The detection of the volatile organic compounds (VOCs) in human breath can be analyzed by gas chromatograph (GC) as a non-invasive diagnosis for lung diseases. However, the gas concentration of the VOCs in human breath is low, approximating in the ppb to sub ppb range, and thus a gas preconcentrator (PCT) must be placed before a GC to collect and preconcentrate trace compounds. Early μPCTs using commercially available adsorbents and microheaters were demonstrated. However, the heating efficiency of the device is limited either by a large thermal mass or a poor heat transfer.

In this study, we present a gas PCT using a simple one-photomask micromachined process and the electroless gold deposition method to form the gold film, serving as a thin film microheater, on the inner surface of the microchannel . An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microfluidic channel followed by the electroless gold deposition. The developed gas PCT can be heated to >300℃ by applying a constant electrical power of ~5W with a heating rate of 60℃/sec.. Four suspected lung cancer biomarkers, acetone, benzene, toluene and xylene, are collected through the proposed gas PCTs and separated successfully using a 17-m-long gas chromatography (GC) column. Compared with previous works, the more simple fabrication process, more stable heating element, more uniform temperature distribution and more efficient heating rate of the micro gas preconcentrator are developeddemonstrated.