In the ongoing battle against HIV, early diagnosis is a powerful tool for detecting the virus before it has the chance to cause extensive damage to patients and more importantly before it spreads further. Yet, the current landscape of HIV testing is a patchwork of limitations. Accessible tests lack sufficient sensitivity for early infection whereas those sensitive tests are often costly and far from the reach of the communities that need them most.

This is the challenge that inspired our recent research, through which we have developed a portable device for sensitive HIV detection designed to bypass these long-standing barriers.

Problems with Conventional Tests

Antibody-based HIV tests are quick and affordable for initial screenings. However, these tests fall short during the critical early phase, or “acute stage” of HIV infection when people are most infectious. Since antibodies aren’t yet present during the acute phase, antibody-based tests return a false negative. On the flip side, nucleic acid tests (NAT) can pick up on the virus’s genetic material right away but they are locked away in advanced labs due to their need for expensive equipment and technical expertise. In low-resource settings, where HIV strikes hardest, people face an impossible choice: 1) a convenient test that might miss the infection, or 2) a definitive test that’s out of reach.

This is the gap we set out to fill. Imagine a test with the accuracy of nucleic acid-based methods and with the simplicity and affordability of antibody tests, available right where it’s needed most.

Reinventing Testing with the Power of Engineering

Paper, as it turns out, is an extraordinary ally in diagnostics. By pairing cellulose paper with 3D printing technology, we’ve developed a portable device that uses paper as a substrate for sample preparation. The sample preparation device, shown in the image below, consist of three main parts: a buffer unit with four wells (for lysis, binding, and two wash buffers) (at the top), a sliding mixing unit (in the middle), and a detection unit (at the bottom). The device’s mixing unit aligns with the buffer unit to activate ball-based valves, enabling each solution to be released in sequence. This controlled flow concentrates viral RNA onto a paper pad in the detection unit. This paper pad allows us to efficiently enrich the virus’s genetic material from the sample. We amplify the collected RNA using a technique known as RT-LAMP (reverse transcription loop-mediated isothermal amplification), which achieves the similar level of sensitivity without the need of sophisticated thermal management required for PCR (polymerase chain reactions).

But the true simplicity lies in detecting the amplified RNA. Once the amplification process is complete, the result can be read using a colorimetric detection (a color change that’s visible to the naked eye) or real-time imaging setup that can quantify the viral load. Both methods require no specialized lab infrastructure, making this innovation a potential game-changer for decentralized, point-of-care HIV testing.

Unleashing the Potential for Broader Public Health Impact

Our results are, in a word, promising! Our test reaches sensitivity levels comparable to the gold-standard of NAT, detecting as few as 30 copies of HIV RNA per milliliter. Our platform is sensitive, specific, and crucially, portable. And because our method is selective, it can distinguish between HIV and other viruses such as hepatitis C virus.

The beauty of this platform, though, lies in its adaptability. With minimal adjustments, this same technology could be adapted for other infectious pathogens, making it a possible solution for public health challenges beyond HIV. Imagine a platform that is indispensable in settings with multiple infectious threats at once, from emerging viruses to persistent diseases in low resource communities.

Each diagnostic breakthrough is a step forward in the global fight against HIV, but as researchers, we’re aware that the path to the finish line is far from clear. Nevertheless, innovations like our device move the goalposts forward, especially for communities that have long been waiting for accessible, reliable tools.

We hope our work serves as a reminder of what science can achieve. Empowering communities with the tools to detect infections early brings us closer to universal access to treatment and an eventual end to the HIV/AIDS epidemic.