and low-cost flexible sensors, which shows promising potential in wearable electronic devices for detection of strain, humidity, and temperature.

Recent Studies on the Humidity Sensor: A Mini Review

“…The humidity sensitive material, which serves as the core of the humidity sensor, has a sensitive signal to water molecules, influencing the conductivity. Hydrogen bonds, 14 intramolecular contacts, 15 electrostatic interactions, 16 hydrophilic and hydrophobic interactions, 17 chemical bonding, 18 etc. are some types of these interactions.…”

Recyclable photoluminescent composites via incorporating ZnS‐based phosphors into dynamic crosslinking elastomeric matrixes

“…[27] They pointed out that the degree of recovery of luminous intensity depends on the degree of the elastomer damage, and the degree of recovery of emitting intensity would be weakened when experiencing multiple stretching due to the internal damage of the elastomer. Inspired by the relationship between microstructure and properties, [60][61][62] we envision that the integrity of elastomeric matrixes is relatively essential for the emitting intensity retention, because of effective lighting energy transfer from the surface to the interior of the matrix and from the matrix to the phosphor. Besides, the integrity of the internal structure ensures tight contact between the matrix and phosphor, eliminating the light scattering and dissipation of energy transfer during the process of light excitation and emission, which is conducive to the emitting intensity retention of samples during multiple external stimuli.…”

Hydrophobic Multifunctional Flexible Sensors with a Rapid Humidity Response for Long-Term Respiratory Monitoring

“…8−13 The daily actions of the human body, such as sweating and respiration, lead to changes in the humidity of the surrounding environment. 11,14,15 Wearable devices can be used to obtain physiological and psychological information about the human body in a noninvasive manner by monitoring changes in sweating and breathing in real time. 12,16,17 Moreover, a humidity sensor has noncontact sensing characteristics that make it an important supplement to contact flexible sensors.…”

“…Flexible sensors that can respond to external stimuli such as strain, pressure, and temperature have received widespread attention because of their potential applications in wearable devices, medical monitoring, flexible robots, and smart prostheses. − Humidity, as an important index in the atmosphere, is very important for the industry, agriculture, and the daily life of humans. − The daily actions of the human body, such as sweating and respiration, lead to changes in the humidity of the surrounding environment. ,, Wearable devices can be used to obtain physiological and psychological information about the human body in a noninvasive manner by monitoring changes in sweating and breathing in real time. ,, Moreover, a humidity sensor has noncontact sensing characteristics that make it an important supplement to contact flexible sensors. , Therefore, endowing flexible sensors with humidity detection capabilities has attracted much attention from researchers. Till date, multifunctional flexible sensors with humidity–strain, humidity–temperature, and humidity–pressure detection capabilities have been reported. ,,, …”