Despite substantial progress in the development of wearable and flexible monitoring systems that conform to the epidermis, most designs focus on either physiological signs such as the electrocardiogram (ECG) results, respiration rate, or metabolites, and ignore the dynamic fluctuations of pH and temperature in sweat during on‐body tests. An advanced butterfly‐inspired hybrid epidermal biosensing (bi‐HEB) patch is presented here, which is interfaced with a custom‐developed miniaturized monitoring system. The patch incorporates a novel transducing layer of nanoporous carbon and MXene (NPC@MXene) for sensitive and durable detection of biomarkers in sweat. The bi‐HEB patch is composed of a glucose biosensor accompanied by pH and temperature sensors to precisely quantify glucose as well as two biopotential electrodes, allowing real‐time recording of electrophysiological (EP) signals. The NPC@MXene‐based glucose biosensor demonstrates an excellent sensitivity of 100.85 µAmm−1 cm−2 within physiological levels (0.003−1.5 mm), and variations in pH and temperature during on‐body perspiration monitoring are calibrated by employing a correction approach. In parallel, the EP electrodes exhibit skin‐electrode contact impedance and biopotential signals similar to those of conventional Ag/AgCl electrodes. Finally, the bi‐HEB patch integrated wearable system is used to accurately monitor sweat glucose and ECG of human subjects participating in indoor physical activities.

Perovskite solar cells (PSCs) have captured the attention of the global energy research community in recent years by showing an exponential augmentation in their performance and stability. The supremacy of the light-harvesting efficiency and wider band gap of perovskite sensitizers have led to these devices being compared with the most outstanding rival silicon-based solar cells. Nevertheless, there are some issues such as their poor lifetime stability, considerable J–V hysteresis, and the toxicity of the conventional constituent materials which restrict their prevalence in the marketplace. The poor stability of PSCs with regard to humidity, UV radiation, oxygen and heat especially limits their industrial application. This review focuses on the in-depth studies of different direct and indirect parameters of PSC device instability. The mechanism for device degradation for several parameters and the complementary materials showing promising results are systematically analyzed. The main objective of this work is to review the effectual strategies of enhancing the stability of PSCs. Several important factors such as material engineering, novel device structure design, hole-transporting materials (HTMs), electron-transporting materials (ETMs), electrode materials preparation, and encapsulation methods that need to be taken care of in order to improve the stability of PSCs are discussed extensively. Conclusively, this review discusses some opportunities for the commercialization of PSCs with high efficiency and stability.

No abstract

While state‐of‐the‐art skin‐adhering fibrous electrodes have distinct benefits in personal wearable bioelectronics, considerable challenges persist in the production of fibrous‐based soft conductive biosensing nanomaterials and their integration into efficient multisensing platforms. Here, an electrochemical‐electrophysiological multimodal biosensing patch based on MXene/fluoropolymer nanofiber‐derived hierarchical porous TiO2 nanocatalyst interconnected 3D fibrous carbon nanohybrid electrodes is reported. The nanohybrid electrode is produced via a one‐step laser carbonaceous thermal oxidation, resulting in excellent elctroconductivity (sheet resistance = 15.6 Ω sq−1), rich active edges for effective electron transmission, and abundant support for enzyme immobilization. The features are attributed to three synergistic effects: i) conductivity of the interior, unoxidized MXene layers, ii) quick heterogeneous electron transmission of the exterior TiO2 nanoparticles, and iii) the porous disordered carbon's electron “bridge” effects. Based on the foregoing, the nanohybrid modified biosensing patch integrated into textile is demonstrated to be capable of simultaneously and precisely monitoring sweat glucose with pH adjustment (sensitivity of 77.12 µA mm−1 cm−2 within physiological concentrations of 0.01–2 × 10−3 m) and electrocardiogram signals (signal‐to‐noise ratio = 37.63 dB). This novel approach paves the way for controlled investigations of the nanohybrid, for several functionalization and design options, and for the mass manufacturing capabilities required in real‐world applications.

Breathable Bioelectronics In article number 2107969, Jae Y. Park and co‐workers develop hierarchically interactive carbon nanofibers from β‐phase rich dehydrofluorinated MXene‐poly(1,1‐difluoroethylene) electrospun nanofibers via laser‐induced carbonization. The β‐phase is converted into an sp2‐hybridized graphitic structure by cyclization/cross‐linking decomposition of hydrogen fluoride and transforms into a conjugated carbon structure during carbonization. The approach generates flexible carbon nanofibers with high carbon yield, conductivity, and stability appropriate for engineering skin‐compatible and breathable electrophyological bioelectronics to develop human‐machine interfaces.

Hybrid Epidermal Biosensing System In article number 2208344, Jae Yeong Park and co‐workers reported in‐depth investigations of electrophysiological parameters with precise glucose level determination using a butterfly inspired hybrid epidermal biosensing (bi‐HEB) patch. As a portable smart healthcare monitoring system, the NPC@MXene‐based bi‐HEB patch was successfully paired with a miniaturized printed circuit board to assess glucose and electrocardiogram of individuals during exercise.

Carbon has an extraordinary ability to bind with itself and other elements, resulting in unique structures for a wide range of applications. Recently, intensive research has been focused on the properties of carbon‐based materials (CBMs) and on increasing their performance by doping them with metals and non‐metallic elements. While materials with excellent performance have been experimentally achieved, a fundamental knowledge of the relationship between the electronic, physical, and electrochemical properties and their structural features, particularly the chemistry of carbon‐based materials remains a top challenge. This review begins with the doping chemistries of CBMs, covering the role of electron affinity, orbital chemistry, the chemistry of band gap, conductivity, bonding type, spin redistribution, and conducting relevant comparisons. These will lead to providing an in‐depth understanding of the overall picture in the CBMs doping chemistry particularly as catalysts. The future research prospects and challenges for doped CBMs are highlighted.

Despite extensive advances in wearable monitoring systems, most designs focus on the detection of physical parameters or metabolites and do not consider the integration of microfluidic channels, miniaturization, and multimodality. In this study, a combination of multimodal (biochemical and electrophysiological) biosensing and microfluidic channel-integrated patch-based wireless systems is designed and fabricated using flexible materials for improved wearability, ease of operation, and real-time and continuous monitoring. The reduced graphene oxide-based microfluidic channel-integrated glucose biosensor exhibits a good sensitivity of 19.97 (44.56 without fluidic channels) μA mM–1 cm–2 within physiological levels (10 μM–0.4 mM) with good long-term and bending stability. All the sensors in the patch are initially validated using sauna gown sweat-based on-body and real-time tests with five separate individuals who perspired three times each. Multimodal glucose and electrocardiogram (ECG) sensing, along with their real-time adjustment based on sweat pH and temperature fluctuations, optimize sensing accuracy. Laser-burned hierarchical MXene–polyvinylidene fluoride-based conductive carbon nanofiber-based dry ECG electrodes exhibit low skin contact impedance (40.5 kΩ cm2) and high-quality electrophysiological signals (signal-to-noise ratios = 23.4–32.8 dB). The developed system is utilized to accurately and wirelessly monitor the sweat glucose and ECG of a human subject engaged in physical exercise in real time.