Exposure to particulate air pollutants is associated with cardiovascular disease, asthma, lung cancer, and other illnesses. In the United States the CDC estimates that asthma costs $20 billion annually in medical care, lost workdays, and early deaths. However, due to the complexity of the environmental exposure mechanisms, there remains a degree of uncertainty concerning disease etiology. Wearable and highly-sensitive particulate sensors could help further elucidate the linkages between disease and particulate exposure. In this Small Business Innovation Research Phase 2 project Aerodyne Microsystems Inc. (AMI) will investigate the feasibility of a miniaturized, battery-powered, and inexpensive sensor for real-time monitoring of exposure to airborne particulate matter (PM) from 2.5 um to ultrafine. The system employs the thermophoretic deposition of particulates from a sample air stream onto a thin-film bulk acoustic wave resonator (FBAR), and determines the PM mass deposited by measuring the frequency shift of oscillation. Incorporation of micromachined-electromechanical-system (MEMS) technologies allows unprecedented reduction in power consumption, cost, sample flow rate, and size. The research plan is to develop and experimentally demonstrate a new method for generation of air flow in the device, demonstrate sensor operation across a wide range of harsh, real-world operating conditions, and realize a new technique for aerosol sampling and handling that improves the sensor level of detection. The successful outcome of the project would culminate in a low-cost analytical instrument that provides real-time mass concentration of particles in a compact, wearable form factor. The monitor would be suitable for quantification of personal exposure to a range of environmental pollutants such as automotive exhaust, wood smoke, and nanoparticles. Other markets for the instrument include ventilation control, industrial hygiene, power plant monitoring, pharmaceutical powder processing, monitoring in aircraft and automobiles, and consumer air quality monitoring.