Optofluidic Fluorescent Imaging Cytometry on a Cell Phone

Electrical Engineering Department, University of California, Los Angeles, Los Angeles, California 90095, USA.
Analytical Chemistry (Impact Factor: 5.64). 08/2011; 83(17):6641-7. DOI: 10.1021/ac201587a
Source: PubMed


Fluorescent microscopy and flow cytometry are widely used tools in biomedical sciences. Cost-effective translation of these technologies to remote and resource-limited environments could create new opportunities especially for telemedicine applications. Toward this direction, here we demonstrate the integration of imaging cytometry and fluorescent microscopy on a cell phone using a compact, lightweight, and cost-effective optofluidic attachment. In this cell-phone-based optofluidic imaging cytometry platform, fluorescently labeled particles or cells of interest are continuously delivered to our imaging volume through a disposable microfluidic channel that is positioned above the existing camera unit of the cell phone. The same microfluidic device also acts as a multilayered optofluidic waveguide and efficiently guides our excitation light, which is butt-coupled from the side facets of our microfluidic channel using inexpensive light-emitting diodes. Since the excitation of the sample volume occurs through guided waves that propagate perpendicular to the detection path, our cell-phone camera can record fluorescent movies of the specimens as they are flowing through the microchannel. The digital frames of these fluorescent movies are then rapidly processed to quantify the count and the density of the labeled particles/cells within the target solution of interest. We tested the performance of our cell-phone-based imaging cytometer by measuring the density of white blood cells in human blood samples, which provided a decent match to a commercially available hematology analyzer. We further characterized the imaging quality of the same platform to demonstrate a spatial resolution of ~2 μm. This cell-phone-enabled optofluidic imaging flow cytometer could especially be useful for rapid and sensitive imaging of bodily fluids for conducting various cell counts (e.g., toward monitoring of HIV+ patients) or rare cell analysis as well as for screening of water quality in remote and resource-poor settings.

    • "Also, the associated holographic imaging requires standard images to be reconstructed from captured fringe patterns. The off-chip clip-on approach requires additional hardware attachments to be mounted on the cellphone (Breslauer et al., 2009; Zhu et al., 2011b; Arpa et al., 2012). However, due to differences in dimensions of cellphones, clip-on attachments may be model-specific (Arpa et al., 2012). "
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    • "Hence, exploiting the existing mobile phone infrastructure to monitor health conditions and the environment will accelerate the efforts toward diagnostics, as well as low-cost healthcare for existing and emerging diseases. The use of smartphone cameras has been suggested for diagnostic applications in dermatology [3], microscopy [4] [5] [6], ophthalmology [7], chemical analyses [8] [9] and paper-based microfluidic devices [10] [11] [12]. Smartphone cameras have standardization challenges in optical analysis of colorimetric assays; integrated color balancing functions of camera phones are optimized for photography in bright ambient light. "
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    • "Some groups have sought to lower the cost of the optical instrumentation by using common tools such as cell phone cameras and inexpensive miniaturized optics (Mostafalu and Sonkusale, 2013). Ozcan, for example, has demonstrated a handheld cell phone based flow cytometer (Zhu et al., 2011). Demirci and coworkers demonstrated a lenseless method for counting cells captured on a surface (Moon et al., 2009). "
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