SUBJECT: Ph.D. Proposal Presentation
   
BY: Milad Navaei
   
TIME: Thursday, December 4, 2014, 3:00 p.m.
   
PLACE: Love Building, 109
   
TITLE: Integrated Micro-Gas Chromatography System for Detection of VOC Gases
   
COMMITTEE: Dr. Peter Hesketh,, Chair (ME)
Dr. Todd Sulchek (ME)
Dr. Mostafa Ghiaasiaan (ME)
Dr. Albert Frazier (ECE)
Dr. Oliver Brand (ECE)
Dr. Jean-Marie Dimanja (Spelmen)
 

SUMMARY

The focus of this work is on design and micro-fabrication of a gas chromatography column with a novel two dimensional resistance heater for fast separation of chemical compounds. A new bonding technique is developed for proper sealing of the column. These features enable the MEMS-GC column to perform live and fast separation of the VOC gases released by pathogenic species of Armelaria fungus hence prevent the rapid spread of the fungus agents. The major limitations of the current MEMS-GC systems are: 1. current direct fusion bonding of silicon to silicon is not an effective technique for proper bonding of a high density micro-machined surface such as the GC column. This technique requires very smooth and clean surfaces otherwise small voids and unbonded area occurs 2. the time and power require to ramp and sustain the column’s temperature are very high for the current resistance heaters. In this work, three enabling designs and micro-fabrication techniques are developed and validated: 3 and 2 meters long circular GC columns are fabricated – The aim is to design and perform both analytical and experimental validation of all silicon gas chromatograph (GC) System for high resolution separation of compounds with a gas inlet in the center and an outlet on the side. Column separation performance is first studied as a function of the length of the column and further investigated for different widths by a numerical analysis, design and experimental validation follow. A gold eutectic bonding technique is developed to improve the sealing of the column– The aim is to create a fabrication process for proper sealing of the GC columns using a gold eutectic bonding technique for silicon silicon bonding; the proper sealing of the micro-machined GC column is a critical step in GC fabrication. Finally, a new temperature controlling system is developed to generate temperature gradients along the length of the column to refocus eluding bands and counteract the part of the chromatographic band spreading. Both analytical and experimental validation on the temperature gradient along the column and isothermal temperature are performed. In order to demonstrate the biological utility, the GC column is integrated into a portable GC system and the separation data is compared with a conventional GC column.