On Paper Diagnostics: A Brief History and Future Perspectives.

For centuries, diagnostic technologies have played a key role in medicine. Effective diagnostics can help clinicians identify the presence and extent of disease in their patients, as well as their general health. Precipitated by advances in biochemistry, chemistry, and engineering, the 20th and 21st centuries have witnessed rapid advancement in diagnostic technologies. However, these improvements have brought increased complexity and a corresponding move towards more centralized and specialized laboratories. This has led to significant healthcare disparities between high- and low/middle-income regions. However, with the introduction of paper-based diagnostics this paradigm has begun to shift, with new assay formats designed for point-of-care (PoC) or at-home use. By leveraging innovations from multiple fields, these paper-based tests can translate complex assay procedures into easy-to-use, single-step tests for the end user. In this review, we summarize the interdisciplinary beginnings of paper-based diagnostics, detailing their development through market introduction and commercial successes, and discuss the current state-of-the-art. Finally, we highlight areas for improvement and propose pathways that could enable increasingly complex chemistries to be performed on simple paper-based devices.