Electroosmotic flow driven microfluidic device for bacteria isolation using magnetic microbeads

Abstract

The presence of bacterial pathogens in water can lead to severe complications such as infection and food poisoning. This research proposes a point-of-care electroosmotic flow driven microfluidic device for rapid isolation and detection of E. coli in buffered solution (phosphate buffered saline solution). Fluorescent E. coli bound to magnetic microbeads were driven through the microfluidic device using both constant forward flow and periodic flow switching at concentrations ranging from 2 × 105 to 4 × 107 bacteria/mL. A calibration curve of fluorescent intensity as a function of bacteria concentration was created using both constant and switching flow, showing an increase in captured fluorescent pixel count as concentration increases. In addition, the use of the flow switching resulted in a significant increase in the capture efficiency of E. coli, with capture efficiencies up to 83% ± 8% as compared to the constant flow capture efficiencies (up to 39% ± 11%), with a sample size of 3 µL. These results demonstrate the improved performance associated with the use of the electroosmotic flow switching system in a point-of-care bacterial detection assay.

SpectIR-fluidics: completely customizable microfluidic cartridges for high sensitivity on-chip infrared spectroscopy with point-of-application studies on bacterial biofilms

“…This property is exploited in phosphate-buffered saline (PBS), 24 a popular biological buffer and molecular nutrient medium for microfluidic microbial studies. 25 The other solution was d -glucose, which is a common carbon source used in nutrient media. 26 d -Glucose is also found in a variety of biofluids in a range of concentrations, 27 and therefore, reducing its limit of detection is a longstanding goal that could expand clinical sensing applications involving urine, saliva, tears, sweat, and interstitial fluids.…”

Machined silicon traps for capturing novel bacterial communities and strainsin-situ

“…However, most microfluidic devices require sophisticated external instrumentation to be operated (active microfluidics) and, therefore, need to remove the sample from the original environment for processing, which potentially introduces sample bias and loss of diversity [4][5][6][7][8]. These active microfluidic techniques manipulate the particles' movement in real-time by using external forces, including electric fields [9-12], acoustic streaming [13], magnetic fields [14][15].…”

“…The communities of bacteria were easily removed from the device in the laboratory and analyzed.However, most microfluidic devices require sophisticated external instrumentation to be operated (active microfluidics) and, therefore, need to remove the sample from the original environment for processing, which potentially introduces sample bias and loss of diversity [4][5][6][7][8]. These active microfluidic techniques manipulate the particles' movement in real-time by using external forces, including electric fields [9-12], acoustic streaming [13], magnetic fields [14][15].A few passive sorting microfluidic devices have been demonstrated, but only a few do not disturb the environment. The iChip, for example, has been successfully used to cultivate many new species of bacteria, however, the sample must be collected by the user, diluted, the cells then placed inside of the isolation chambers, prior to placing it into the environment for nutrient exchange [16][17][18].…”

Microfluidic devices for studying bacterial taxis, drug testing and biofilm formation

“…C. A magnet was incorporated in the middle of the microfluidic device to attract magnetotactic bacteria that flowed through the channel. Adapted from (Miller et al., 2019 ). D. A microfluidic device with different regions where pressure could be applied.…”

“…In this way, the authors could isolate bacteria by passing them through the channel. They determined that switching the flow has the highest recruitment ratio (Miller et al ., 2019 ). Following a similar strategy, Chen and De La Fuente mimicked the natural environment of Xylella by applying a continuous flow in two parallel channels.…”