Given the rise in the popularity of wearable electronics that are able to deform into desirable configurations while maintaining electrochemical functionality, stretchable and flexible (hybrid) supercapacitors (SCs) have become increasingly of interest as innovative energy storage devices. Their outstanding power density, long lifetime with low capacitance loss, and appropriate energy density, in particular in hybrid cases make them ideal candidates for flexible electronics. The aim of this review paper is to provide an in-depth discussion of these stretchable and flexible SCs ranging from fabrication to electro-mechanical properties. This review paper begins with a short overview of the fundamentals of charge storage mechanisms and different types of multivalent metal-ion hybrid SCs. The research methods leading up to the current state of these stretchable and flexible SCs are then presented. This is followed by an in-depth presentation of the challenges associated with the fabrication methods for different configurations.Proposed novel strategies to maximize the elastic and electrochemical properties of stretchable/flexible or quasi-solid-state SCs are classified and the pros and cons associated with each are shown. The advances in mechanical properties and the expected advancements for the future of these SCs are discussed in the last section.

Front cover image: Given a rise in the popularity of wearable electronics that are able to deform into desirable configurations while preserving electrochemical functionality, stretchable and flexible supercapacitors (SCs) have become increasingly of interest as innovative energy storage devices. In article number: https://doi.org/10.1002/cey2.320, Amiri et al. investigated various advancements and upcoming prospects of flexible and stretchable SCs including 1D fiber‐like SCs, 2D planar SCs, and 3D SCs. The fundamentals of stretchable SCs such as mechanisms, layouts, materials, and configuration designs associated with each configuration and their effects on mechanical and electrochemical properties are studied in details.

BackgroundThere are a lack of biomarkers which can be used to predict clinical outcomes for multiple sclerosis (MS) patients receiving interferon beta (IFN-β). Thus the objective of this study was to characterize changes in CD4+ T-lymphocyte expression in an unbiased manner following initiation of intramuscular (IM) IFN-β-1a treatment, and then to verify those findings using marker-specific assays.MethodsPeripheral blood specimens were collected from twenty MS patients before and after treatment with intramuscular (IM) IFN-β-1a and were used for isolation of mononuclear cells (PBMCs). mRNA expression patterns of negatively-selected CD4+ T-cells from the PBMCs were analyzed using microarray gene expression technology. IL-12 and IL-23 receptor levels on PBMC-derived CD4+ T-cells were analyzed by flow cytometry. The phosphorylation status of Stat4 was measured by performing densitometry on western blots.ResultsMicroarray analyses demonstrated that mRNA expression of the IL-12Rβ2 gene was uniformly up-regulated in response to IFN-β-1a treatment and was associated with an increased number of IL-12Rβ2+ CD4+ T-cells by flow cytometry in 4 of 6 patients. This finding was substantiated by demonstrating that Stat4 phosphorylation, a transcription factor for IL-12, was increased after treatment. Conversely, the number of IL-23R+ CD4+ T-cells was decreased following treatment.ConclusionsThe IL-12 receptor shares a common subunit, the IL-12Rβ2, with the IL-23 receptor. Both of these receptors have a probable role in regulating IL-17 and TH-17 cells, important mediators of inflammation in multiple sclerosis (MS). Thus, the changes in the numbers of CD4+ T-cells expressing these receptors in response to IFN-β-1a treatment may point to an important mechanism of action for this drug, but further large scale studies are needed to confirm these preliminary observations.