The tool is able to provide accurate and reliable results in real-time rather than the two-to-five days required for existing processes that test infections and antibiotic susceptibility.
“Advances in lab-on-a-chip microfluidic technology are allowing us to build smaller and more intricate devices that, in the medical research space, can provide more information for health care practitioners while requiring less invasive sampling from patients,” explains Mohammad Zarifi, an assistant professor at UBC Okanagan.
According to health care statistics from 2017, every hour of delay in antibiotic treatment increases mortality rates by nearly eight per cent due to infection complications in the bloodstream.
Zarifi, and his research group in the School of Engineering’s Microelectronics and Advanced Sensors Laboratory, tested their device by tracking the amount of bacteria present in a variety of samples under various scenarios. The scenarios resembled those encountered in clinical microbiological laboratories.
By sending a microwave signal through the sample, the device quickly and accurately analyzes and then generates a profile of existing bacteria.
The diagnostic tool not only provides a rapid, label-free and contactless diagnostic tool for clinical analysis but it also goes further, says Zarifi.
“The device is able to rapidly detect bacteria and in addition, it screens the interaction of that bacteria with antibiotics,” he adds. “The combined results give health care practitioners more information than they currently have available, helping them move forward to determine accurate treatments.”
This biosensor, explains Zarifi is a significant step forward in improving the complex antibiotic susceptibility testing workflow and provides a rapid and automated detection of bacteria as well as screening the bacteria proliferation in response to antibiotics.
The research was published in the journal Nature Scientific Reports with financial support from CMC Microsystems and the Natural Sciences and Engineering Council of Canada.
Abstract
Sensitive, Real-time and Non-Intrusive Detection of Concentration and Growth of Pathogenic Bacteria using Microfluidic-Microwave Ring Resonator Biosensor
Infection diagnosis and antibiotic susceptibility testing (AST) are time-consuming and often laborious clinical practices. This paper presents a microwave-microfluidic biosensor for rapid, contactless and non-invasive device for testing the concentration and growth of Escherichia Coli (E. Coli) in medium solutions of different pH to increase the efficacy of clinical microbiology practices. The thin layer interface between the microfluidic channel and the microwave resonator significantly enhanced the detection sensitivity. The microfluidic chip, fabricated using standard soft lithography, was injected with bacterial samples and incorporated with a microwave microstrip ring resonator sensor with an operation frequency of 2.5 GHz and initial quality factor of 83 for detecting the concentration and growth of bacteria. The resonator had a coupling gap area on of 1.5 × 1.5 mm2 as of its sensitive region. The presence of different concentrations of bacteria in different pH solutions were detected via screening the changes in resonant amplitude and frequency responses of the microwave system. The sensor device demonstrated near immediate response to changes in the concentration of bacteria and maximum sensitivity of 3.4 MHz compared to a logarithm value of bacteria concentration. The minimum prepared optical transparency of bacteria was tested at an OD600 value of 0.003. The sensor’s resonant frequency and amplitude parameters were utilized to monitor bacteria growth during a 500-minute time frame, which demonstrated a stable response with respect to detecting the bacterial proliferation. A highly linear response was demonstrated for detecting bacteria concentration at various pH values. The growth of bacteria analyzed over the resonator showed an exponential growth curve with respect to time and concurred with the lag-log-stationary-death model of cell growth. This biosensor is one step forward to automate the complex AST workflow of clinical microbiology laboratories for rapid and automated detection of bacteria as well as screening the bacteria proliferation in response to antibiotics.