PhD Proposal Presentation

Milad Navaei

Thursday, December 4, 2014, 3:00 p.m.

Love Building, Conference Room 109

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 (Spelman college)

Integrated Micro- Gas Chromatography System for Detection of VOC gases

The focus of this work is on the design and micro-fabrication of a gas chromatography column with a novel two dimensional resistance heater for fast separation of Volatile Organic Compounds (VOC). 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 to prevent the rapid spread of the fungus agents. The major limitations of the current MEMS-GC systems are: 1. 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 areas occur 2. the time and power required 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: three and two 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-fusion bonding technique is developed to improve the sealing of the column; the proper sealing of the micro-machined GC column is a critical step in GC fabrication.– 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; Finally, a new temperature-programming heater 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 chromatograph is compared with a conventional GC column.