The objective of this CAREER proposal is to develop a new gas chromatographic architecture on a credit-card-size platform, named "GC Matrix," aimed at highly efficient separation and detection of complex volatile mixtures (>100 compounds) in only a few seconds. The approach is to: 1) develop a predictable single-etch-step three-dimensional buried channel technique, 2) develop GC columns having on-chip heaters, temperature sensors, flow meters, and thermal conductivity gas detectors (TCD), and 3) integrate the columns into a matrix architecture with minimal dead volume and fluidic transfer lines and demonstrate the GC Matrix separation efficiency.
In the proposed GC matrix, once the sample is injected, it will be simultaneously analyzed in all rows of the matrix; however, each row is configured, based on the volatility range of the analytes, to separate only a subset of the mixture. The serially coupled MEMS columns in each row will have different stationary phases and can be temperature programmed independently, providing a high degree of flexibility to rapidly separate compounds within each subset based on their boiling points and polarities. Analyte identification will be performed by analyzing the separation results of each column intercepted from its on-chip TCD.
By involving industry in curriculum activities, creating a "Microsystems Laboratory" course, and establishing the High-School Microsystems Engineering Program (HMEP) through collaboration with VT's National Society of Black Engineers and IEEE's Teacher in Service Program, this proposal will help students discover the societal benefits of electrical engineering which is an important factor in their recruitment and retention in engineering.
The aim of the research has been the development of micro analytical chemistry instruments that can be used for fast analysis of gaseous samples in the environment based on gas chromatography principle. The research has resulted into new microchips that can separate and detect multi-component gas mixtures. Two different microsystems based detectors has been realized in this project. One is a micromachined thermal conductivity detector and the other is a helium discharge ionization gas detector. With just a few milliwatts of power, these detectors can sense the presence of few tens of picograms of analytes in the environment. When integrated with gas separation columns fabricated on chips, these detectors can be used for identifying multiple compounds present in real samples. The separation chips are long channels made on a silicon substrate and are fabricated using fabrication methods similar to those for microelectronics development. Moreover, a new gas separation architecture, Matrix GC, has been introduced in this project enabling the separation and analysis of complex gas mixtures in a minute or so. In this method, the sample is introduced into an array of short microGC columns coated with different stationary phases. Each row of this matrix is responsible for separation a subset of analytes based on their boiling points. The project while advancing research in microfabrication and micro analytical chemistry, has resulted in student training in advanced interdisciplinary environments to pursue academic and industry careers.
