The schematic of the μGC system.
Fabrication process of the μGC column: (a) a silicon wafer with 200 nm aluminum layer, (b) deposition of a layer of 400 nm silicon nitride on the backside of the silicon wafer, (c) positive photoresist spin coating and patterning on the surface of aluminum film, (d) aluminum etching, (e) DRIE based anisotropic etch of silicon, (f) the residual aluminum etching and Cr/Pt deposition and patterning on the backside of the silicon wafer, (g) Cr/Pt deposition and patterning on the backside of the glass wafer, (h) alignment and bonding of the glass wafer with the Si wafer.
(a) and (b) The micro heaters and temperature sensors on the surface and backside of the μGC column, respectively (the length and the width of the whole GC column are 35 mm and 35 mm, respectively).
Fabrication flow process for micro TCD: (a) a Si wafer with 15 μm diffused silicon layer and 400 nm silicon nitride layer, (b) Pt/Cr deposition and patterning, (c) positive photoresist spin coating and patterning, (d) RIE based isotropic etch of the silicon nitride film and DRIE based anisotropic etch of the diffused silicon film, (e) isotropic etch of Si, (f) Au/Cr deposition and patterning, (g) glass channel etching, (h) the residual Au etching, (i) alignment and bonding of the glass wafer with the Si wafer.
(a) The circuit schematic of the conventional μTCD, (b) the circuit schematic of the proposed μTCD, (c) photograph of the proposed μTCD (the length and width of the thermistors are 1.5 mm and 250 μm, respectively. The width and length of the whole μTCD are 25 mm and 40 mm, respectively).
The temperature distribution on the thermistor when the gas mixture (500 ppm benzene mixed in H2) with different velocities passed over.
The separation and detection of benzene, toluene, and styrene using the proposed μGC system at a velocity of 2 sccm.
Three-cycle experiments were conducted at the same condition using the proposed μGC system.
The relationship between the peak height and concentrations of the component toluene.
The detection of the benzene, toluene, and styrene using the proposed μGC system, sample volume of 500 μl at a concentration of 10 ppm. The velocity is 2 sccm.
The maximum temperature value of the thermistors when three different gas mixtures passed over the thermistors at a velocity from 1 sccm to 10 sccm, respectively.
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