MEMS-Based Volatile Organic Compound Monitor

Boston MicroSystems, Inc. (BMS), proposes to develop a MicroElectroMechanical System (MEMS) based volatile organic compound (VOC) monitor by integrating analyte-specific polymer films with SiC-AlN microresonators. In this research project, BMS and the Naval Research Laboratory will integrate microresonators and polymer films with functional groups sensitive to aromatic compounds (e.g., benzene and toluene); halogenated hydrocarbons (e.g., methylene chloride); and aromatic alcohols (e.g., phenols and catechols). When exposed to hazardous air pollutants, the polymer films absorb the vapors, increasing their mass and resulting in a shift in the resonant frequency that is proportional to the pollutant concentration. The proposed MEMS-based sensor system is compact and robust, and has low cost and power requirements, and high sensitivity. By using an array with multiple sensors, each with high sensitivity to a particular pollutant, a high selectivity is achieved. The fully functional multichannel monitor is anticipated to be a battery-powered instrument consisting of a microresonator array, drive/sense electronics, rechargeable power supply, visual display, self-test, data storage, and an interface for data downloading. The proposed volatile organic monitor will provide a compact handheld or remotely operated instrument that enables rapid, real-time, low-cost measurement of multiple pollutant gases for industrial applications as well as for U.S. Environmental Protection Agency field agents. Primary applications include: (1) emissions monitoring in smokestacks and exhaust streams of chemical, pharmaceutical, and power-generating plants and refineries; (2) leak detection and process control near industrial machinery and processes with potential hazardous emissions; (3) monitoring a wide range of source locations in and around industrial facilities, as "residual risk fenceline monitors"; and (4) toxic dump sites. Other commercial applications include: (1) measuring VOC and hazardous air pollutant emissions from thin-film radiation-cured coating processes; (2) air quality control in buildings and sensors coupled with heating, ventilation, and air conditioning systems ("sick building syndrome"); and (3) air quality testing in confined chambers, tunnels, and mines.