Mobile phone based clinical microscopy for global health applications

Abstract

Light microscopy provides a simple, cost-effective, and vital method for the diagnosis and screening of hematologic and infectious diseases. In many regions of the world, however, the required equipment is either unavailable or insufficiently portable, and operators may not possess adequate training to make full use of the images obtained. Counterintuitively, these same regions are often well served by mobile phone networks, suggesting the possibility of leveraging portable, camera-enabled mobile phones for diagnostic imaging and telemedicine. Toward this end we have built a mobile phone-mounted light microscope and demonstrated its potential for clinical use by imaging P. falciparum-infected and sickle red blood cells in brightfield and M. tuberculosis-infected sputum samples in fluorescence with LED excitation. In all cases resolution exceeded that necessary to detect blood cell and microorganism morphology, and with the tuberculosis samples we took further advantage of the digitized images to demonstrate automated bacillus counting via image analysis software. We expect such a telemedicine system for global healthcare via mobile phone -- offering inexpensive brightfield and fluorescence microscopy integrated with automated image analysis -- to provide an important tool for disease diagnosis and screening, particularly in the developing world and rural areas where laboratory facilities are scarce but mobile phone infrastructure is extensive.

Figure 1. Mobile phone microscopy layout schematic, prototype, and sample images.

(a) Mobile phone microscopy optical layout for fluorescence imaging. The same apparatus was used for brightfield imaging, with the filters and LED removed. Components only required for fluorescence imaging are indicated by “fluo.” Not to scale. (b) A current prototype, with filters and LED installed, capable of fluorescence imaging. The objective is not visible because it is contained within the optical tubing, and the sample is mounted adjacent to the metallic focusing knob. (c) Brightfield image of 6 µm fluorescent beads. (d) Fluorescent images of beads shown in (c). The field-of-view projected onto the camera phone CMOS is outlined. Scales bars are 10 µm.

Figure 2. Mobile phone microscopy images of diseased blood smears.

(a) Thick smear of Giemsa-stained malaria-infected blood. (b) Thin smear of Giemsa-stained malaria-infected blood. (c) Sickle-cell anaemia blood smear. White arrows point to two sickled red blood cells. Scale bars are 10 µm.

Figure 3. Fluorescence mobile phone microscopy images of tuberculosis in sputum.

(a) Fluorescence image of Auramine O-stained TB sputum sample. (b) Enlarged view of two tuberculosis bacilli from red-outlined area in (a). (c) Automated counting of fluorescently-labeled tuberculosis bacilli; counted bacilli are numbered and set to red in the image. Scale bars in (a) and (c) are 10 µm, scale bar in (b) is 1 µm.