Highly Stretchable, Self-Adhesive, Direction-Aware Wireless Hydrogel-MMT Strain Sensors via a Gradient Structure of Intersecting Networks

Hydrogels are considered as an ideal material for bioelectronic devices to fulfill the requirements of various applications. However, integrating self-adhesion properties, high stretchability, good sensing performance, and direction-aware functionality into a single hydrogel strain sensor remains a significant challenge and has been seldom reported. In this study, through the characteristics of montmorillonite (MMT) adsorption, we designed a gradient intersecting strategy based on bifunctional MMT nanoparticles. These nanoparticles act as both cross-linking agents and conductive components to strongly intersect the hydrogel and the conductive networks, preventing them from sliding against each other. Thus, the hydrogel sensor had a wide range of adjustable mechanical properties and good adhesion on various substrates. Moreover, the hydrogel sensor can detect both large- and small-scale human activities and achieves direction awareness. Importantly, the hydrogel sensor can be used to construct a wireless sensor system to monitor human movement in real time. This work provides a strategy for the design of the next-generation flexible strain sensors and a method for the development of multifunctional MMT materials, expanding the application of both MMT materials and hydrogel sensors

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

Coexistence of Antiadhesion Performance, Intrinsic Stretchability, and Transparency

Antiadhesion performance, stretchability, and transparency are highly desirable properties for materials and devices in numerous applications. However, the existing strategies for imparting materials with antiadhesion performance generally induce rigidity and opacity, and principle is yet to be provided for designing materials that combine these important parameters. Here, we show that four factors including a low surface energy, appropriate cross-linking, availability of a homogeneous and amorphous composite, and a smooth material surface can be used to design an intrinsically stretchable and transparent polymer film with antiadhesion performance against various liquids including water, diiodomethane, hexadecane, cooking oil, and pump oil. The film can be obtained via simply molding a waterborne polymer network at ambient temperature. Furthermore, the film can retain its antiadhesion performance and outstanding transparency even when it is subjected to large mechanical deformations reaching up to 1800%, and its maximal fracture strain exceeds 3000%. These design concepts offer a general platform for achieving multiple material functionalities, and may open new avenues for the surface functionalization of stretchable materials and devices

A Surface-Confined Gradient Conductive Network Strategy for Transparent Strain Sensors toward Full-Range Monitoring

The development of transparent and flexible sensors suitable for the full-range monitoring of human activities is highly desirable, yet presents a daunting challenge due to the need for a combination of properties such as high stretchability, high sensitivity, and good linearity. Gradient structures are commonly found in many biological systems and exhibit excellent mechanical properties. Here, we report a novel surface-confined gradient conductive network (SGN) strategy to construct conductive polymer hydrogel-based stain sensors (CHSS). This CHSS showed an ultrahigh stretchability of 4000% strain, transparency above 90% at a wavelength of 600 nm, as well as skin-like Young’s modulus of 40 kPa. Impressively, the sensitivity was improved to 3.0 and outstanding linear sensing performance was achieved simultaneously in the ultrawide range of 0% to 4000% strain with a high R-square value of 0.994. With the help of SGN strategy, this CHSS was able to monitor both large-scale and small-scale human motions and activities. This SGN strategy can open a new avenue for the development of novel flexible strain sensors with excellent mechanical, transparent, and sensing performance for full-range monitoring of human activities

A Surface-Confined Gradient Conductive Network Strategy for Transparent Strain Sensors toward Full-Range Monitoring

The development of transparent and flexible sensors suitable for the full-range monitoring of human activities is highly desirable, yet presents a daunting challenge due to the need for a combination of properties such as high stretchability, high sensitivity, and good linearity. Gradient structures are commonly found in many biological systems and exhibit excellent mechanical properties. Here, we report a novel surface-confined gradient conductive network (SGN) strategy to construct conductive polymer hydrogel-based stain sensors (CHSS). This CHSS showed an ultrahigh stretchability of 4000% strain, transparency above 90% at a wavelength of 600 nm, as well as skin-like Young’s modulus of 40 kPa. Impressively, the sensitivity was improved to 3.0 and outstanding linear sensing performance was achieved simultaneously in the ultrawide range of 0% to 4000% strain with a high R-square value of 0.994. With the help of SGN strategy, this CHSS was able to monitor both large-scale and small-scale human motions and activities. This SGN strategy can open a new avenue for the development of novel flexible strain sensors with excellent mechanical, transparent, and sensing performance for full-range monitoring of human activities