(A) Schematic illustration of the solenoid-embedded dual channel microfluidic sensor. The sensor is composed of two parallel channels: one for PGA sensing (light gray) and the other for control (dark gray). (B) Optical images of the solenoid chip filled with four different colors of inks. (C) Photograph of the capture area for magnetic immunocomplexes. Reprinted with permission from . Copyright 2015 American Chemical Society.