Paper-based biosensors-from fabrication to applications: a review

Paper is an eco-friendly, flexible, porous, and adaptable substrate that can be used to quickly detect analytes of interest in low-cost devices and biosensors. Paper-based sensors offer inexpensive platforms for pathogen detection, food quality monitoring, environmental and sun exposure monitoring, and fast, easy, and accurate disease detection. While many significant biomarkers, such as proteins, enzymes, nucleic acids, antibodies, hormones, and so on, have already been identified using paper-based instruments, more study is required to increase sensitivity and identify a wider range of biomarkers. The performance of these sensors varies depending on the platform, manufacturing process, and sensing material employed. This review curtails the history of biosensors to their classification and application in various fields. In addition, we present different detection techniques that are employed in paper-based sensors such as colorimetric, electrochemical, and fluorescence detection. The functionality of a paper-based sensor adopting different approaches, particularly electrochemical and optical methods, is discussed. Here, we review the development (from 2010 to post-COVID) of paper-based sensors in the field of the detection and determination of biomolecules. Furthermore, their constraints and opportunities for future developments are also addressed.