Fluorescence microscopes uses fluorescence or phosphorescence instead of reflection and absorption used in the standard light microscope many know. Unlike light microscopy techniques fluorescence microscopy only allows observation of structures that have been labeled for fluorescence. For example, observing a tissue sample prepared with a fluorescent DNA stain only reveals the organisation of the DNA within the cells and nothing else of a cell's morphology.
Fluorescence microscopes are great instruments and widely used especially when particular structures are to be observed. However, as with most optical instruments they are anything but cheap and they are rather large. How great would it be to have one of those in a small portable format for a reasonable price? Maybe for a smartphone? Science fiction? Not anymore.
Researchers at the University of California, Los Angeles have developed a small, lightweight device that allows users to turn a smartphone into a fluorescence microscope that allowed the direct visualization of individual DNA molecules that were fluorescently labeled. This optical device was created on a 3D printer and includes an attachment that represents a high-contrast, dark-field imaging set-up using an inexpensive external lens, thin-film interference filters, a miniature dovetail stage and a laser diode that excites cellular structures labeled for fluorescence. An app connects the phone to the university's servers to measure the molecules, which are labeled and stretched on disposable chips that fit the device. The results can be seen on both the smartphone and external computers connected to the respective servers.
The researchers used the mobile phone platform to image single DNA molecules of various lengths to demonstrate a sizing accuracy of <1 kilobase-pairs (kbp) for 10 kbp and longer DNA samples imaged over a field-of-view of ∼2 sqmm. This is quite impressive for a prototype and what I find even more impressive are images that directly contrast the new platform and a benchtop fluorescence microscope (image on the right mobile phone, on the left benchtop instrument).
The ability to translate these and other existing microscopy and sensing techniques to field-portable, cost-effective and high-throughput instruments can make possible myriad new applications for point-of-care medicine and global health. The device could also be useful for research and education in developing countries or institutions with limited resources.
h/t Steve Borho