A Dongle For Detecting HIV And Syphilis

Rapid, inexpensive, easy to use point-of-care (POC) diagnostic tests are critically important in stemming infectious diseases, particularly in developing countries. Researchers at Dr. Sam Sia’s Columbia University lab have invented a promising device that can detect both HIV and syphilis and have successfully piloted it in Rwanda.

The Columbia device pairs a microfluidic cassette dongle with a smartphone. Test reagents are preloaded into the cassette. A “one-push” vacuum, like a bulb on an old-fashioned blood pressure cuff, is used to fill the chamber of the cassette with a blood sample, and reduce the need for electricity. Further, the audio jack on a smartphone is used to power the dongle and for data transmission.

Step-by-step illustration of dongle testing. [Credit: Tassaneewan Laksanasopin]

A smartphone dongle for diagnosis of infectious diseases at the point of care

1. • Tassaneewan Laksanasopin1,*, 
   
   • Tiffany W. Guo1,*, 
   
   • Samiksha Nayak1, 
   
   • Archana A. Sridhara1, 
   
   • Shi Xie1, 
   
   • Owolabi O. Olowookere1, 
   
   • Paolo Cadinu1, 
   
   • Fanxing Meng1, 
   
   • Natalie H. Chee1, 
   
   • Jiyoon Kim1, 
   
   • Curtis D. Chin1, 
   
   • Elisaphane Munyazesa2, 
   
   • Placidie Mugwaneza3, 
   
   • Alex J. Rai4, 
   
   • Veronicah Mugisha2, 
   
   • Arnold R. Castro5, 
   
   • David Steinmiller6, 
   
   • Vincent Linder6, 
   
   • Jessica E. Justman7, 
   
   • Sabin Nsanzimana3 and 
   
   • Samuel K. Sia1,†
   
   
   
   • ↵†Corresponding author. E-mail: ss2735@columbia.edu
   
   
   Abstract

This work demonstrates that a full laboratory-quality immunoassay can be run on a smartphone accessory. This low-cost dongle replicates all mechanical, optical, and electronic functions of a laboratory-based enzyme-linked immunosorbent assay (ELISA) without requiring any stored energy; all necessary power is drawn from a smartphone. Rwandan health care workers used the dongle to test whole blood obtained via fingerprick from 96 patients enrolling into care at prevention of mother-to-child transmission clinics or voluntary counseling and testing centers. The dongle performed a triplexed immunoassay not currently available in a single test format: HIV antibody, treponemal-specific antibody for syphilis, and nontreponemal antibody for active syphilis infection. In a blinded experiment, health care workers obtained diagnostic results in 15 min from our triplex test that rivaled the gold standard of laboratory-based HIV ELISA and rapid plasma reagin (a screening test for syphilis), with sensitivity of 92 to 100% and specificity of 79 to 100%, consistent with needs of current clinical algorithms. Patient preference for the dongle was 97% compared to laboratory-based tests, with most pointing to the convenience of obtaining quick results with a single fingerprick. This work suggests that coupling microfluidics with recent advances in consumer electronics can make certain laboratory-based diagnostics accessible to almost any population with access to smartphones.