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  Micro Gas Chromatography

The objective of this research is to develop a highly sensitive, mechanically robust and mass producible gas micro-detector, designed for integration into a portable micro-gas chromatographic system capable of competing with the performance of traditionally laboratory instrumentation. The approach taken will be to optimize performance and sensitivity of the detector by modeling, analyzing and testing the different heat flux pathways from the active element of the detector. Furthermore, the modeling and testing will be performed to enable violent mechanical shocks and a wide range of thermal and chemical operating environments.

In the push for novel gas sensors and detection mechanisms, little effort has been put into enhancing thermal conductivity detectors, one of the oldest gas sensors. However, thermal conductivity detectors are uniquely suited for miniaturization, since they are sensitive to the concentration of substances within a mixture, not the total mass of a sample, a limitation of flame ionization detectors and mass spectrometers. Therefore, miniaturization of gas chromatographic systems employing thermal conductivity detectors can maintain functional sensitivity while processing smaller sample masses, while simultaneously reducing power consumption and increasing mechanical robustness.

The development of a highly sensitive, yet simple and robust detector, integrated into a miniaturized system will enable applied gas chromatography to make an impact on fields ranging from point of care health services and homeland security, to industry process control and geological exploration.

Representative Publications (#denotes graduate students/postdocs supervised by X. Zhang; *denotes corresponding author by X. Zhang; +denotes contributed equally.)

B.C. Kaanta#, A.J. Jonca#, H. Chen, and X. Zhang*, "Temperature Distribution on Thermal Conductivity Detectors for Flow Rate Insensitivity," Sensors and Actuators A: Physical, 2011, 167(2): 146-151. [DOI]

B.C. Kaanta#, H. Chen, and X. Zhang*, "Effect of Forced Convection on Thermal Distribution in Micro Thermal Conductivity Detectors," Journal of Micromechanics and Microengineering, 2011, 21(4): 045017(8pp). [DOI]

B.C. Kaanta#, H. Chen, and X. Zhang*, "Novel Device for Calibration-Free Flow Rate Measurements in Micro Gas Chromatographic Systems," Journal of Micromechanics and Microengineering, 2010, 20(9): 095034(7pp). [DOI]

B.C. Kaanta#, H. Chen, and X. Zhang*, "A Monolithically Fabricated Gas Chromatography Separation Column with an Integrated High Sensitivity Thermal Conductivity Detector," Journal of Micromechanics and Microengineering, 2010, 20(5): 055016(6pp). [DOI]

Ph.D. Dissertation

Bradley Kaanta, "MEMS Thermal Conductivity Sensor with Flow Rate Detection and Invariance for Gas Chromatography Systems," Ph.D. Dissertation, Boston University. (Advisor: Xin Zhang; January 2011)

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