Electrochemical sensors are part of a diverse and evolving world of chemical sensors that are impacted by high demand and ongoing technological advancements. Electrochemical sensors offer benefits like cost-efficiency, short response time, ease of use, good limit of detection (LOD) and sensitivity, and ease of miniaturization while providing consistent analytical results. These sensors are employed in various fields-such as healthcare and diagnostics, environmental monitoring, and the food industry-to detect bacteria, viruses, heavy metals, pesticides, and more. In this review, we provide a comprehensive overview of electrochemical sensing techniques, with a focus on enhancing sensor performance through the integration of vibration and hydrodynamic flow in microfluidic systems. We present a structured comparison of these methods, utilizing tables to highlight the approaches most effective for performance enhancement. Additionally, we classify various electrochemical sensing applications, offering insights into the practical utilization of these two techniques for lowering the LOD. Finally, we present a comparative analysis of relevant studies, highlighting how hydrodynamic flow and vibration impact the sensing mechanism. We also explore the potential of these techniques to facilitate the development of automated, high-throughput microfluidic platforms, thereby optimizing their functionality and efficiency.

This paper focuses on theory and computational modelling of lab-on-a-disc devices of relevance for novel applications discovery and optimal designs.

The limit of detection (LOD), speed, and cost of crucial COVID-19 diagnostic tools, including lateral flow assays (LFA), enzyme-linked immunosorbent assays (ELISA), and polymerase chain reactions (PCR), have all improved because of the financial and governmental support for the epidemic. The most notable improvement in overall efficiency among them has been seen with PCR. Its significance for human health increased during the COVID-19 pandemic, when it emerged as the commonly used approach for identifying the virus. However, because of problems with speed, complexity, and expense, PCR deployment in point-of-care settings continues to be difficult. Microfluidic platforms offer a promising solution by enabling the development of smaller, more affordable, and faster PCR systems. In this review, we delve into the engineering challenges associated with the advancement of high-speed microfluidic PCR equipment. We introduce criteria that facilitate the evaluation and comparison of factors such as speed, LOD, cycling efficiency, and multiplexing capacity, considering sample volume, fluidics, PCR reactor geometry and materials, as well as heating/cooling methods. We also provide a comprehensive list of commercially available PCR devices and conclude with projections and a discussion regarding the current obstacles that need to be addressed in order to progress further in this field.

Many advanced microfluidic Lab-on-disc (LOD) devices require an on-board power supply for powering active components. LODs with an on-board electrical power supply are called electrified-LODs (eLODs) and are the subject of the present review. This survey comprises two main parts. First, we discuss the different means of delivering electrical energy to a spinning disc including slip-ring, wireless power transmission, and on-board power supply. In the second part, we focus on utilizing electrical power on eLODs for three electrokinetic microfluidic processes: electrophoresis, electroosmotic flow, and dielectrophoresis. Electrokinetic phenomena enable propulsion, separation, and manipulation of different fluids and various types of microparticles/cells. We summarize the theoretical and experimental results for all three electrokinetic phenomena enacted on centrifugal platforms. While extensive numerical modeling and experimental research are available for electrokinetics on stationary platforms, there is a noticeable lack of development in this area when executed on rotating platforms. The review concludes by comparing the strengths and weaknesses of different electrokinetic techniques implemented on centrifugal platforms, and additionally, the most promising applications of electrokinetic-assisted eLOD devices are singled out.

The use of multiphase flows in microfluidics to carry dispersed phase material (droplets, particles, bubbles, or fibers) has many applications. In this review paper, we focus on such flows on centrifugal microfluidic platforms and present different methods of dispersed phase material generation. These methods are classified into three specific categories, i.e., step emulsification, crossflow, and dispenser nozzle. Previous works on these topics are discussed and related parameters and specifications, including the size, material, production rate, and rotational speed are explicitly mentioned. In addition, the associated theories and important dimensionless numbers are presented. Finally, we discuss the commercialization of these devices and show a comparison to unveil the pros and cons of the different methods so that researchers can select the centrifugal droplet/particle generation method which better suits their needs.

Detection and monitoring of lactate and glucose levels in biological fluids and cell cultures are essential for understanding metabolic disorders. While electrochemical biosensors are commonly used, traditional enzymatic sensors face challenges related to stability, reproducibility, and cost. To address these limitations, we developed non-enzymatic sensors for lactate and glucose detection using nanostructured nickel oxide (NiO)-modified screen-printed carbon electrodes. The sensors were fabricated by drop-casting a NiO/Nafion/ethanol dispersion onto the working electrode, and their performance was evaluated using cyclic voltammetry and amperometry. Optimal sensitivity and linearity were achieved at a working potential of ∼0.5 V. The sensors exhibited linear responses for both lactate and glucose in the 0.1-5 mM range, with detection limits of 0.03 mM (lactate) and 0.025 mM (glucose), and sensitivities of 1.564 μA/mM (lactate) and 1.842 μA/mM (glucose) in 0.1 M NaOH-KCl electrolyte. To address glucose interference in lactate sensing, dual-sensing strategies were employed by varying Nafion concentration, applying differential potentials, or modifying the sensors with Prussian Blue to achieve selective detection. Validation against commercial lactate and glucose assay kits in cell culture medium showed good agreement, confirming the sensors' accuracy. Finally, the sensor was integrated with a microfluidic chip, demonstrating its potential as a flow-through, enzyme-free metabolic sensor for future organ-on-a-chip applications.