Ultrathin Silica Integration for Enhancing Reliability of Microfluidic Photoionization Detectors

Details

• Personal Author:
  Fan X ; Huang X ; Sharma R ; Sivakumar AD ; Yang S
• Description:
  Microfluidic photoionization detectors (µPIDs) based on silicon chips can rapidly and sensitively detect volatile compounds. However, the applications of µPID are limited by the manual assembly process using glue, which may outgas and clog the fluidic channel, and by the short lifetime of the vacuum ultraviolet (VUV) lamps (especially, argon lamps). Here, we developed a gold-gold cold welding-based microfabrication process to integrate ultrathin (10 nm) silica into µPID. The silica coating enables direct bonding of the VUV window to silicon under amicable conditions and works as a moisture and plasma exposure barrier for VUV windows that are susceptible to hygroscopicity and solarization. Detailed characterization of the silica coating was conducted, showing that the 10 nm silica coating allows 40-80% VUV transmission from 8.5 to 11.5 eV. It is further shown that the silica-protected µPID maintained 90% of its original sensitivity after 2200 h of exposure to ambient (dew point = 8.0 +/- 1.8 degrees C), compared to 39% without silica. Furthermore, argon plasma inside an argon VUV lamp was identified as the dominant degradation source for the LiF window with color centers formation in UV-vis and VUV transmission spectra. Ultrathin silica was then also demonstrated effective in protecting the LiF from argon plasma exposure. Lastly, thermal annealing was found to bleach the color centers and restore VUV transmission of degraded LiF windows effectively, which will lead to future development of a new type of VUV lamp and the corresponding µPID (and PID in general) that can be mass produced with a high yield, a longer lifetime, and better regenerability. [Description provided by NIOSH]
• Subjects:
  Chemistry, Analytic Laboratories Occupational Health Safety
• Keywords:
  Algorithms Analytical Chemistry Analytical Instruments Gas Detectors Laboratory Equipment Microchemistry Volatiles
• ISSN:
  0003-2700
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Michigan ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  95
• Issue:
  22
• NIOSHTIC Number:
  nn:20069615
• Citation:
  Anal Chem 2023 Jun; 95(22):8496-8504
• Contact Point Address:
  Xudong Fan, Department of Biomedical Engineering, Center for Wireless Integrated MicroSensing and Systems (WIMS2), and Max Harry Weil Institute for Critical Care Research and Innovation, University of Michigan, Ann Arbor, Michigan 48109, United States
• Email:
  xsfan@umich.edu
• Federal Fiscal Year:
  2023
• Performing Organization:
  University of Michigan at Ann Arbor
• Peer Reviewed:
  True
• Start Date:
  20180901
• Source Full Name:
  Analytical Chemistry
• End Date:
  20220831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a298758e8452b2830ec91498a5dfe2d23a64305b7bc120993ea5a0a6c9e6523503a28318248d4c839cd3e4a97e1d294f01423e54a92e2f197ebc9ebb975bce20
• Download URL:
  https://stacks.cdc.gov/view/cdc/208010/cdc_208010_DS1.pdf
• File Type:
  [PDF - 6.21 MB ]