Nanostructured materials have attracted considerable interest over the last few decades to enhance sensing capabilities thanks to their unique properties and large surface area. In particular, noble metal nanostructures offer several advantages including high stability, non-toxicity and excellent electrochemical behaviour. However, in recent years the great expansion of point-of-care (POC) and wearable systems and the attempt to perform measurements in tiny spaces have also risen the need of increasing sensors miniaturization. Fast constant potential electrodeposition techniques have been proven to be an efficient way to obtain conformal platinum and gold nanostructured layers on macro-electrodes. However, this technique is not effective on micro-electrodes. In this paper, we investigate an alternative one-step deposition technique of platinum nanoflowers on micro-electrodes by linear sweep voltammetry (LSV). The effective deposition of platinum nanoflowers with similar properties to the ones deposited on macro-electrodes is confirmed by morphological analysis and by the similar roughness factor (~200) and capacitance (~18 $\mathsf{\mu }$ F/mm ${}^2$ ). The electrochemical behaviour of the nanostructured layer is then tested in an solid-contact (SC) $L{i}^{+}$ -selective micro-electrode and compared to the case of macro-electrodes. The sensor offers Nernstian calibration with same response time (~15 s) and a one-order of magnitude smaller limit of detection (LOD) ( $2.6\times {10}^{-6}$ ) with respect to the macro-ion-selective sensors (ISE). Finally, sensor reversibility and stability in both wet and dry conditions is proven.

A time-dependent electrochemical impedance spectroscopy (EIS) model is presented using the finite element method (FEM) to simulate a 2D interdigitated electrode in an aqueous NaCl electrolyte. Developed in COMSOL Multiphysics, the model incorporates ion transport, electric field distribution, Stern layer effects, and electrode sheet resistance, governed by the Poisson and Nernst–Planck equations. This model can predict the transient current response to an applied excitation voltage, which gives information about the dynamics of the electrochemical system. The simulation results are compared with the experimental data, reproducing key features of the measurements. The transient current response indicates the need for multiple excitation cycles to stabilize the impedance measurement. At low frequencies (100 kHz), the voltage drop due to sheet resistance dominates. Moreover, the amplitude of the excitation voltage influences the EIS measurement, higher amplitudes (above 0.1 V) lead to non-linear impedance behavior, particularly at low ion concentrations. Discrepancies at low frequencies suggest that Faradaic processes may need to be incorporated for improved accuracy. Overall, this model provides quantitative insights for optimizing EIS sensor design and highlights critical factors for high-frequency and low-concentration conditions, laying the foundation for future biosensing applications with functionalized electrodes.

This manuscript provides a comprehensive review of the design, implementation, and advancements in integrated circuits (ICs) for electrochemical sensing, with a focus on biomedical and molecular applications. It begins by discussing the fundamental principles of electrochemical sensing and core modalities, including potentiometry, amperometry, impedimetry, and ISFET-based sensing, highlighting their unique requirements and challenges. A detailed analysis of state-of-the-art readout circuit architectures is presented, emphasizing strategies for achieving high dynamic range (DR), low noise, and enhanced stability while minimizing leakage currents. Both resistive and capacitive transimpedance amplifiers (TIAs) and current conveyor (CC)-based circuits are examined, exploring critical trade-offs between speed, power consumption, and noise performance. This review also discusses emerging applications such as DNA sequencing and molecular sensing, covering both ISFET and nanopore-based approaches, to showcase recent advancements in high-throughput, high-speed, and low-power interface circuit designs. By highlighting the challenges of the readout-circuit miniaturization, integration, and scalability, as well as the current limitations in existing approaches, this review provides a comprehensive synthesis of advancements in high-performance electrochemical readout architectures and their potential to address the evolving demands of modern biomedical applications.

Measuring the electrical conductivity (EC) of plant substrates is an effective way to assess their nutrient content. This study aims to compare the performance of EC sensors with varying electrode sizes and spacings when embedded in a plant substrate. The range of electrode sizes and spacings varied from 0.1 mm to 10 mm. The EC electrodes were embedded in a porous plant substrate and subjected to wet–dry cycles. The results showed that the electrodes with larger electrode dimensions and spacing produce valid EC values.