The use of modern instrumentation for biochemical analysis is impractical in limited-resource settings where electrical power and trained operators may not be available and where analytical solutions must be low-cost, portable, and operationally simple. Fundamentally new approaches that are designed specifically to address the challenges of limited-resource settings are needed. Utilizing paper as a substrate to develop biosensors is attractive because the resources required to produce them are minimal and the materials are ubiquitous and inexpensive. This project will create new device designs that can enable paper-based biosensing. Hydrophilic (wettable) channels will be patterned in paper using hydrophobic (non-wettable) barriers in order to control the transport of sample fluids by wicking. In addition to devising a new strategy for bioanalysis in limited-resource settings, the broader impacts of this research program include the creation of educational opportunities for middle school students (hands-on workshops), high school students (device design challenges and summer internships), and science teachers (classroom kit development).
Due to their low cost and ease of use, paper-based microfluidic devices have gained attention as a platform to develop point-of-use bioassays. Independent of the advances in assay development, the paper-based devices themselves, in spite of their vast potential to facilitate bioanalysis, have received surprisingly little attention. This project aims to build an integrated research and education program centered on developing novel paper-based microfluidic devices that can facilitate biosensing based on chemical and biochemical reactions that occur at the interfaces formed between converging liquid fronts. Devices exploiting this approach will facilitate multiplexed biosensing using assay formats that are traditionally considered to be incompatible with flow-based devices (e.g., chemical reactions). The central hypothesis of this research is that the material properties of the paper (e.g., porosity) and the transport of reaction products (e.g., by diffusion) will ultimately control the analytical performance of these paper-based biosensors. By studying these variables systematically, new strategies for low-cost, paper-based biosensing will be developed. Assays at fluidic interfaces will result in the formation of visible colors that will allow users to easily interpret the results of an assay via visual threshold (qualitative), visual comparisons of intensities to read guides (semi-quantitative), or with image analysis (quantitative). This research is significant because the devices derived from this program span a broad range of applications in bioanalysis and will serve as versatile tools for all forms of analytical chemistry. Potential applications include: (i) environmental monitoring of heavy metals, (ii) food security and nutrient density, (iii) detection of nucleic acids and proteins, and (iv) the development of diagnostic assays that are designed specifically for use in limited-resource settings.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
