Equipment-Free Quantitative Readout in Paper-Based Point-of-Care Testing

Equipment-free paper-based devices with quantitative readout have gained considerable interests in recent years, due to the features of remarkable cheapness, prominent portability, and excellent user friendliness. These equipment-free strategies have been demonstrated to be able to detect a variety of analytes with good performance, such as metal ions, nucleic acids, and cells, thus showing great potential for point-of-care testing in resource-limited settings. In this review, the latest advances of equipment-free quantitative readout strategies in paper-based point-of-care testing are summarized, including distance-based strategy, counting-based strategy, time-based strategy, and text-based strategy. Each type of equipment-free strategy is sequentially introduced and discussed. Finally, conclusions and perspectives are discussed.