Carbon-based electrodes and sensors for miniaturized blood gas analyzers

Blood gas analyzers are essential tools for assessing respiratory and metabolic function, especially in patients with respiratory conditions such as COVID-19. The pandemic has underscored the need for affordable, compact, and user-friendly point-of-care testing (POCT) devices for decentralized and home care. These analyzers provide real-time information on oxygenation (pO2), ventilation (pCO2), and acid-base balance (pH, pCO2, and HCO3−) by arterial blood analysis. Modern systems also measure electrolytes (e.g., Na+, K+, Ca2+, and Cl−), glucose, and lactate. While widely used in emergency laboratories, ICUs, and operating rooms, their size and complexity hinder their use in ambulances and bedside settings. Overcoming this issue requires the continued development of miniaturized blood gas analyzers compatible with POCT. Carbon-based electrodes have emerged as essential because of their excellent electrical conductivity, chemical stability, biocompatibility, and compatibility with cost-effective production. These properties facilitate the development of compact and environmentally sustainable sensors. In addition, their robustness allows their repeated use, making them highly suitable for both disposable and reusable POCT devices. This review provides an overview of the electrode materials, electrode designs, and sensor technologies used in blood gas analyzers, with a particular focus on miniaturization for POCT applications.