Thermal Conductivity Detector for Gas-Chromatography: Acquisition System and Experimental Measurements

The aim of this paper is to present an acquisition system and experimental measurements of a new micromachined Thermal Conductivity Detector (mu TCD), applied downstream of a gas-chromatography (GC) system. We describe a simple and innovative electronics for sensor control and data acquisition, outlining its resistance control, native imbalance compensation and automatic gain control (AGC) algorithm. Measurements and sensitivity tests have been carried out by connecting our TCD and acquisition system downstream of the microfluidic section and GC column of a commercial GC system. Comparing the results with those of a complete commercial GC system we observed a similar response and noise. Sensitivity measurements on toluene masses gave very good results, having observed a sensitivity of 15.2 +/- 0.6 mu Vs/ng. This high sensitivity will enable the use of the mu TCD in many portable applications like in-line quality control, industrial security and safety. We also show the good operation of the AGC algorithm.