Duarte-Guevara wins at GYSS Singapore Challenge

President of Singapore Tony Tan recently presented ECE doctoral student Carlos Eduardo Duarte Guevara with an award for winning the Singapore National Research Foundation’s Singapore Challenge for research into detecting foodborne pathogens.

The annual conference, taking place during foundation’s Global Young Scientists Summit, invites 48 proposals, and considers eight finalists for its top $100,000 prize. Duarte-Guevara, researching his PhD under Bioengineering Department Head and ECE affiliate Rashid Bashir, is developing novel ways of using electronics to detect bacteria in food. 

“The current detection process uses culture-based techniques that are time consuming and resource intensive,” Duarte-Guevara said. “We are working on new tools to find bacteria much more quickly and in portable settings, so it fundamentally changes the way inspection services look for dangerous bacteria in a food supply.” 

In order to improve upon the process, Duarte-Guevara is specifically working on a way to detect pathogenic bacteria electronically using specially designed transistors, called ISFETS, or ion-sensitive field-effect transistors. His technique involves first breaking the food down into a solution using a chemical reagent.

He then adds DNA primers that identify specific genomes of target pathogens, along with an enzyme that will make trillions of DNA copies if the bacterium is present. If he’s testing for E. Coli, for example, he adds the primer that will look for E. Coli bacterial DNA and make copies of it.

The beauty of this process, Duarte-Guevara explains, is that the DNA amplification process only starts if the bacteria is present - if there is no E. Coli, then none is copied, but if there is some present, the enzymes will generate trillions of copies of its DNA to be detected.

He then separates the solutions, putting testing samples on a different areas of his detector chip, each area only a matter of micrometers wide. Each transistor on the detector chip examines the pH of the solution; changes in pH indicate the presence of copied bacterial DNA making the solution more acidic or basic.

“The advantage of using electronics is that transistors have the capability to conduct millions of processes in parallel,” Duarte-Guevara said. “This ability allows us to use each transistor to test for a different pathogen, potentially testing for millions of bacteria simultaneously. Once the sample preparation process has culminated and the sample is on the FET sensors, the detection process on the chip only takes about an hour.” 

The work itself, Duarte-Guevara said, is scientifically complete, and now the main efforts he’s undertaking involve making the process easy for labs to use. He’s developing the technique primarily with the U.S. Department of Agriculture in mind, and aims to start making chips with Taiwanese chip manufacturer TSMC on a larger scale in about 18 months. 

Despite the project’s utility, Duarte-Guevara admits to being amazed when hearing he’d won first place at the competition. He hadn’t initially planned on submitting his work, only doing so after hearing about the challenge through an invitation from the graduate college at Illinois. After his award was announced, a number of Singaporean institutions and companies approached Duarte-Guevara with offers to collaborate, including its agency for science, technology, and research, or A*STAR.

“I’m looking forward to putting the award money toward manufacturing the chips, and working with A*STAR on finding ways to streamline the detection process further," he said.