An electronic-sensing & magnetic-modulation (ESMM) biosensor device and methods of using the same, where the device incorporates electrical, microfluidic, and magnetic subsystems. The device and methods of using such a device can be applied to high throughput point-of-care screening for the quantification and evaluation of a subject's immune response to pathogenic infections, which can be useful for: early diagnosis, stratifying high-risk subjects infected with a pathogen; and determining the status or effectiveness of a therapeutic response.