A Sticky Upgrade For Paper-Based Tests

Scientists have developed a method to test for metal ions in both liquid and solid samples using paper and adhesive tape.

AsianScientist (Dec. 8, 2017) – In a study published in ACS Applied Materials & Interfaces, scientists have invented an inexpensive paper- and tape-based test that can be used to detect metal ions in both liquid and solid samples.

Simple paper-strip testing has the potential to quickly detect chemicals found in water, as well as liquids in the environment and in biological samples. One of the best-known examples of a paper dipstick test is the home pregnancy test, which detects the presence of a particular hormone in urine. Pregnancy tests are known to be accurate, but many other paper-based sensors are not as reliable.

This is because liquid samples can cause the indicator ink to leach off the paper, or result in discoloration that may affect the accuracy of the readout. Current tests also do not handle solid samples well. When it comes to testing anything solid, such as food or soil, samples need to be processed into a liquid form first.

In this study, a team of researchers led by Professor Shen Wei at Monash University, Australia, has developed a way to make low cost, paper-based test strips more versatile and reliable for analyzing both liquid and solid samples. The researchers achieved this using a simple household repair item—adhesive tape.

The team drew chemical symbols onto the tape using indicator ‘inks’ that change color when they react with specific substances, such as copper and chromium. The low-cost sensor, which the researchers dubbed ‘chemical responsive adhesive tape,’ or CAT, changed color and revealed the chemical symbols in response to solid heavy metal salts in powder form. The tape was also able to indicate the presence of metal ions and proteins in solution.

Additionally, when paired with paper-based sensors, CAT could detect heavy metal ions in water without displacing the indicator ink. The researchers suggest that their invention will expand the possibilities of paper-based sensor applications, allowing even solids to be analyzed quickly.

The article can be found at: Tan et al. (2017) Low-Cost Chemical-Responsive Adhesive Sensing Chips.


Source: American Chemical Society.
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