Airborne particulates (such as vehicle exhaust, dust, and metallics) are a health hazard. Monitors for measuring particulate matter (PM) concentrations in air are typically designed for stationary industrial use; and while they are quite sensitive, they are also bulky, heavy, and expensive. Accordingly, there is a need for PM concentration monitors that are inexpensive and portable so that they can be more pervasive, and also used by mass-market consumers. Recently, various types of portable PM monitors have been developed. One class of monitor uses optical technology to measure particulates flowing through (not deposited on) the device. This optical technology is not sensitive to extremely small particles (with diameters of 200 nanometers or less), yet these small particles are a serious health hazard. Another class of PM monitor uses various technologies to measure the mass of particles deposited on (not flowing through) the device. This type of monitor can be quite sensitive, but eventually, it can become overloaded with deposited particles. Moreover, multiple layers of particles can eliminate the possibility of determining the chemical nature of the particles. To address these shortcomings, researchers at UC Berkeley have developed a means of periodically cleaning deposited particles from mass-sensing components of deposit-based PM sensors. The Berkeley technology results in PM sensors that are not only portable and low-cost, but also have long-lasting functionality.