Electrochemical (bio)sensors are considered clean and powerful analytical tools capable of converting an electrochemical reaction between analytes and electrodes into a quantitative signal.

This work investigates the impact of carbon black (CB) as a porogenic agent and conductive additive in the preparation of electrically conductive nanoporous carbon gels. For this, a series of materials were prepared by the polycondensation of resorcinol/formaldehyde mixtures in the presence of increasing amounts of carbon black. The conductivity of the carbon gel/CB composites increased considerably with the amount of CB, indicating a good dispersion of the additive within the carbon matrix. A percolation threshold of ca. 8 wt.% of conductive additive was found to achieve an adequate “point to point” conductive network. This value is higher than that reported for other additives, owing to the synthetic route chosen, as the additive was incorporated in the reactant’s mixture (pre-synthesis) rather than in the formulation of the electrodes ink (post-synthesis). The CB strongly influenced the development of the porous architecture of the gels that exhibited a multimodal mesopore structure comprised of two distinct pore networks. The microporosity and the primary mesopore structure remained rather unchanged. On the contrary, a secondary network of mesopores was formed in the presence of the additive. Furthermore, the average mesopore size and the volume of the secondary network increased with the amount of CB.

A sustainable catechol biosensor for the analysis of beverages and cosmetics.

Electrochemical sensors integrated into organ-on-a-chip (OoC) - single-organ systems and more complex multi-organ (body-on-a-chip) - microfluidic platforms constitute a rapidly advancing interface between biosensing, microfluidics, and microphysiological systems (MPS), with major implications for biomedical research, drug discovery, toxicology, and personalized medicine. By transducing biochemical and biophysical events at the tissue-device interface into quantifiable electrical signals, these sensors enable real-time, label-free, and highly sensitive monitoring of metabolites, ions, barrier integrity, and cellular activity under physiologically relevant conditions. Within OoC and MPS platforms, electrochemical sensing can be implemented through different integration strategies, including on-chip configurations such as in-line and on-line sensing directly embedded within microfluidic channels, as well as off-chip approaches. The integration of miniaturized and multiplexed electrochemical sensors into MPS enables continuous and high-throughput functional monitoring of key physiological parameters, including metabolic activity variation, biomolecules gradients, barrier function, and responses to drugs and toxic compounds. Multi-OoC configurations benefit from electrochemical readouts to interrogate dynamic inter-organ communication and systemic responses, supporting more predictive human-relevant models. This is mostly relevant for new approach methodologies (NAMs), which aim to reduce animal experimentation while improving human relevance and predictive accuracy. Overall, electrochemical sensor-integrated OoC/MPS platforms represent powerful NAMs aligned with 3Rs (replacement, reduction, and refinement) principles, enabling high-throughput screening, improved physiological relevance, and enhanced predictive modeling for drug development and regulatory applications. In this review, we address recent advances in electrochemical sensor integration within OoC and MPS platforms, discussing fabrication strategies, sensing modalities, and system-level architectures, as well as current challenges and future perspectives.