Origami paper folding has long been a traditional art form, but now researchers at the University of Texas at Austin have been inspired to use paper folding as a way to test for diseases. The idea expands on existing paper sensor tests, but the folding allows it to detect more complex substances and diseases.
It works on the principle of home pregnancy tests — a water resistant substance such as wax will channel the fluid to be tested into an area on the paper that contains a reagent. The reagent is activated if the sample contains whatever is being tested for.
Why origami? It's a cheap and easy way to create the 3D paper sensors that can operate with more complexity for diseases such as malaria or HIV, but over a smaller surface area. The tests can be printed using a regular printer, and for the cost of a handful of pennies.
Chemistry professor Richard Crooks built the sensor with doctoral student Hong Liu. The inspiration for the Paper Analytical Device (which they dubbed the oPAD) came to Liu when reading a paper on the first 3D microfluidic paper sensor that was created by Harvard Chemist George Whitesides.
Whitesides created his 3D model with the same kind of treated paper, but used laser cutting and tape to stick his models together. Liu reasoned the origami lessons he had as child has the same effect of creating 3D models but without the hassle. Instead, the time-honored technique of folding and pressure creates the structure.
The last piece of the puzzle for Cook and Liu was simply to make sure the various reagents that respond to various diseases worked on the paper. Biomarkers already exist that identify complex diseases such as HIV or malaria; it's what enables doctors to test for them in the lab. It's these biomarkers that reacted to the paper treated with the various reagents.
Being able to take tests out of the lab and putting it in the hands of ordinary people could be invaluable to public health in the developing world. Many towns or villages might not have the money or resources for lab testing, or for transporting samples to the nearest place that does.
And it was this need to provide a resource for the underserved that motivated the duo. In a press release, Dr. Cook said, "This is about medicine for everybody."
"Anybody can fold them up," says Crooks. "You don't need a specialist, so you could easily imagine an NGO with some volunteers folding these things up and passing them out. They're easy to produce, so the production could be shifted to the clientele as well. They don't need to be made in the developed world."
The team is also experimenting with adding a cheap battery to the sensor that would power tests that require electricity.