Browsing by Author "Mushfiq, Mohammad"
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Item Detecting CO2 Using Nanowire Chemiresistive Sensor for Monitoring Air Quality in Enclosed Space Habitat(44th International Conference on Environmental Systems, 2014-07-13) Alam, Maksudul M.; Mushfiq, Mohammad; Sampathkumaran, Uma; Goswami, Kisholoy; Brosha, Eric L.Monitoring carbon dioxide (CO2) concentration within an enclosed space habitat is critical to ensuring the safety of astronauts and their overall well-being in space because CO2 produced through respiration can accumulate rapidly within closed spaces. If not properly managed, the space crew could experience increased respiratory rate, headaches and hyperventilation, impaired vision and hearing, and decreased cognitive abilities. Currently, non-dispersive infrared (NDIR) spectroscopy is considered the most sensitive system (for a calibrated condition of 21.1 °C and 1 atmosphere) for detecting CO2 during manned space flight. However, measurements are not reliable and error rate increases with variation of temperature, pressure and composition of gas. A more robust and accurate sensor system is required for reliable measurement and monitoring of CO2 under temperature/pressure variations. InnoSense LLC (ISL) explores the development of a polymer nanowire sensor as a potential robust and real-time air-quality monitoring system for accurate, reliable and sensitive detection of CO2 in enclosed spaces. The nanowire sensor is a chemiresistive junction composed of two solid state electrodes bridged by conducting polymer materials in the form of ~70–150 nm diameter wires. The electron transport properties of the sensor change upon exposure to CO2. The nanowire sensors can detect CO2 in the 0–10,000 ppm range with high sensitivity (~50 ppm) and selectivity in the presence of 0–80% relative humidity and temperatures from 0–60 °C. The sensor response time to CO2, across all measured concentration ranges, was 2 minutes. The sensors are capable of detecting CO2 reversibly and self-regenerate to baseline signal within 30 minutes upon CO2 removal.Item Nanomaterials Based Gas Sensor for ISRU Process Contaminants(2024 International Conference on Environmnetal Systems, 2024-07-21) Mushfiq, Mohammad; Zhang, Liyue; Ishihara, Kristi; Paul, Jeffery; Sampathkumaran, Uma; Zhang, Sen; Tang,YifanNASA is seeking sensing technologies for In Situ Resource Utilization (ISRU) process gases. One particular need is monitoring impurities such as hydrogen sulfide (H2S), hydrogen chloride (HCl) and hydrogen fluoride (HF) in the ISRU oxygen stream. Such sensors serve as both safety and process monitoring devices and are critical for the successful operation of ISRU systems. InnoSense, in collaboration with the University of Virginia (UVA), is developing an innovative process gas monitoring (PROMON�) device. PROMON builds on InnoSense�s proprietary single walled carbon nanotube � based sensor platform. It is further enabled by novel intermetallic nanoparticles (NPs) with precise size and composition control, serving as the key sensing element. Additionally, PROMON will include a ruggedized in-line design, providing real-time monitoring under harsh environment without reactant loss from slipstream. A similar sensor using different NPs has been developed by the team for regenerative fuel cell oxygen stream, demonstrating its capability of monitoring H2 in the concentration range of 12.5 � 12500 ppm under both ambient and high pressure (up to 300 PSI), at high temperature (up to 85�C) and high humidity (near condensing). This sets up the basis for PROMON development. In this STTR project, the initial focus is to validate the PROMON proof-of-principle, demonstrating sensor resolution, sensitivity, selectivity and durability, targeting H2S. This includes the development of (1) core sensing materials, (2) sensor units, (3) sensor test platform, and (4) benchtop prototype. In the future, we will expand targets to HCl and HF, optimize the sensor and prototype design, recognition chemistry and algorithm, and perform rigorous characterization. During future moon and mars missions, PROMON will serve as a robust sensor capable of monitoring contaminants in ISRU process gas. With its versatility, PROMON can also be adapted as a general gas detector or monitor for other analytes, toward meeting NASA needs.Item Nanomaterials Based In-Line Sensor for Ionic Silver in Spacecraft Potable Water Systems(2024 International Conference on Environmnetal Systems, 2024-07-21) Ishihara, Kristi; Liu, Yuchu; Mushfiq, Mohammad; Wang, Sijian; Zhang, Xiaowei; Paul, Jeffery; Sampathkumaran, Uma; Zhong, Mingjiang; Tang,YifanNASA is seeking sensing technologies for the in-line measurement of ionic silver (Ag+) as the biocide in spacecraft potable water systems. For human exploration missions, it is critical to monitor Ag+ concentration to maintain a sufficient yet safe level of Ag+ in the water. To address this need, InnoSense and its Small Business Technology Transfer (STTR) partner, Yale University, are developing an innovative nanomaterial-enabled Silver Monitor (SilMon�) building on InnoSense�s proprietary nanomaterials-based sensing platform and customized recognition molecules (RMs) synthesized at Yale. In the progress to date, the team has developed an interdigitated electrode (IDE)-based sensor functionalized with single-walled carbon nanotubes (SWNTs) and unique recognition molecules (RMs) for Ag+ detection. Resistance (R) measurement and scanning electron microscopy are used for IDE characterization and quality control. Currently, device yield is at least 82% for the targeted R values. A SilMon prototype hardware has been developed for systematic sensor evaluation. The prototype contains in-line flow cells for measuring IDEs. Additionally, a flow channel and control hardware were also developed to mimic both flowing and static conditions in the water processor assembly (WPA). The IDEs were evaluated using the SilMon flow cell prototype. Both deionized (DI) water and 200 ppb Ag+ were used as the background and Ag+ solutions of various concentrations served as the analyte. SilMon has demonstrated a wide response ranging from single ppb up to 4000 ppb. More efforts were focused in the targeted 100 � 600 ppb Ag+ concentration range, demonstrating good sensitivity, reversibility and baseline stability. Thorough evaluation of the sensor response, stability, recovery, and cross sensitivity towards interfering species is ongoing. Additionally, an artificial intelligence (AI) based recognition algorithm using deep neural network (DNN) is being developed to further enhance the sensitivity, selectivity and accuracy.