Water contaminated with mercury is an all too common reality around the world, while quickly and cheaply detecting the heavy metal remains a challenge. To better test for mercury by just about anyone anywhere, researchers at UCLA have developed a device that utilizes a smartphone’s camera and processing power to spot mercury ions at concentrations down to about 3.5 parts per billion.
The system requires mixing a water sample into a a disposable test tube containing a solution of gold nanoparticles and synthesized DNA strands that bind to mercury. The test tube is then positioned into the smartphone attachment where two separate LEDs, one at a wavelength of 523 nm and one at 625 nm, shine light on the mixture and the smartphone camera detects the reflected light signature of the mercury and gold nanoparticles clustering together.
The team has done an initial field study of the device, testing over fifty different water sources around California, and believes that screening for mercury using this technology can bring the cost down to around five cents per test.