Editorial Feature

11 Year Old’s Carbon Nanotube Invention to Detect Lead in Water


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When 11-year-old Gitanjali Rao of Colorado learned about Flint Water Crisis, she began to research on the current methods to detect lead in water through various test strips. In an effort to improve the sensitivity of detecting contaminants in water at a reasonable price, Rao developed “Thethys,” a 3D printed carbon nanotube structure that is capable of detecting lead in water faster than any other techniques currently available on the market.

Lead Contamination in Water

In 2014, officials in Flint, Michigan switched their water supplier from Detroit Water and Sewerage Department (DWSD) to building and connecting their own pipeline to the Karegnondi Water Authority (KWA). This switch appeared to be an economically advantageous choice that would save the city approximately $200 million over a 25-year period.

However, in less than a month after the switch, Flint residents began to complain about the smell and color of the new water, which they also discovered to be 70% harder than what was expelled from their pervious water source. As these complaints continued to surface, officials discovered that the water not only contained varying concentrations of E. coli, total coliform bacteria and disinfection byproducts such as total trihalomethanes, but also dangerously high lead levels that measured to as high as 13,200 parts per billion (ppb)1.

Harmful Health Effects of Lead in Water

Young children, infants and fetuses are most vulnerable to the effects of lead, particularly when they are exposed to the heavy metal by ingestion. When lead contaminates drinking water sources and a child’s blood lead levels (BLL) measures around the acceptable baseline level set by the United States Centers for Disease Control (CDC) of 5 micrograms per deciliter, various physical and behavioral effects can occur, including learning disabilities, behavioral disorders, lower IQ, hyperactivity, slowed growth, hearing problems and anemia2. Adults exposed to lead through drinking water can also experience effects in their cardiovascular systems, such as high blood pressure or increased incidence of hypertension, lower kidney function and reproductive problems. While rare, extremely high levels of lead ingestion can cause seizures, comas and even death.

While the United States Environmental Protection Agency (EPA) claims that lead contaminated waters cannot allow the metal to penetrate the skin to cause any effects, many individuals who were exposed to such dangerously high levels of lead in their water supplies claimed to have an increased incidence in skin rashes.  

The Design and Efficacy of “Tethys”

Named after the Greek goddess of fresh water, the “Tethys” uses a disposable three-dimensional (3D) printed cartridge that contains a carbon nanotube sensor that is highly sensitive to changes in the flow of current. When the device is dipped into contaminated water, the atoms of the sensor react with lead molecules that are present within the water and cause a resistance to the flow of current in the nanotubes3. As the resistance of the flow increases, it is then detected by the nanotube sensor that transfers this data to a smartphone app for analysis.

Current testing methods to detect contamination in water supplies involve the use of multiple test strips that can cost anywhere from $15-30 per strip. Once the strip is tested, it is then sent to a laboratory that has the proper equipment that measures the exact concentration of contaminants present in the supply. To streamline this process, Rao’s invention provides immediate results without the high cost that is often associated with traditional testing procedures.

For her fascinating and versatile invention, Rao was named the Discovery Education 3M Young Scientist and awarded a $25,000 award. Additionally, Rao was also awarded a 3-month mentorship with Kathleen Shafer, a research specialist in plastics technologies, who expects the proposed sensor to eventually be available for commercial purchase once the sensor’s feasibility is optimized.

References:

  1. “Lead-Laced Water in Flint: A Step-By-Step Look At The Makings Of A Crisis” – National Public Radio, Inc.
  2. “Basic Information about Lead in Drinking Water” – United States Environmental Protection Agency
  3. “Meet the 11-year old who won a $25,000 science prize” – CNN

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