Continuous pH monitoring using a sensor for the early detection of anastomotic leaks.

Anastomotic leaks (AL) and staple line leaks are a serious post-operative complication that can develop following bariatric surgery. The delay in the onset of symptoms following a leak usually results in reactive diagnostics and treatment, leading to increased patient morbidity and mortality, and a clinical and economic burden on both the patient and the hospital. Despite support in literature for pH as a biomarker for early detection of AL, the current methods of pH detection require significant clinician involvement and resources. Presented here is a polyaniline (PANI)-based pH sensor that can be connected inline to surgical drains to continuously monitor peritoneal secretion in real time for homeostatic changes in pH. During this study, the baseline peritoneal fluid pH was measured in two pigs using the PANI sensor and verified using a benchtop pH probe. The PANI sensor was then utilized to continuously monitor the changes in the pH of peritoneal effluent, as a gastric leak was simulated. The inline sensors were able to detect the resulting local changes in drainage pH within 10 min of leak induction. The successful implementation of this sensor in clinical practice can both enable high efficiency continuous monitoring of patient status and drastically decrease the time required to detect AL, thus potentially decreasing the clinical and economic burden incurred by gastric leaks.

All-in-One Graphene Based Composite Fiber: Toward Wearable Supercapacitor.

Graphene fibers (GF) have aroused great interest in wearable electronics applications because of their excellent mechanical flexibility and superior electrical conductivity. Herein, an all-in-one graphene and MnO2 composite hybrid supercapacitor fiber device has been developed. The unique coaxial design of this device facilitates large-scale production while avoiding the risk of short circuiting. The core backbone of the device consists of GF that not only provides mechanical stability but also ensures fast electron transfer during charge-discharge. The introduction of a MnO2 (200 nm in length) hierarchical nanostructured film enhanced the pseudocapacitance dramatically compared to the graphene-only device in part because of the abundant number of active sites in contact with the poly(vinyl alcohol) (PVA)/H3PO4 electrolyte. The entire device exhibits outstanding mechanical strength as well as good electrocapacitive performance with a volumetric capacitance of 29.6 F cm-3 at 2 mv s-1. The capacitance of the device did not fade under bending from 0° to 150°, while the capacitance retention of 93% was observed after 1000 cycles. These unique features make this device a promising candidate for applications in wearable fabric supercapacitors.

Advanced Li-Ion Hybrid Supercapacitors Based on 3D Graphene-Foam Composites.

Li-ion hybrid supercapacitors (LIHSs) have recently attracted increasing attention as a new and promising energy storage device. However, it is still a great challenge to construct novel LIHSs with high-performance due to the majority of battery-type anodes retaining the sluggish kinetics of Li-ion storage and most capacitor-type cathodes with low specific capacitance. To solve this problem, 3D graphene-wrapped MoO3 nanobelt foam with the unique porous network structure has been designed and prepared as anode material, which delivers high capacity, improved rate performance, and enhanced cycle stability. First-principles calculation reveals that the combination of graphene dramatically reduces the diffusion energy barrier of Li+ adsorbed on the surface of MoO3 nanobelt, thus improving its electrochemical performance. Furthermore, 3D graphene-wrapped polyaniline nanotube foam derived carbon is employed as a new type of capacitor-type cathode, demonstrating high specific capacitance, good rate performance, and long cycle stability. Benefiting from these two graphene foam-enhanced materials, the constructed LIHSs show a wide operating voltage range (3.8 V), a long stable cycle life (90% capacity retention after 3000 cycles), a high energy density (128.3 Wh·kg-1), and a high power density (13.5 kW·kg-1). These encouraging performances indicate that the obtained LIHSs may have promising prospect as next-generation energy-storage devices.