DESCRIPTION (provided by applicant): Human immunodeficiency virus (HIV) has caused more than 39 million deaths and takes the lives of more than 1.5 million people per year. Antiretroviral therapy (ART) has been highly effective in reducing mortality and expanding access to ART in developing countries has averted more than 5 million HIV-related deaths. The expansion of access to ART has given rise to urgent challenges in early diagnosis, timely ART initiation, and treatment monitoring for timely diagnosis of ART failure in resource-limited settings, where there are limited laboratory infrastructure and trained staff. Regular viral load testing is the most accurate and preferred approach for ART monitoring and is recognized and recommended by the World Health Organization (WHO) guidelines for HIV management in resource-limited settings. In developed countries, nucleic acid-based assays are used for HIV load testing. However, these assays are expensive, laboratory-based, and technically complex, and cannot be easily accessed in resource-limited settings. Thus, to increase access to HIV care with regular ART monitoring in low- and middle-income countries, there is an urgent need for inexpensive, rapid, sensitive, and specific HIV load monitoring tools. In this proposal, building upon our prior expertise, we will use nano- and micro-scale approaches to develop a reliable microchip platform for point-of-care (POC) viral load testing. Our proposed platform technology relies on three engineering and biology related technological advances: (i) on-chip capture of multiple HIV subtypes using anti-gp120/gp41 antibodies with high efficiency and specificity, (ii) sensitive label-free electrical detection of viral lysate using a portable system and (iii) paper- based microfluidics with printed flexible graphene-modified electrodes. Our microchip fabrication is simple, inexpensive, and mass-producible as we print microelectrodes on paper substrates using conductive inks for only a few pennies per chip. Our prior published work has shown the proof-of-concept that multiple HIV subtypes (A, B, C, D, E, G, and panel) can be selectively captured and detected from a fingerprick volume of blood (<100 µL) with clinically relevant virus concentrations for ART monitoring using electrical sensing of viral lysate on-chip. This diagnostic platform technology is broadly applicable to other infectious diseases such as hepatitis, malaria, pox, tuberculosis, and influenza. We have shown the ability of the proposed microchip technology to detect KSHV, EBV, and E. coli in biological samples. The main aim of the proposed study is developing an inexpensive (<$1), disposable, and mass-producible paper-based microfluidic device that is automated to handle whole blood samples (<100 µL) and to rapidly (<30 minutes) detect and count HIV.