Over the past decade, many researchers have been working on small, portable diagnostic devices based on chemical reactions that occur on paper strips. Many of these tests make use of lateral flow technology, which is the same approach used in home pregnancy tests.
Despite these efforts, such tests have not been widely deployed. One obstacle is that many of these devices are not designed with large-scale manufacturability in mind. Another is that companies may not be interested in mass-producing a diagnostic for a disease that doesn't affect a large number of people.
A kit was developed consisting of modular, plug-and-play components that can be put together to generate exactly what the user needs. About 40 different building blocks were created that lab workers around the world could easily assemble on their own, just as people began assembling their own radios and other electronic devices from commercially available electronic “breadboards” in the 1970s. In this case, the components consist of a sheet of paper or glass fiber sandwiched between a plastic or metal block and a glass cover.
The blocks, which are about half an inch on each edge, can snap together along any edge. Some of the blocks contain channels for samples to flow straight through, some have turns, and some can receive a sample from a pipette or mix multiple reagents together.
The blocks can also perform different biochemical functions. Many contain antibodies that can detect a specific molecule in a blood or urine sample. Those antibodies are attached to nanoparticles that change color when the target molecule is present, indicating a positive result. The blocks can be aligned in different ways, allowing the user to create diagnostics based on one reaction or a series of reactions. In one example, the researchers combined blocks that detect three different molecules to create a test for isonicotinic acid, which can reveal whether tuberculosis patients are taking their medication.
Using this system, called Ampli blocks, researchers are working on devices to detect cancer as well as Zika virus and other infectious diseases. The blocks are inexpensive, costing about 6 cents for four blocks, and they do not require refrigeration or special handling, making them appealing for use in the developing world.
The blocks are color-coded by function, making it easier to assemble predesigned devices using instructions that will be put online. Users also will be able to develop and contribute their own specifications to the online guide. Tests are being developed for human papilloma virus (HPV), malaria, and Lyme disease, among others. Blocks would be able to synthesize useful compounds, including drugs, as well as incorporate electrical components such as LEDs.
The ultimate goal is to get the technology into the hands of small labs in both industrialized and developing countries so they can create their own diagnostics. The devices have been sent to labs in Chile and Nicaragua, where they have been used to develop devices to monitor patient adherence to TB treatment, and to test for a genetic variant that makes malaria more difficult to treat.