# Paper and Fiber-Based Bio-Diagnostic Platforms: Current Challenges and Future Needs
## 2 Major Challenges and Opportunities
### Other Considerations  
Have the great potential of paper/fiber materials been fully acknowledged by diagnosis manufacturers? Can paper/fiber materials overcome the existing limitations of bio-diagnostic platforms? Would it be possible for an entire bio-analytical assay to be built upon a single type of paper/fiber material? If so, can paper/fiber meet the necessary performance requirements of an efficient bio-analytical platform, such as sensitivity, specificity, cost-effectiveness, and rapid analysis, etc.? To exploit the full potential of paper/fiber materials for bio-analytical applications, these questions need to be addressed. Several other essential points are also worthy of consideration; the following section outlines some of these aspects:  
1. In paper/fiber diagnostic platforms (especially dipsticks), certain segments of the platforms are impregnated with different biomolecular entities, such as antibodies, that specifically bind to the analyte of interest [3]. In this regard, the question might be raised about the yield for such specific binding when dealing with impregnated paper/fiber networks. What is the variation in the uptake or conjugation of the analytes? How consistent is the occurrence of conjugation and the release from conjugation? How fast or slow do these binding and release processes occur? Are these rates reproducible for such assays?
2. Another aspect of paper/fiber platforms that requires attention is the possibility of contamination of the platforms during the fabrication or treatment processes (Table 3). Cross-contamination from the run-over (spillage) between adjacent reagents remains a separate issue [171; 172; 173]. Several efforts have been made to curtail these contamination effects, including the development of hydrophobic barriers designed within the structure of the paper-based devices that partially addresses the spillage of the reagents [171; 172; 173; 174]. However, there is also a risk of toxicity for the biological samples when they are in close contact with the fabrication materials, such as waxes, paraffins, or toxic chemicals used in the techniques for functional modification [3]. How can the risk of contamination be fully eliminated from the fabrication, treatment, and operation procedures of paper-/fiber-based devices? Can the incompatibility of the surfactants with proteins be carefully evaluated?
3. Some of the latest advances in the development of paper-/fiber-based devices offer complex platforms that are hard to be reproduced on an industrial scale. Intricacies can also occur in the protocols, which are then beyond the expertise of the laboratory technicians who perform the tests as their everyday routine (Table 3). Multilayered platforms that are composed of several different segments that need to be carefully assembled prior to test application, layers that are often attached with adhesive components that most likely denature/deactivate analytes when placed in close proximity of the biomolecules, seem less likely to become the next generation of conventional, reproducible, bio-analytical devices used in day-to-day clinical practice. In that perspective, the development of novel platforms with less complexity in fabrication and application should provide a higher probability for prototype development and commercialization.