We propose to develop a portable, rugged, handheld multi-gas sensor that is well within the solicitation requirements. We will leverage a mature class of mass sensors that include, for example: quartz crystal microbalances (QCMs) and capacitive micromachined ultrasonic transducers (CMUTs). These sensors boast extraordinary sensitivity to changes in mass (e.g., 50 femtograms for CMUTs) and are used today in several applications including high resolution ultrasonic imaging and film thickness monitoring. The membranes will be coated with materials that exhibit highly selective uptake of the target gases specified in the solicitation. When the device is exposed to a gas molecule that binds to the coating material the resulting mass change will be detected by the mass sensor. The chemical kinetics of the coatings will be engineered to selectively adsorb and desorb the target gases with sub- 10 second response times. We will integrate a commercial particle counter with multiple mass sensors to measure all 12 gases specified in the solicitation. The mass sensors are small and thin (less than 10x10x1 mm) and light (less than 1 gram) and their readout electronics can fit on a standard pc board that is 3 in x 3 in x 0.2 in while consuming 300 mW of power allowing for 17 hours of continuous operation. Because of the extraordinarily small size of our sensor technology, we will be able to use ruggedized packaging to meet the drop test requirement, while still satisfying the target specifications for size, weight, battery life, cost, and response time.
