ReportsDiagnostics

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

See allHide authors and affiliations

Science Translational Medicine  04 Feb 2015:
Vol. 7, Issue 273, pp. 273re1
DOI: 10.1126/scitranslmed.aaa0056
  • Fig. 1. Overview of the dongle.

    (A) An image of the dongle with a microfluidic cassette connected to an iPod touch. (B) Schematic diagram of dongle highlighting a power-free vacuum generator using the audio jack connector for audio-based powering and frequency shift keying (FSK) data transmission to a smartphone or other smart-enabled device. Subfigure shows vacuum activation. (C) Left: A reagent cassette (top layer) that contains prestored reagents [washes (yellow) and silver A and B (blue and green)] and the test cassette (bottom layer) that contains five detection zones. Reagents are numbered in the order they flow through the test cassette. First, blood in the inlet flows through the channels, followed by gold-labeled antibodies resolubilized in 9 μl of 1% bovine serum albumin (BSA)/0.05% Tween 20 in phosphate-buffered saline (PBS) and two 2-μl 0.05% Tween 20 in PBS and four 2-μl water washes with air gaps in between. Once the venting port is closed, silver A and B mix and flow through the channels. Right: Sequence of flow through test cassette. From the inlet, fluids move through each detection zone sequentially, then flowing into a waste pad where blood sample and reagents are collected without any fluids exiting the chip. The power-free vacuum chamber connects to the cassette outlet, drawing fluids from the inlet toward the waste pad. (D) Comparison of features of conventional ELISA (6) versus the dongle in terms of methods and cost for each main module required for the diagnostic test.

  • Fig. 2. Assay and field readiness.

    (A) Schematic diagram of assay reactions: (1) Each zone is individually treated with proteins, or none for negative control (ctrl). (2) Whole-blood sample is flowed through the channel, followed by (3) gold (Au)–labeled antibodies (Ab), (4) washes, and (5) silver reagents. (B) Power consumption of dongle (black) and OD of the HIV zone (red) during the assay. (C) Serial dilution of RPR-positive (1:128) serum to mimic lower RPR titers. Data are averages ± SD (n = 3) and plotted with a linear regression fit and correlation. (D) Comparison of signal measurements obtained by addition of gold-labeled anti-human IgM (αhIgM) to gold-labeled anti-human IgG (αhIgG) and gold-labeled anti-human IgG alone as detection antibodies for negative, weak positive nontreponemal syphilis [RPR titer, 1:2 (R2)], and strong positive nontreponemal syphilis [RPR titer, 1:32 (R32)] plasma samples. Data are averages ± SD (n = 4 anti-human IgG; n = 3 anti-human IgG/anti-human IgM). (E) Comparison of signal from gold-labeled anti-human IgG and anti-human IgM antibodies lyophilized in a plastic antibody holder and freshly prepared in solution. Detection zones were functionalized with human IgG, human IgM, and rabbit anti-goat antibodies (positive ctrl). Data are averages ± SD (n = 3). n.s., not significant; Student’s t test.

  • Fig. 3. Field trial in Rwanda.

    (A) User interface on a smartphone shows steps of dongle operation: (1) enter “Patient ID”; (2) step-by-step pictorial instructions starting from sample collection; (3) assay waiting time and status; and (4) results for each disease marker in format of “Positive,” “Negative,” or “Indeterminate.” (B) Third-party field testing of the dongle using clinical fingerprick whole-blood specimens. A vertical scatterplot shows dongle device signal-to-cutoff ratios of samples positive (Pos) or negative (Neg) for HIV, treponemal (TP) syphilis, and nontreponemal (non-TP) syphilis as determined by gold standard tests (HIV ELISA, TPHA, and RPR). An ROC curve is provided for each disease marker. (C) Field testing by the development team of the dongle using venipuncture whole-blood specimens. Vertical scatterplots and ROC curves for each disease marker.

  • Fig. 4. Satisfaction survey from participants in this study.

Supplementary Materials

  • www.sciencetranslationalmedicine.org/cgi/content/full/7/273/273re1/DC1

    Materials and Methods

    Fig. S1. User-activated negative pressure–driven flow.

    Fig. S2. Smartphone-dongle interface and comparison with benchtop analyzer.

    Fig. S3. Stability of functionalized protein on microfluidic cassette.

    Fig. S4. Comparison of blocking agents.

    Fig. S5. Step-by-step illustration of dongle testing.

    Fig. S6. Optimization of dongle HIV assay using undiluted whole-blood samples.

    Fig. S7. Circuit diagram of dongle.

    Table S1. Bill of dongle materials and cost per component.

    Table S2. Raw data from field testing in three Rwandan clinics with reference results.

    Table S3. Raw data from venipuncture whole blood from Columbia University Medical Center (CUMC) with reference results for optimization of HIV antigen concentration.

  • Supplementary Material for:

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

    Tassaneewan Laksanasopin, Tiffany W. Guo, Samiksha Nayak, Archana A. Sridhara, Shi Xie, Owolabi O. Olowookere, Paolo Cadinu, Fanxing Meng, Natalie H. Chee, Jiyoon Kim, Curtis D. Chin, Elisaphane Munyazesa, Placidie Mugwaneza, Alex J. Rai, Veronicah Mugisha, Arnold R. Castro, David Steinmiller, Vincent Linder, Jessica E. Justman, Sabin Nsanzimana, Samuel K. Sia*

    *Corresponding author. E-mail: ss2735{at}columbia.edu

    Published 4 February 2015, Sci. Transl. Med. 7, 273re1 (2015)
    DOI: 10.1126/scitranslmed.aaa0056

    This PDF file includes:

    • Materials and Methods
    • Fig. S1. User-activated negative pressure–driven flow.
    • Fig. S2. Smartphone-dongle interface and comparison with benchtop analyzer.
    • Fig. S3. Stability of functionalized protein on microfluidic cassette.
    • Fig. S4. Comparison of blocking agents.
    • Fig. S5. Step-by-step illustration of dongle testing.
    • Fig. S6. Optimization of dongle HIV assay using undiluted whole-blood samples.
    • Fig. S7. Circuit diagram of dongle.
    • Table S1. Bill of dongle materials and cost per component.
    • Table S2. Raw data from field testing in three Rwandan clinics with reference results.
    • Table S3. Raw data from venipuncture whole blood from Columbia University Medical Center (CUMC) with reference results for optimization of HIV antigen concentration.

    [Download PDF]

Navigate This Article