Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology

In this study, a simple process for fabricating a novel micromachined preconcentrator (μPCT) and a gas chromatographic separation column (μSC) for use in a micro gas chromatograph (μGC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μPCT and μSC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μPCT and μSC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μPCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s^-1. Repeatable thermal heating responses for μPCTs were achieved; good linearity (R ² > 0.9997) was attained at three heating rates for the temperature programme for the μSC (0.2, 0.5 and 1 °C s^-1). The volatile organic compounds (VOCs) toluene and m-xylene were concentrated over the μPCT by rapid thermal desorption (peak width of half height (PWHH) <1.5 s); preconcentration factors for both VOCs are >7900. The VOCs acetone, benzene, toluene, m-xylene and 1,3,5-trimethylbenzene were also separated on the μSC as evidenced by their different retention times (47-184 s).