faculty

Professor Department of Chemistry and Department of Environmental Health Sciences, Director of Industrial Hygiene Program
Ph.D., University of California-Berkeley

Environmental Analytical Chemistry

Phone: (734) 936-0766
E-Mail:ezellers@umich.edu

In the area of chemical sensors, our group has focused primarily on microsensors that utilize surface-acoustic-wave propagation through small piezoelectric substrates, whose responses arise from changes of mass or elastic stiffness in deposited interfacial films. Complementary sensor technologies, such as chemiresistors, which respond to changes in the dielectric properties of the interface material, are also being developed. Investigations have involved the synthesis of novel chemically selective interface (coating) materials, elucidation of the mechanisms by which the interfacial films interact with gas-phase analytes, development of predictive sensor response models, chemometric pattern recognition methods and artificial neural networks to aid in decoding sensor array response patterns, and construction of practical sensor-based instrumentation. Integration of these sensors with other micromachined components to create miniaturized ("on-chip") analytical systems employing novel valve, pump, preconcentrator, separation, and sensor-array designs is also being actively explored through collaborations in the Center for Wireless Integrated Microsystems (www.eecs.umich.edu/wims).

Among the sensor interface materials examined are Au-thiolate nanoclusters, organometallic complexes capable of facile ligand-exchange reactions, electrically conducting polymers, side-chain liquid-crystalline polymers capable of subtle size/shape selectivity, and various functionalized isotropic polymers. We are also exploring new materials to serve as preconcentration media in micromachined heaters, including nanoscaled graphitic films, silsesquioxane derivatives, and metal-organic frameworks. Other collaborative engineering and materials development efforts are focused on microfabricated structures for particulate trapping, in-situ calibration, thermoelectric cooling, and tunable separations.

Dr. Zellers is a member of the executive committee of the NSF-funded Integrated Graduate Education and Research Training (IGERT) Program headquartered in the Chemistry Department a Task Leader in the NSF-funded Engineering Research Center on Wireless Integrated Microsystems headquartered in the Electrical Engineering and Computer Sciences Department; and Director of the Occupational Health and Industrial Hygiene Programs headquartered in the Department of Environmental Health Sciences.

REPRESENTATIVE PUBLICATIONS

1. C. J. Lu, J. Whiting, R. D. Sacks, and E. T. Zellers, "Portable GC with tunable retention and microsensor array detection for the determination of complex vapor mixtures," Anal. Chem . 75(6), 1400-1409 (2003).

2. M. D. Hsieh and E. T. Zellers, "Limits of recognition for simple vapor mixtures determined with a microsensor array," Anal. Chem . 76, 1885-1895 (2004).

3. W.C. Tian, H. K. L. Chan, C. -J. Lu , S . W. Pang, and E. T. Zellers, " Microfabricated multi-stage p reconcentrator-focuser for a micro gas chromatograph," Journal of Microelectromechanical Systems , 14, 498-507 (2005).

4. C.-J. Lu, W. H. Steinecker, W.-C. Tian, M. Agah, J. A. Potkay, M. C. Oborny, J. Nichols,   H. K. L. Chan, J. Driscoll, R. D. Sacks, S. W. Pang, K. D. Wise, E. T. Zellers, "First generation hybrid MEMS gas chromatograph," Lab On A Chip , 5, 1123-1131 (2005).

5. C.-J. Lu, C. Jin, and E. T. Zellers,   "Chamber evaluation of a portable GC with tunable retention and microsensor-array detection for indoor air quality monitoring," J. Environmental Monitoring, 8, 270-278 (2006).