Electrical Double Layer at Various Electrode Potentials: A Modification by Vibration

This paper proposes a vibration model of ions as an improvement over the conventional Gouy–Chapman–Stern theory, which is used to model the electrical double layer capacitance and to study the ionic dynamics at electrode/electrolyte interfaces. Although the Gouy–Chapman–Stern model is successful for small applied potentials, it fails to explain the observed behavior at larger potentials, which are becoming increasingly important as materials with high charge injection capacities are developed. A time-dependent study on ionic transport indicates that ions vibrate near the electrode surface in response to the applied electric field. This vibration allows us to correctly predict the experimentally observed decreasing differential capacitance at high electrode potential. This new model elucidates the mechanism behind the ionic dynamics at solid–electrolyte interfaces, providing useful insight that may be applied to many electrochemical systems in energy storage, photoelectrochemical cells, and biosensing

A Novel Optical Assay System for Bilirubin Concentration Measurement in Whole Blood

As a biomarker for liver disease, bilirubin has been utilized in prognostic scoring systems for cirrhosis. While laboratory-based methods are used to determine bilirubin levels in clinical settings, they do not readily lend themselves to applications outside of hospitals. Consequently, bilirubin monitoring for cirrhotic patients is often performed only intermittently; thus, episodes requiring clinical interventions could be missed. This work investigates the feasibility of measuring bilirubin concentration in whole porcine blood samples using dual-wavelength transmission measurement. A compact and low-cost dual-wavelength transmission measurement setup is developed and optimized to measure whole blood bilirubin concentrations. Using small volumes of whole porcine blood (72 µL), we measured the bilirubin concentration within a range corresponding to healthy individuals and cirrhotic patients (1.2-30 mg/dL). We demonstrate that bilirubin levels can be estimated with a positive correlation (R-square > 0.95) and an accuracy of ±1.7 mg/dL, with higher reliability in cirrhotic bilirubin concentrations (> 4 mg/dL) - critical for high-risk patients. The optical and electronic components utilized are economical and can be readily integrated into a miniature, low-cost, and user-friendly system. This could provide a pathway for point-of-care monitoring of blood bilirubin outside of medical facilities (e.g., patient's home)

70 years of bilirubin sensing: towards the point-of-care bilirubin monitoring in cirrhosis and hyperbilirubinemia

Bilirubin is clinically confirmed as a biomarker for liver health and has been utilized to implement the prognostic systems for cirrhosis and hyperbilirubinemia. Optical and chemical methods have been developed and are widely used to determine blood bilirubin levels within clinical settings. However, due to their instrument complexity, high cost, and space requirements, the existing bilirubinometric technologies do not lend themselves to point-of-care (PoC) applications within the community settings or for real-time monitoring. Consequently, bilirubin monitoring can only be monitored intermittently, resulting in missed episodes that may otherwise require clinical interventions. This review paper aims to explore potential strategies for real-world point-of-care applications. Part one discusses the metabolic pathway of bilirubin and the epidemiology of liver cirrhosis and neonatal hyperbilirubinemia. Part two provides a comprehensive review of existing bilirubinometric techniques and highlights the need for point-of-care bilirubin monitoring. Part three develops a theoretical framework for bilirubin spectroscopy. It explores two potential bilirubin measurement approaches: the multiwavelength (based on the distinct optical signatures of bilirubin) and the photodegradation kinetics approach (which relies on bilirubin degradation under blue light irradiation). Part four outlines future recommendations and provides a perspective towards three possible PoC bilirubin measurement devices for real-world applications, including a homecare testing system, a miniature implant and a neonatal wearable patch. These devices provide an opportunity for extending the reach of bilirubin measurement in locations outside hospitals and clinics

Spin–Orbit Interaction in a Two-Dimensional Hole Gas at the Surface of Hydrogenated Diamond

Hydrogenated diamond possesses a unique surface conductivity as a result of transfer doping by surface acceptors. Yet, despite being extensively studied for the past two decades, little is known about the system at low temperature, particularly whether a two-dimensional hole gas forms at the diamond surface. Here we report that (100) diamond, when functionalized with hydrogen, supports a <i>p</i>-type spin-3/2 two-dimensional surface conductivity with a spin–orbit interaction of 9.74 ± 0.1 meV through the observation of weak antilocalization effects in magneto-conductivity measurements at low temperature. Fits to 2D localization theory yield a spin relaxation length of 30 ± 1 nm and a spin-relaxation time of ∼0.67 ± 0.02 ps. The existence of a 2D system with spin orbit coupling at the surface of a wide band gap insulating material has great potential for future applications in ferromagnet–semiconductor and superconductor–semiconductor devices