Spanish scientists wanting to save on lab costs managed to tinker a standard computer CD drive to act as a chemical testing platform currently capable of detecting the presence of various pesticides.
Maquieira [Angel Maquieira, Polytechnic University of Valencia -ed] and colleagues soldered two extra light sensors inside a CD player, and used software to control the way the device “plays” a disk.
The first sensor identifies the sector of a disk containing a sample using black marks on the edge of the disk. The second analyses the sample itself, measuring the amount of laser light that is able to pass through the disk. Ordinary disks normally reflect around 30% of the laser beam onto the reading head, with the rest passing through.
In experiments, the researchers used their modified drive to detect traces of three different pesticides. A sample — half a millimetre across on a disk — was treated normally, using a set of reactions that produce an amount of dye or silver that is inversely proportional to the amount of pesticide in the sample.
The amount of laser light that passed through the disk to the second sensor indicated the levels of dye or silver. The modified drive was thus able to detect levels of pesticide as low as 0.02 micrograms per litre.
Although the hacked device lags behind the performance of specialised [sic] machines, it is accurate enough for many lab tasks, the team says.
The team expects better results once the next generation of DVD players, working at higher laser frequencies, become more available and cheaper.
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