Analytical validation of an ultra low-cost mobile phone microplate reader for infectious disease testing

Abstract

Most mobile health (mHealth) diagnostic devices for laboratory tests only analyze one sample at a time, which is not suitable for large volume serology testing, especially in low-resource settings with shortage of health professionals. In this study, we developed an ultra-low-cost clinically-accurate mobile phone microplate reader (mReader), and clinically validated this optical device for 12 infectious disease tests. The mReader optically reads 96 samples on a microplate at one time. 771 de-identified patient samples were tested for 12 serology assays for bacterial/viral infections. The mReader and the clinical instrument blindly read and analyzed all tests in parallel. The analytical accuracy and the diagnostic performance of the mReader were evaluated across the clinical reportable categories by comparison with clinical laboratorial testing results. The mReader exhibited 97.59-99.90% analytical accuracy and <5% coefficient of variation (CV). The positive percent agreement (PPA) in all 12 tests achieved 100%, negative percent agreement (NPA) was higher than 83% except for one test (42.86%), and overall percent agreement (OPA) ranged 89.33-100%. We envision the mReader can benefit underserved areas/populations and low-resource settings in rural clinics/hospitals at a low cost (~$50 USD) with clinical-level analytical quality. It has the potential to improve health access, speed up healthcare delivery, and reduce health disparities and education disparities by providing access to a low-cost spectrophotometer.

Keywords: Analytical validation; Infectious diseases; Microplate reader; Mobile health diagnostic device; Optical device; Serology tests.

Fig. 1.

(a) The 3D model and (b) the assembled setup of the mReader.

Fig. 2.

The linear correlation between O.D. read by the mReader and the DSX instrument for viral infections: (a) Varicella-zoster virus (VZV) with 142 samples, (b) Cytomegalovirus (CMV) with 124 samples, (c) Measles virus using 87 samples, (d) Mumps virus with 87 samples, (e) Herpes simplex virus type 1 (HSV-1) using 38 samples, and (f) Herpes simplex virus type 2 (HSV-2) with 30 samples, all including kit-derived and in-house control across clinical reportable range, respectively.

Fig. 3.

The linear correlation between O.D. read by the DSX instrument and mReader for the Epstein-Barr virus (EBV) panel: (a) IgM viral capsid antigen (CA) read 37 samples, (b) IgG CA read 78 samples, (c) IgG Epstein Barr nuclear antigen (EBNA) with 37 samples, and (d) IgG early antigen (EAD) using 37 samples, all including kit-derived and in-house control across clinical reportable range, respectively.

Fig. 4.

The linear correlation between O.D. read by the DSX instrument and mReader for bacterial infections: (a) Lyme disease with 179 samples, and (b) Helicobacter pylori infection with 43 samples, including kit-derived and in-house control across a wide concentration range, respectively.