Research ArticleDiagnostics

A digital microfluidic system for serological immunoassays in remote settings

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Science Translational Medicine  25 Apr 2018:
Vol. 10, Issue 438, eaar6076
DOI: 10.1126/scitranslmed.aar6076

A fluid transition into the field

Many point-of-care diagnostics rely on lateral flow assays or microfluidics; however, these methods generally cannot test multiple samples simultaneously. Ng et al. optimized inkjet-printed digital microfluidic (DMF) cartridges and a portable control system to perform serological immunoassays in remote settings. DMF devices use electrostatic forces to mix and separate reagents and samples in small droplets of fluids. The DMF system measured IgG antibodies for measles and rubella from human blood samples obtained from adults and children on-site in a refugee camp in Kenya. Four samples could be tested simultaneously, although DMF IgG detection was less sensitive and specific than laboratory-based ELISA testing of matched serum samples. The emergence of this field-compatible technology brings with it new tools for advancing global health.


Serosurveys are useful for assessing population susceptibility to vaccine-preventable disease outbreaks. Although at-risk populations in remote areas could benefit from this type of information, they face several logistical barriers to implementation, such as lack of access to centralized laboratories, cold storage, and transport of samples. We describe a potential solution: a compact and portable, field-deployable, point-of-care system relying on digital microfluidics that can rapidly test a small volume of capillary blood for disease-specific antibodies. This system uses inexpensive, inkjet-printed digital microfluidic cartridges together with an integrated instrument to perform enzyme-linked immunosorbent assays (ELISAs). We performed a field validation of the system’s analytical performance at Kakuma refugee camp, a remote setting in northwestern Kenya, where we tested children aged 9 to 59 months and caregivers for measles and rubella immunoglobulin G (IgG). The IgG assays were determined to have sensitivities of 86% [95% confidence interval (CI), 79 to 91% (measles)] and 81% [95% CI, 73 to 88% (rubella)] and specificities of 80% [95% CI, 49 to 94% (measles)] and 91% [95% CI, 76 to 97% (rubella)] (measles, n = 140; rubella, n = 135) compared with reference tests (measles IgG and rubella IgG ELISAs from Siemens Enzygnost) conducted in a centralized laboratory. These results demonstrate a potential role for this point-of-care system in global serological surveillance, particularly in remote areas with limited access to centralized laboratories.

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