Microfluidic device and method for detecting an infected cell in a fluid sample

A method for detecting an immune cell comprising an internalized microbe in a fluid sample comprising the steps of:

• A. providing a microfluidic device comprising:
• i. an inlet to receive a fluid sample with an immune cell with an internalized microbe and an immune cell without an internalized microbe;
• ii. a curvilinear microchannel in fluid communication with the inlet, the curvilinear microchannel is configured in a loop concentrically surrounding the inlet, wherein at least a curve portion of the loop has a rectangular cross-section along a substantial portion of the length of the curved portion enabling the detection of the immune cell with an internalized microbe from the immune cell without an internalized microbe in the fluid sample through their differences in cell deformability, wherein the microchannel has an inner wall;
• and
• iii. a plurality of outlets in fluid connection with the curvilinear microchannel, wherein at least two of the outlets closest to the inner wall of the microchannel receive the immune cell with an internalized microbe;
• each of the outlets receive the immune cell without an internalized microbe,
• wherein the plurality of outlets is from about 2 outlets to about 20 outlets;
• B. introducing the fluid sample into the inlet at a predetermined flow rate of from about 1.3 ml/min to about 2.1 ml/min;
• or from about 1.5 ml/min to about 1.9 ml/min;
• or about 1.7 ml/min;
• C. individually collecting the output from the plurality of outlets;
• and
• D. quantifying a proportion of the immune cells with an internalized microbe in each of the outputs, thereby enabling determination of infection stage of the fluid sample;
• wherein the quantifying step comprises an optical imaging step.