A Microfabricated Diffusional Vapor Sampler with Integrated Thermal Desorption Heater

Research Trainee: Kathryn Sensenig, PhD Student, Dept. of Chemistry at the University of Michigan

Faculty Researcher: Edward T. Zellers, PhD, Professor of Environmental Health Sciences and Chemistry at the University of Michigan

The development of a passive microfabricated diffusional vapor sampler (μDVS) with integral thermal desorption heater, occupying a volume of ~0.15 cm3, is proposed. Advantage will be taken of the micron-scale dimensions of the device components to achieve high (pumpless) effective sampling rates, high preconcentration factors, and power-efficient desorption of ambient volatile organic vapors (VOCs). Performance will be assessed in light of theoretical models of diffusional transport and adsorption capacity. The device will be interfaced with a conventional photo-ionization detector as well as a microsensor array and subjected to chamber tests to document the quantitative capture, release, and detection of common indoor and workplace contaminants at ambient concentrations ranging from low-ppb to low-ppm with a duty cycle of ~1-15 minutes. Through this work, the feasibility of performing direct measurement of vapor exposures in occupational environments with such a microsystem will be demonstrated. Different, partially selective adsorbent materials will be tested to explore the possibility of using an array of samplers within a single module for broad-based vapor monitoring. If these preliminary tests are successful, this diffusive sampler design could be adapted for incorporation into the next prototype micro-gas chromatograph (μGC) being developed in an on-going parallel effort funded through the Michigan Center for Wireless Integrated Microsystems (WIMS) in which the PI and co-PI are involved. This research will address needs identified as NIOSH NORA research priorities in the areas of indoor environments, emerging technologies, and exposure assessment methods.