Researchers have developed a new low-cost smartphone accessory that for the first time replicates all mechanical, optical, and electronic functions of a lab-based blood test for some sexually transmitted diseases (STDs) from a finger prick of blood in only 15 minutes. Results from a pilot test of the device were published in the journal Science Translational Medicine.

Samuel K. Sia, PhD, from Columbia University’s Fu Foundational School of Engineering and Applied Science, and colleagues designed the accessory (or dongle) that connects to a smartphone to perform a triplexed immunoassay for HIV antibody, treponemal-specific antibody for syphilis, and non-treponemal antibody for active syphilis infection. No immunoassays for these diseases are currently available on the market in a single test format. The dongle performs the enzyme-linked immunosorbent assay (ELISA) using only power from the smartphone; the low power consumption allows the accessory to be used in areas without widespread or reliable electricity.

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A pilot study by healthcare workers in Rwanda tested whole blood obtained via a finger prick from 96 patients who were enrolling into prevention-of-mother-to-child-transition clinics or voluntary counseling and testing centers. Workers were given 30 minutes of training on dongle use that included a user-friendly interface, step-by-step pictorial directions, built-in timers to alert the user to next steps, and records of test results for later review. The diagnostic results had sensitivity of 92–100% and specificity of 79–100%, which are consistent with laboratory-based HIV ELISA and rapid plasma regain. Patients preferred the dongle to laboratory-based tested by 97%, citing the convenience of fast results with a single finger prick.

Dr. Sia estimates that the dongle will have a manufacturing cost of $34, which is significantly lower than the typical $18,450 cost for ELISA equipment. Next steps include further studies in developing countries and exploring opportunities for use by patients in the United States.

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