In the context of global population growth expected in the future, enhancing the agri-food yield is crucial. Plant diseases significantly impact crop production and food security. Modern microfluidics offers a compact and convenient approach for detecting these defects. Although this field is still in its infancy and few comprehensive reviews have explored this topic, practical research has great potential. This paper reviews the principles, materials, and applications of microfluidic technology for detecting plant diseases caused by various pathogens. Its performance in realizing the separation, enrichment, and detection of different pathogens is discussed in depth to shed light on its prospects. With its versatile design, microfluidics has been developed for rapid, sensitive, and low-cost monitoring of plant diseases. Incorporating modules for separation, preconcentration, amplification, and detection enables the early detection of trace amounts of pathogens, enhancing crop security. Coupling with imaging systems, smart and digital devices are increasingly being reported as advanced solutions.

Microfluidics, also called lab-on-a-chip, represents an emerging research platform that permits more precise and manipulation of samples at the microscale or even down to the nanoscale (nanofluidic) including picoliter droplets, microparticles, and microbes within miniaturized and highly integrated devices. This groundbreaking technology has made significant strides across multiple disciplines by providing an unprecedented view of physical, chemical, and biological events, fostering a holistic and an in-depth understanding of complex systems. The application of microfluidics to address the challenges in environmental science is likely to contribute to our better understanding, however, it\'s not yet fully developed. To raise researchers\' interest, this discussion first delineates the valuable and underutilized environmental applications of microfluidic technology, ranging from environmental surveillance to acting as microreactors for investigating interfacial dynamic processes, and facilitating high-throughput bioassays. We highlight, with examples, how rationally designed microfluidic devices lead to new insights into the advancement of environmental science and technology. We then critically review the key challenges that hinder the practical adoption of microfluidic technologies. Specifically, we discuss the extent to which microfluidics accurately reflect realistic environmental scenarios, outline the areas to be improved, and propose strategies to overcome bottlenecks that impede the broad application of microfluidics. We also envision new opportunities and future research directions, aiming to provide guidelines for the broader utilization of microfluidics in environmental studies.

Heart failure represents a primary cause of hospitalization and mortality in both developed and developing countries, often necessitating heart transplantation as the only viable recovery path. Despite advances in transplantation medicine, organ rejection remains a significant post-operative challenge, traditionally monitored through invasive endomyocardial biopsies (EMB). This study introduces a rapid prototyping approach to organ rejection monitoring via a sensor-integrated flexible patch, employing electrical impedance spectroscopy (EIS) for the non-invasive, continuous assessment of resistive and capacitive changes indicative of tissue rejection processes. Utilizing titanium-dioxide-coated electrodes for contactless impedance sensing, this method aims to mitigate the limitations associated with EMB, including procedural risks and the psychological burden on patients. The biosensor\'s design features, including electrode passivation and three-dimensional microelectrode protrusions, facilitate effective monitoring of cardiac rejection by aligning with the heart\'s curvature and responding to muscle contractions. Evaluation of sensor performance utilized SPICE simulations, scanning electron microscopy, and cyclic voltammetry, alongside experimental validation using chicken heart tissue to simulate healthy and rejected states. The study highlights the potential of EIS in reducing the need for invasive biopsy procedures and offering a promising avenue for early detection and monitoring of organ rejection, with implications for patient care and healthcare resource utilization.

Legionella pneumophila has been pinpointed by the World Health Organization as the highest health burden of all waterborne pathogens in the European Union and is responsible for many disease outbreaks around the globe. Today, standard analysis methods (based on bacteria culturing onto agar plates) need several days (~12) in specialized analytical laboratories to yield results, not allowing for timely actions to prevent outbreaks. Over the last decades, great efforts have been made to develop more efficient waterborne pathogen diagnostics and faster analysis methods, requiring further advancement of microfluidics and sensors for simple, rapid, accurate, inexpensive, real-time, and on-site methods. Herein, a lab-on-a-chip device integrating sample preparation by accommodating bacteria capture, lysis, and DNA isothermal amplification with fast (less than 3 h) and highly sensitive, colorimetric end-point detection of L. pneumophila in water samples is presented, for use at the point of need. The method is based on the selective capture of viable bacteria on on-chip-immobilized and -lyophilized antibodies, lysis, the loop-mediated amplification (LAMP) of DNA, and end-point detection by a color change, observable by the naked eye and semiquantified by computational image analysis. Competitive advantages are demonstrated, such as low reagent consumption, portability and disposability, color change, storage at RT, and compliance with current legislation.

Following the relaxation of COVID-19 restrictions, other respiratory viruses such as influenza and respiratory syncytial virus (RSV), whose transmission were decreased due to COVID-19 precautions, are rising again. Because of similar clinical features and reported co-infections, multiplex detection of SARS-CoV-2, influenza A/B, and RSV is required to use specific treatments. This study assessed an extraction-free sample preparation (heat treatment at 95°C for 3 minutes) for multiplex detection using rRT-PCR. Despite an observed Ct-delay (∆Ct) averageing 1.26 compared to the standard method, an acceptable total sensitivity of 92 % and a negative predictive value (NPV) of 96 % were obtained. Moreover, Implementation on a microfluidic chip demonstrated efficiency, maintaining an excellent correlation (R2=0.983) with the standard method. Combining this extraction-free procedure with rRT-PCR on a microfluidic chip seems promising, because it simplifies the design and reduces the cost and complexity of the integrated assay for multiplex detection of SARS-CoV-2, influenza A/B, and RSV.

