Wearable Microsystem for Continuous Multi-Vapor Monitoring

Details

• Personal Author:
  Batterman SA ; Kurabayashi K ; Steinecker W ; Zellers ET
• Description:
  This report concerns the successful development and characterization of a wearable prototype instrument that uses a gas chromatographic microanalytical system (uGC) for near-real-time recognition and quantification of the components of moderately complex mixtures of airborne volatile organic compounds (VOC) encountered in working environments. Over the course of the project, we developed new microfabricated (Si-glass) components for preconcentration/injection, separation, and detection, and we assembled and characterized the performance of two prototype uGC-based instruments, referred to as Personal Exposure Monitoring Microsystems (PEMM). The first prototype, PEMM 1, is a compact benchtop instrument that operates on AC power and is controlled by a laptop computer through a graphical user interface. The second prototype, PEMM 2, is a belt-mountable, battery powered instrument run by an embedded microcontroller. PEMM 1 is the progenitor of PEMM 2 and both instruments can operate autonomously. Innovative designs and strategies were implemented to create the component devices and configurations used in both prototypes. For both PEMM 1 and PEMM 2, a simple wall-coated capillary pre-trap is used to selectively retain intractable (low-volatility) interferences, and then purge them at room temperature between sequential measurements. VOCs above a threshold vapor pressure (pv) of approximately 0.03 kPa pass into the partially selective, dual-adsorbent micro-preconcentrator/focuser (uPCF). Those vapors with pv values from 0.03 to approximately 13 kPa are quantitatively trapped, focused, and injected into the downstream microcolumn(s). For PEMM 1, a pair of series-coupled ucolumn chips with integrated heaters and temperature sensors and stationary phase of cross-linked polydimethylsiloxane (PDMS) is used for temperature-programmed chromatographic separations. For the PEMM 2, a single ucolumn chip with three independently heated zones is used to afford more power-efficient, high-resolution, high-speed separations of VOC mixture components. For both prototypes, detection is achieved with an array of 4-5 microsensors comprising chemiresistors with monolayer protected nanoparticle interface layers. By using differently functionalized monolayers on the nanoparticles, each eluting VOC generates a set of responses from the array that differ from the set of responses for other VOCs. Detection limits in the sub-ppm range are achieved for all vapors from collected air samples of 5-10 mL. By combining retention times and response patterns, it is possible to differentiate and recognize all of the VOCs in a mixture. The uGC components of the PEMM 2 are combined with a commercial mini-pump, a small on-board He gas supply, mini-valves, interface circuitry, an embedded microcontroller for operating the instrument, and a mediated wireless link for and storing exposure data and post-shift downloading of data to a remote host computer. Subsequent chemometric analysis of the chromatographically resolved array response patterns for each mixture component permits construction of time-exposure profiles for comparison with occupational exposure limits or classification of exposure frequencies and intensities for epidemiologic studies. The PEMM 2 is powered by a separate battery pack and is small/light-weight enough to mount on the belt of a worker. It is capable of simultaneous personal exposure measurements of at least 21 specific, user-selectable VOCs every 6-10 minutes. The capability for assessing worker exposures to VOCs was demonstrated through a series of mock-field tests. No such instrument existed prior to this study. [Description provided by NIOSH]
• Subjects:
  Occupational Health Safety Solvents Volatile Organic Compounds Volatilization
• Keywords:
  Equipment Design Gas Chromatography Monitors Vapor Detectors Vapors VOCs Volatile Organic Compounds Wearable Technologies
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Michigan ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-102
• NIOSHTIC Number:
  nn:20055715
• NTIS Accession Number:
  PB2019-100850
• Citation:
  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, R01-OH-010297, 2018 Jul; :1-102
• Contact Point Address:
  Edward T. Zellers, PhD, Professor, Department of Environmental Health Sciences, 1415 Washington Heights, University of Michigan, Ann Arbor, MI
• Email:
  ezellers@umich.edu
• Federal Fiscal Year:
  2018
• Performing Organization:
  University of Michigan, Ann Arbor
• Peer Reviewed:
  False
• Start Date:
  20130901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20170831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:c75040aff3273bac77cbe1bd425c50135d83dca18a90a486d11fb050511dd167874d34b8304a8b58286d275de93d78577a47b629a4788732db8cf8e704292b7e
• Download URL:
  https://stacks.cdc.gov/view/cdc/218864/cdc_218864_DS1.pdf
• File Type:
  [PDF - 5.74 MB ]