Low-cost sensor can diagnose bacterial infections by odor

April 28, 2011
Sensor Dish

Colorimetric sensor array in a Petri dish for culturing bacteria (credit: K. S. Suslick)

Researchers at the University of Illinois have demonstrated a quick, simple method to identify infectious bacteria by smell, using a low-cost array of printed pigments as a chemical sensor.

Using an array of 36 cross-reactive pigment dots that change color when they sense chemicals in the air (an “artificial nose”), the researchers spread blood samples on Petri dishes of a standard growth gel. They attached an array to the inside of the lid of each dish and then inverted the dishes onto an ordinary flatbed scanner. Every 30 minutes, they scanned the arrays and recorded the color changes in each dot. The pattern of color change over time was unique to each bacterium in the gel.

Within a few hours, the array confirmed the presence of bacteria and identified a specific species and strain of bacterium. The array also identified antibiotic resistance, a key factor in treatment decisions.

Sensor Bacteria

The color changes of the sensor array show what kind of bacteria is growing and if they are antibiotic- resistant (credit: K. S. Suslick)

Given their broad sensitivity, the chemical-sensing arrays also could enable breath diagnosis for a number of conditions, the researchers said. Medical researchers at other institutions have already performed studies using these arrays to diagnose sinus infections and screen for lung cancer.

Ref.: James R. Carey & Kenneth S. Suslick et al., Rapid Identification of Bacteria with a Disposable Colorimetric Sensing Array, April 27 online edition, JACS