This review reports diverse microfluidic systems utilizing surface-enhanced Raman scattering (SERS) detection for disease diagnosis. Integrating SERS detection technology, providing high-sensitivity detection, and microfluidic technology for manipulating small liquid samples in microdevices has expanded the analytical capabilities previously confined to larger settings. This study explores the principles and uses of various SERS-based microfluidic devices developed over the last two decades. Specifically, we investigate the operational principles of documented SERS-based microfluidic devices, including continuous-flow channels, microarray-embedded microfluidic channels, droplet microfluidic channels, digital droplet channels, and gradient microfluidic channels. We also examine their applications in biomedical diagnostics. In conclusion, we summarize the areas requiring further development to translate these SERS-based microfluidic technologies into practical applications in clinical diagnostics.

Cancer is one of the leading causes of death in the 21st century, with metastasis of cancer attributing to 90% of cancer-related deaths. Therefore, to improve patient outcomes there is a need for better preclinical models to increase the success of translating oncological therapies into the clinic. Current traditional staticin vitromodels lack a perfusable network which is critical to overcome the diffusional mass transfer limit to provide a mechanism for the exchange of essential nutrients and waste removal, and increase their physiological relevance. Furthermore, these models typically lack cellular heterogeneity and key components of the immune system and tumour microenvironment. This review explores rapidly developing strategies utilising perfusable microphysiological systems (MPS) for investigating cancer cell metastasis. In this review we initially outline the mechanisms of cancer metastasis, highlighting key steps and identifying the current gaps in our understanding of the metastatic cascade, exploring MPS focused on investigating the individual steps of the metastatic cascade before detailing the latest MPS which can investigate multiple components of the cascade. This review then focuses on the factors which can affect the performance of an MPS designed for cancer applications with a final discussion summarising the challenges and future directions for the use of MPS for cancer models.

Given the growing importance of lab-on-a-chip in a number of fields, such as medical diagnosis or environmental analysis, the fact that the current fabrication process relies mainly on oil-based polymers raises an ecological concern. As an eco-responsible alternative, we presented, in this article, a manufacturing process for microfluidic devices from chitosan, a bio-sourced, biodegradable, and biocompatible polysaccharide. From chitosan powder, we produced thick and rigid films. To prevent their dissolution and reduce their swelling when in contact with aqueous solutions, we investigated a film neutralization step and characterized the mechanical and physical properties of the resulting films. On these neutralized chitosan films, we compared two micropatterning methods, i.e., hot embossing and mechanical micro-drilling, based on the resolution of microchannels from 100 µm to 1000 µm wide. Then, chitosan films with micro-drilled channels were bonded using a biocompatible dry photoresist on a glass slide or another neutralized chitosan film. Thanks to this protocol, the first functional chitosan microfluidic devices were prepared. While some steps of the fabrication process remain to be improved, these preliminary results pave the way toward a sustainable fabrication of lab-on-a-chip.

Shrink film is a thin sheet of polystyrene plastic that shrinks to 25-40% of its original size when heated. This study investigated the shrinkage factor of the film at different temperatures and baking times to determine the optimal fabrication recipe for shrink film microfluidic device production. Additionally, this study characterized the properties of shrink film, including minimum possible feature size and cross-section geometries, using manual engraving and the CAMEO 4 automated cutting machine. The optimal shrinkage factor ranged from 1.7 to 2.9 at 150 °C and a baking time of 4 min, producing the ideal size for microfluidic device fabrication. The X- and Y-axes shrank ~2.5 times, while Z-axis thickened by a factor of ~5.8 times. This study achieved a minimum feature size of 200 microns, limited by the collapsing of channel sidewalls when shrunk, leading to blockages in the microchannel. These findings demonstrate the feasibility and versatility of using shrink film as a cost-effective and efficient material for the rapid fabrication of microfluidic devices. The potential applications of this material in various fields such as the medical and biomedical industries, bacteria and algae culture and enumeration are noteworthy.

Microfluidics has emerged as a robust technology for diverse applications, ranging from bio-medical diagnostics to chemical analysis. Among the different characterization techniques that can be used to analyze samples at the microfluidic scale, the coupling of photonic detection techniques and on-chip configurations is particularly advantageous due to its non-invasive nature, which permits sensitive, real-time, high throughput, and rapid analyses, taking advantage of the microfluidic special environments and reduced sample volumes. Putting a special emphasis on integrated detection schemes, this review article explores the most relevant advances in the on-chip implementation of UV-vis, near-infrared, terahertz, and X-ray-based techniques for different characterizations, ranging from punctual spectroscopic or scattering-based measurements to different types of mapping/imaging. The principles of the techniques and their interest are discussed through their application to different systems.