Distance-based microfluidic assays for instrument-free visual point-of-care testing

The increasing numbers of diseases due to food toxins, environmental changes and industrial outputs necessitate the development of a simple, fast, and low-cost technology for monitoring biofluids and environmental samples. The distance-based microfluidic analytical sensors (d-μAS), which rely on distance as a readout signal, offer the advantages of simplicity, being portable, eco-friendly, instrument-free, low-cost, and rapid detection time. Also, it is significant in a setup with limited resources and a lack of skilled personnel. The present review focuses on the progress in substrate preparation, application, advantages, challenges, and future directions of d-μAS. This review will interest the researchers and explore methods for developing high-quality biosensors and their applications in advanced engineering processes.