Plastic Chip Can Diagnose HIV and Other Conditions


A small plastic chip that costs no more than 10 cents to make can accurately diagnose HIV and syphilis in about 15 minutes.

While rapid diagnostic tests for HIV and other infections already exist, they are not used in poor areas around the world due to complicated instructions and high prices. Many health clinics and even city hospitals in Africa must send out blood samples to a national laboratory for processing that takes days or weeks to complete. Also, this process is even more difficult for people in poor, rural areas that may travel days to reach clinics and are unlikely to return for their results. Hopefully, this will all be made easier thanks to a new development at Columbia University.

A small plastic chip that costs no more than 10 cents to make can accurately diagnose HIV and syphilis in about 15 minutes. The chip uses microfluidics and contains small wafers that precisely manipulate nanoliter volumes of fluid in order to carry out a sequence of chemical reactions. The system was designed to be used in resource-poor settings, according to Samuel Sia and the collaborators who developed the new technology. With Sia’s chip, additional tests, such as for hepatitis or malaria, can be added to the chip without greatly raising the price.

Preliminary field tests in Kigali, Rwanda showed that the chip works as well as traditional laboratory-based HIV diagnostics. When the device was used to test for HIV and HIV and syphilis in combination, it detected 100 percent of cases, with a false positive rate of about 4 to 6 percent — equal to standard laboratory tests. As many as 8 percent of women in Kigali are HIV positive and with Sia’s chip, they can be diagnosed much faster than the traditional analysis of blood samples in outside labs.

Sia’s main focus for the chip is to be used in prenatal clinics in Africa stating, “If you catch the disease in the mothers, you can prevent transmissions to newborns, increasing clinical impact.” According to the research, syphilis testing in mothers and pregnant women could reduce the number of years lost due to ill health, disability, or early death by 200,000 in Rwanda.

Still, in order for their dreams to be realized, Sia and his collaborators must find funding to develop the STD device into a commercial product. The Gates Foundation declined to fund the next step in development even though research showed that STD testing was the optimal market to apply the technology.

Around the Web

A Quick, Cheap Diagnostic Test for HIV and Other Infections [Technology Review]

Microfluidics-based Diagnostics of Infectious Diseases in the Developing World [Nature Medicine]

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