Pathogenic microorganisms threaten the health of the human race. An example is the bacteria that cause food poisoning. In developing countries, food poisoning caused by pathogenic bacteria such as E.coli or salmonellae poses serious social problems. The Smart Materials & Sensors Laboratory directed by professor Sangmin Jeon at the Department of Chemical Engineering, POSTECH, as its name indicates, leverages intelligent materials and cutting-edge sensors to study future green technology in addition the detection of bacteria that poison food.

In the past, it was difficult to detect such poisoning bacteria without first cultivating it for at least two to three days. So it was almost impossible to identify the cause of the food poisoning before people got sick, making prevention virtually impossible.

With the help of magnetic nanoparticles, the Smart Materials & Sensors Laboratory developed diagnostic technology capable of confirming whether a food contained poisonous bacteria without the culture process. These micro-sized particles, functionalized with antibodies that only react to food poisoning bacteria, work like a magnet to attract and detect it. The Lab also developed technology to collect food poisoning bacteria that exist in traces in things like milk and the liquid in kimchi. These technologies allow us to identify the bacteria in just 20 minutes or less including pre-enrichment step. In fact, the Lab holds the world’s record for the fastest detection of food poisoning bacteria.

Preventive diagnostics plays a pivotal role in treating myocardial infarction. The Smart Materials and Sensors Lab has also developed a technology to detect TnI proteins, a biomarker of myocardial infarction, using platinum nanoparticles in 10 minutes.

With the advent of COVID-19, the demand for disposable face masks has dramatically increased, and this prompted the Lab to create a solution in response. Currently, most disposable face masks are made from a polypropylene-based microfibers with a diameter of >10 micrometers. The Lab has reduced this thickness to the nanometer level to provide a much more breathable and comfortable fit. When the fiber diameter decreases to the mean free path of air (∼70 nm), the air flow slips around the nanofiber and the drag force decreases, reducing the pressure drop.

The Lab has succeeded in manufacturing masks that are durable, washable, and reusable. Washing with water eliminates the face mask’s electrostatic attraction to viruses or particulate matters. Researchers at the Lab noticed that electrostatic charges on the face mask could be recovered by contact electrification, i.e., by simply rubbing them against a Teflon cloth. The face masks were found to be reused dozens of times after the simple washing and regeneration steps.

“As global warming accelerates, this may trigger the melting of frozen layers of Antarctica or Siberia, which will expose us to microbes that we have never experienced before”, professor Jeon commented, adding “We will continue to explore technology that promotes the safety and health of all people”.