London, Sept 24 : You can now create your own lab-on-a-chip device by just writing on a piece of paper. All you need is the right paper, ink, and sunlight to create a microfluidic device that can not only test water quality but identify pathogens also.
The new method, developed by George Whitesides and colleagues at Harvard, could help developing countries access the latest lab techniques.
The researchers have found that the pores naturally present in paper can carry liquids just like standard chips.
In order to make impermeable "walls" to confine the fluids into narrow channels, they use a polymer liquid that sets hard when exposed to UV light called photoresist, which is used to etch designs onto silicon chips.
For making the paper chips, the researchers soaked a piece of normal office paper in photoresist.
Later, they covered one side of the paper with transparency, and then used a pen to draw the desired pattern of channels on top.
On exposure to sunlight, the photoresist set hard, other than the area of the paper that was masked beneath the inked-on pattern.
The team later peeled the transparency off, and quickly washed the paper to remove any still-liquid photoresist.
Once dried, the final product came out to be a sheet of impermeable paper with a tiny network of permeable channels embedded within it, or a microfluidic device.
While drawing onto the transparency by hand is not very precise, but Whitesides claimed that the designs could simply be printed onto the transparency using an inkjet printer.
"Paper-based microfluidic devices probably won't be sensitive enough to detect every disease, but they are sensitive enough for many useful applications," New Scientist magazine quoted Andres Martinez, one of Whitesides' colleagues, as saying.