Tough and stretchable Fe3O4/MoS2/PAni composite hydrogels with conductive and magnetic properties

Liu

ACS Appl. Mater. Interfaces

et al. 2020

140

107

Stimulus-responsive hydrogels, such as conductive hydrogels and thermoresponsive hydrogels, have been explored extensively and are considered promising candidates for smart materials such as wearable devices and artificial muscles. However, most of the existing studies on stimulus-responsive hydrogels have mainly focused on their single stimulus-responsive property and have not explored multistimulus-responsive or multifunction properties. Although some works involved multifunctionality, the prepared hydrogels were incompatible. In this work, a multistimulus-responsive and multifunctional hydrogel system (carboxymethyl cellulose/poly acrylic-acrylamide) with good elasticity, superior flexibility, and stable conductivity was prepared. The prepared hydrogel not only showed excellent human motion detection and physiological signal response but also possessed the ability to respond to environmental temperature changes. By integrating a conductive hydrogel with a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel to form a bilayer hydrogel, the prepared bilayer also functioned as two kinds of actuators owing to the different degrees of swelling and shrinking under different thermal stimuli. Furthermore, the different thermochromic properties of each layer in the bilayer hydrogel endowed the hydrogel with a thermoresponsive “smart” feature, the ability to display and conceal information. Therefore, the prepared hydrogel system has excellent prospects as a smart material in different applications, such as ionic skin, smart info-window, and soft robotics.

Section: Results and Discussionsupporting

confidence: 72%

Multiple-Stimuli-Responsive and Cellulose Conductive Ionic Hydrogel for Smart Wearable Devices and Thermal Actuators

Liu

ACS Appl. Mater. Interfaces

et al. 2020

140

107

“…On the other hand, conductive MoS 2 provides an easy ion-diffusion path at the electrode/electrolyte interface, which contributes to taking advantage of the electrochemical performance of rGO-Fe 3 O 4 to the maximum extent. As a result, the MoS 2 nanosheet generated on the electrode surface possessing a large surface area provides abundant active Faraday redox reaction sites as well as facilitates electron transfer between electrode and electrolyte. − Meanwhile, the presence of MoS 2 effectively stabilizes the electrode/electrolyte interface and reinforces electrical conductivity. , These benefits could help to inhibit material degradation and slow down capacitance deterioration. Therefore, introducing FeMoO 4 can be concluded as an effective way to solve material degradation on rGO-Fe 3 O 4 electrode surface in Na 2 SO 3 environment under the test conditions.…”

Section: Resultsmentioning

confidence: 99%

Fundamental Insight into the Degradation Mechanism of an rGO-Fe₃O₄ Supercapacitor and Improving Its Capacity Behavior via Adding an Electrolyte Additive

Wang

et al. 2021

Energy Fuels

Reduced graphene oxide (rGO)-Fe3O4 nanosized composites containing various concentrations of reduced graphene oxide (rGO) were synthesized by the hydrothermal method. rGO nanosheet provides a solid framework for Fe3O4, improving the overall conductivity as well as reducing agglomeration of Fe3O4 nanoparticles. rGO-Fe3O4 exhibits a specific surface area of 207.2 m3·g–1 with a total pore volume of 0.203 cm3 g–1. Fabricated into electrode, rGO-Fe3O4 demonstrates a specific capacitance of 182.2 F·g–1 at a current density of 1.25 A·g–1 with a retention rate maintaining at 92.4% after 1000 cycles. Material degradation of the electrode inevitably changes the solid electrolyte interface (SEI) and causes capacitance loss during long-cycle tests. In this regard, advanced surface analysis techniques were applied to better understand the degradation mechanism and reveal possible reactions occurring at the electrode interface after various cycling stages. Strategically, iron molybdate (FeMoO4) has been added as an electrolyte additive in the experiment where molybdenum disulfide (MoS2) formed on the electrode surface and remarkably rejuvenated the capacity with maximum values rising to 186.6, 171.8, and 153.4 F·g–1 at the current densities of 1.25, 2.50, and 3.75 A·g–1 respectively. The notable recovery of capacitance achieved by adding FeMoO4 provides a practical method for solving the problem of material degradation and rejuvenating rGO-Fe3O4 electrode performance in the Na2SO3-based electrolyte.

“…Hydrogel‐based immunoassays/immunosensors with immobilized antibodies have been widely used for the detection of human hormones/growth factors to monitor the biological state of human body. [ 114,156,324 ] For example, the human growth hormone (HGH) is a type of peptide that is vital for the normal growth of all our tissues and development of our bodies. Either an excess or deficient level of HGH can lead to various physical and psychological symptoms.…”

Section: Applications Of Composite Hydrogel‐based Biosensorsmentioning

confidence: 99%

Hydrogel‐based composites: Unlimited platforms for biosensors and diagnostics

Wang

Liu

Wang

et al. 2021

VIEW

The need for biosensing systems, which are capable of reliable and accurate detection of physiological signals and disease biomarkers along with biocompatible surface chemistry and textures for device–human interface, has driven the continuous search for advanced sensing materials, sensing strategies, and device structures. Hydrogels are hydrophilic polymers with high water content and thus akin to human tissues. They are not only able to act as polymeric matrices to load functional materials for bio‐signal transducing, but also stimuli‐responsive to cooperate with the filler materials for further enhanced sensing performance. A vast combination of hydrogels and functional fillers such as biomacromolecules, metal nanostructures, carbon nanomaterials, and two‐dimensional materials beyond graphene has been demonstrated over the last decade for fabrication of biosensors for disease diagnosis and health monitoring. This review article aims to provide an overview of the various hydrogel‐based composites, introduce their preparation protocols, and describe the working principles of their corresponding sensors. Recent development of these sensors for potential diagnosis of diseases such as diabetes, cancers, and cardiovascular diseases is then summarized, followed by stating the current challenges and prospects in this field.