Figure 2

Microfluidic chip design. (a): Schematic diagram. The microfluidic chip had one outlet and two inlets for βHBA standard solution or serum sample and the detector mixture, respectively. The main channel of 200 μm wide and 60 μm deep consisted of a mixing channel, incubation channel and a sensing well. Hundreds of posts arranged in a zigzag line were designed in the mixing channel to enhance the mixing effect. A long pathway for liquid was designed for further mixing enhancement and incubation. The diameter of the sensing well was 2.5 mm, which was comparable to the sensing area of the Si photodiode. The flow was driven by the capillary forces. (b) The picture of the microfluidic chip filled with a blue dye for visualization.