The broader impact/commercial potential of this Small Business Innovation Research (SBIR) project is to develop wearable sensors for monitoring environmental pollution triggers of a chronic respiratory disease, asthma, and empower patients to mitigate exacerbations. The initial target for commercialization is a wearable sensor array, integrated with a smart phone, to detect ozone and nitrogen dioxide, known to cause increased morbidity and mortality in asthma patients. The anticipated product, functionally referred to as Mobile Environmental Exposure Personal Sensor (MEEPS), will use disruptive nanotechnology and signal capture methods to provide superior performance at a lower cost, size, weight and power than competing technologies, such as optical, UV photometry, heated metal oxide semi-conductor (HMOS) and electro-chemical methods. MEEPS will influence proactive healthcare by implementing personalized mitigation approaches tailored to individual symptoms triggered by local exposure, and alerting the caregiver or the physician via mobile phone, as necessary. MEEPS can potentially decrease healthcare costs and financial losses, improve productivity and overall quality of life of asthma patients worldwide. Furthermore, MEEPS enables uploading continuous airborne pollutant exposure data from several users to the cloud for off-line analysis to produce pollution maps, participatory sensing, epidemiological studies, asthma community activism, and increased environmental awareness in STEM disciplines. This SBIR Phase I project proposes to develop low-cost mobile sensor arrays for simultaneous exposure measurements of multiple chemicals in the ambient personal microenvironment. No such device exists in the market today. MEEPS utilizes functionalized carbon nanotubes (CNTs), deposited as thin-films on small flexible electrodes, for the gas-sensitive element. The innovation lies in improving the sensitivity to the target gas while simultaneously reducing the interaction with other oxidizing chemicals present in the environment. This is achieved by controlling the concentration of functional groups covalently attached to the CNTs at the sensor surface. The baseline drift is corrected by differential comparison with the reference signal, periodically monitored prior to gas exposure. MEEPS will integrate CNT detector films with a commercial on-chip low-power impedance measurement circuit, which tracks changes in complex impedance caused by molecular level chemical adsorption of gases on the film surface. In contrast to the well-known chemiresistor, which measures only the change in resistance, MEEPS uses both amplitude and phase to reduce cross-sensitivity to interfering chemicals. The goal of the Phase 1 effort is to mitigate the technical risks of selectivity and sensor drift in ambient microenvironment by utilizing transformational nanotechnology integrated with patent-pending on-board electronics for impedance measurement. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
