Introducing samples into microfluidics by thermopneumatic suction system.

(A) Visible and thermal images of the microfluidic device during heating. The heater device was folded into square-wave-like shape and installed immediately under the suction chamber to effectively heat the air inside the chamber. The red and blue arrows indicate the blood cells and plasma, respectively. The chromaticity bar indicates the temperature from 26°C (room temperature) to 38°C. The system works effectively with relatively small variations in temperature. (B) Chart of temperature reduction inside the chamber, and six actual images inserted near the curves indicate the stages of separation. The chart starts from the cooling down (i.e., from 2 min). The whole-blood sample was sucked into the channel immediately after loading. At 30 s after loading, the sample reached the inlet of the filter trench and filled the entire trench at 6 min. At 8 min, the filtered plasma entered the detection zone, and biomarker examination could be executed immediately.