DVD Drive + Ingenuity = Scanning Microscope

It is not everyday that brilliant lateral thinking can work magic and convert everyday objects into exotic instruments. Now such news comes out of the research labs of the School of Biotechnology at KTH Royal Institute of Technology in Stockholm, Sweden. And the icing on the cake is the cheap diagnostics it will augur in for HIV patients.

Early diagnosis of HIV infection is a key factor in successful treatment, and this depends on a reliable blood test. An established test for HIV is to measure the population of CD4+ T-helper cells - white blood cells with a key role in the body's immune system. Currently Flow Cytometry has been the method of choice for monitoring the number of these cells in a blood sample. But it is an expensive (upwards of $ 30,000) and relatively complex test, requiring lab facilities and trained personnel.

Now Dr Aman Russom, senior lecturer at the School of Biotechnology at KTH Royal Institute of Technology, has taken the ubiquitous (and cheap!) DVD drive for computers and, with just a few 'tweaks', converted it into a scanning laser microscope! The breakthrough 'Lab-on-DVD' technology has created the possibility of an inexpensive and simple-to-use tool that could have far-reaching benefits in health care in the developing world. "With an ordinary DVD player, we have created a cheap (less than $ 200) analytical tool for visualizing DNA, RNA, proteins and even entire cells," said Dr Russom.

The CD and DVD drives, devices of choice for high volume data storage in computers, have built-in high-precision laser optics and servo mechanisms. Dr Russom has now integrated the cheap optics of DVD drives with centrifugal microfluidics to come up with an accurate analytical platform.

The  blood sample is placed on a disposable polymer disk that fits into a standard DVD drive. Each disk is built from two half-disk substrates--the bottom portion with all the operational information required to allow the disc to be read by a standard DVD drive, while the top half-disk contains fluidic microchannels pre-treated to promote attachment of the cells of interest to the channel walls. The standard photodetector is complemented by another one on the opposite side of the disk. This allows a 2D image of particulates on the surface of the DVD channels to be built up by tracking changes in the absorbency and light-scattering observed. The proof-of-concept system demonstrated the specific detection of CD4+ cells direct from whole blood, with single-cell resolution images.

The KTH system is capable of imaging down to one micron, a figure dependent on the drive's optical specifications and the detection layer of the DVD disc, in which the linear distance between each spiral of the tracking path is 0.74 microns. The use of Blu-ray drives could enhance the resolution further, thanks to the shorter wavelength of the blue laser.

"The low cost of the technology and portability makes it suitable as a diagnostic and analytical tool in clinical practice close to the patient," Russom says. "And because it delivers extremely fast analysis, the patient ... can get [results] right on the first visit to a doctor."

The development is sure to warm the hearts of the original designers of the CD/DVD drive, seeing their 'baby' take a 'side-step'  to be transformed into a scanning laser microscope!

Explore more at:
http://www.kth.se/en/aktuellt/nyheter/dvd-lasaren-gor-comeback-som-hiv-testare-1.380911

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