Microfluidic paper–based analytical extraction devices (µPAEDs): a cost-effective and portable solution for biomarkers, contaminants and VOC detection

The human body relies on various biological and environmental cues, and regulatory processes for basic functioning and maintenance of health. Thus, by monitoring these cues, which include biomarkers and chemical contaminants, scientists and health professionals can prioritize the health, well-being, and longevity of the general population. These analytes are found in biological and other fluids and are usually extracted using conventional extraction methods like liquid–liquid or solid-phase extraction. Until recently, these methods were used in tandem with conventional detection techniques like LC–MS/MS and GC–MS/MS. However, this inept combination proves to be disadvantageous for the general population due to its higher costs, requirement of specialized equipment and experienced personnel, usage of several organic and environmentally harmful reagents, and a centralized approach. Thus, recently there has been a rise in the usage of microfluidics, particularly µPADs and conventional extraction techniques. By capitalizing on the multifarious advantages of µPADs, including affordability, miniaturization, and dispensable equipment, researchers have developed all-in-one microfluidic paper–based analytical extraction devices (µPAEDs). This approach mitigates the risks associated with the former and improves costs, transportability, and accessibility. Additionally, this novel approach has also been applied to non-invasive detection of volatile organic compounds (VOCs). In this review, we highlight the advancements of µPAEDs to detect myriads of biomarkers and chemical contaminants in samples like blood, breath, and water.