Conductive and self-healing hydrogel for flexible electrochemiluminescence sensor

A temperature and pressure dual-responsive, stretchable, healable, adhesive, and biocompatible carboxymethyl cellulose-based conductive hydrogels for flexible wearable strain sensor

The study aimed to develop a novel temperature and pressure dual-responsive conductive hydrogel with self-healing, self-adhesive, biocompatible, and stretchable properties, for the development of multifunctional anti-counterfeiting and wearable flexible electronic materials. A conductive hydrogel based on carboxymethyl cellulose (CMC) was synthesized by simple "one pot" free radical polymerization of CMC, acrylamide (AAm) and acrylic acid (AAc). The hydrogel displayed temperature responsiveness and possessed an upper critical solution temperature (UCST) value. In addition, hydrogels also had surprising pressure responsiveness. The synthesized hydrogels were characterized by FTIR, TGA, DSC, and XRD analysis. Importantly, the obtained hydrogels exhibited exceptional mechanical properties (stress: 730 kPa, strain: 880%), fatigue resistance, stretchability, self-healing capability, self-adhesive properties, and conductivity. In addition, valuable insights were obtained into the synthesis and application of flexible anti-counterfeiting and camouflage materials by the temperature and pressure dual-responsive hydrogels. Moreover, the prepared hydrogel, with an electrically sensitive perception of external strain (GF = 2.61, response time: 80 ms), can be utilized for monitoring human movement, emotional changes, physiological signals, language, and more, rendering it suitable for novel flexible anti-counterfeiting materials and versatile wearable iontronics. Overall, this study provided novel insights into the simple and efficient synthesis and sustainable manufacturing of environmentally friendly multifunctional anti-counterfeiting materials and flexible electronic skin sensors.

Hydrogels for Chemical Sensing and Biosensing

The development and synthesis of hydrogels for chemical and biosensing are of great value. Hydrogels can be tailored to its own physical structure, chemical properties, biocompatibility, and sensitivity to external stimuli when being used in a specific environment. Herein, hydrogels and their applications in chemical and biosensing are mainly covered. In particular, it is focused on the manner in which hydrogels serve as sensing materials to a specific analyte. Different types of responsive hydrogels are hence introduced and summarized. Researchers can modify different chemical groups on the skeleton of the hydrogels, which make them as good chemical and biosensing materials. Hydrogels have great application potential for chemical and biosensing in the biomedical field and some emerging fields, such as wearable devices.

Superhydrophobic Flexible Strain Sensors Constructed Using Nanomaterials: Their Fabrications and Sustainable Applications

Superhydrophobic flexible strain sensors, which combine superhydrophobic coatings with highly sensitive flexible sensors, significantly enhance sensor performance and expand applications in human motion monitoring. Superhydrophobic coatings provide water repellency, surface self-cleaning, anti-corrosion, and anti-fouling properties for the sensors. Additionally, they enhance equipment durability. At present, many studies on superhydrophobic flexible sensors are still in the early research stage; the wear resistance and stability of sensors are far from reaching the level of industrial application. This paper discusses fundamental theories such as the wetting mechanism, tunneling effect, and percolation theory of superhydrophobic flexible sensors. Additionally, it reviews commonly used construction materials and principles of these sensors. This paper discusses the common preparation methods for superhydrophobic flexible sensors and summarizes the advantages and disadvantages of each method to identify the most suitable approach. Additionally, this paper summarizes the wide-ranging applications of the superhydrophobic flexible sensor in medical health, human motion monitoring, anti-electromagnetic interference, and de-icing/anti-icing, offering insights into these fields.