Novel hydrogen sulfide sensors for portable monitors.
Hooker-M; Benstock-EJ; Deininger-DJ; Hooker-SA; Kostelecky-CJ; Williams-SS; Womer-K
Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R43-OH-007471, NIOSH 2002 Jul; :1-31
During this SBIR Phase I project, Nanomaterials Research (NRLLC) successfully demonstrated a new type of sensor device for detecting hydrogen sulfide (H2S). This gas is extremely toxic at low concentrations, and workplace exposure is common in a number of industries. Improved sensors and gas detection instruments are sorely needed to ensure protection of these exposed workers and to reduce H2S emissions into the atmosphere, thereby affecting public health. NRLLC's new sensor device combines recent advances in both semiconductor materials and alternative sensor fabrication approaches. These novel components were produced using processes and architectures that are similar to those used in the manufacture of multilayer ceramic capacitors. The sensors had a footprint of only 0.45 cm x 0.30 cm and exhibited the requisite mechanical strength needed for handling and integration into traditional electronic packages. The sensors responded well to H2S at concentrations ranging from 5 to 50 ppm. These levels are commensurate with the monitoring requirements for workplace exposures, in which the personal exposure limit, or PEL, is 10 ppm and the short-term exposure limit, or STEL, is 15 ppm. The sensors exhibited a large decrease in resistance when the toxic gas was present, which is characteristic of n-type semiconductor behavior. This response was found to be linear with concentration and repeatable during multiple exposures. Response times (t50) were on the order of 20 seconds. Several variables were investigated to determine their effect on the sensor response and recovery. These included the composition of the sensor material, the operating temperature of the device, the particle size of the raw materials, the design of the multilayer structure, and the degree of porosity retained in the final device. While a more extensive study is required, the Phase I results suggest that the processing and operation of the devices can be optimized by controlling such variables, thereby ensuring reliable gas detection. In addition, such devices can be designed to meet specific instrumentation requirements.' The small size and tailorability of NRLLC's sensor devices are important features for implementation of the sensors in gas detection instruments. NRLLC envisions a number of different application scenarios for these sensors including their use in stationary industrial monitoring systems, hand-held detection equipment, and revolutionary new personal monitors based on smart card technology. During the Phase II program, NRLLC plans to explore all three application areas, while building on the Phase I results to optimize sensor performance. This report summarizes the results of our Phase I SBIR project and discusses the potential market opportunities for these unique devices. Details regarding the investigations performed and the primary results obtained are included. In addition, specifics regarding three primary markets for the technology are provided. Additional market information will be included in the Phase II proposal.
Education; Educational-resource-centers; Industrial-education; Occupational-medicine; Occupational-safety-programs; Industrial-health-programs; Industrial-hygiene; Industrial-hygiene-programs; Occupational-medicine; Nanotechnology
Nanomaterials Research, 2021 Miller Drive, Longmont, CO 80501
Final Grant Report
NTIS Accession No.
Research Tools and Approaches; Exposure Assessment Methods
National Institute for Occupational Safety and Health
Nanomaterials Research Corporation, Longmont, Colorado