Improved Swab Design for Contact Sensing

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Project Description

This project seeks to develop new, low-cost, high-performance polymeric traps that will be drop-in replacements for existing materials used in contact sampling for trace explosives detection. Key characteristics of the envisioned traps include:

  1. Conductive, to minimize static electricity effects on sampling handling and to allow electrical fields to be used to modify residue capture and release profiles,
  2. Chemically- and mechanically-stable at temperatures up to 400 °C to withstand the local environment during thermal desorption in future ion mobility spectrometer (IMS) systems, and
  3. Comprised of nano- and microstructured polymeric brushes of varying length and width to allow interrogation of a wide range of features on surfaces of interest in air transportation security environments

The envisioned traps will be fabricated using an electropolymerization mechanism and will be compatible with low-cost, high-efficiency reel-to-reel processing methods. They will be implemented using the same sampling wands as used with existing traps. Due to their chemical and mechanical robustness, they will last much longer than existing traps, offering cost savings due to a reduced need to replace worn traps. In prior work, we have demonstrated that existing trap technology may ‘miss’ as much as 30% of the explosive residue on a surface, depending on the size of the residue, the trap, and the surface under study. This may result in false negative signals during contact sampling, which would jeopardize the health and safety of air travelers. By combining our expertise in explosives characterization and polymer engineering, we can provide a highly engineered solution to this problem that will offer superior performance at comparable cost to existing technology.

A unique aspect of the traps under development here is their ability to conduct charge. This allows the user to apply an electrical bias to the traps, potentially improving their ability to attract residues under certain conditions, and also potentially lowering the temperature required to desorb residues in the IMS. In addition to lowering the temperature for desorption, electrical ramping of the potential on the traps would allow for programmed desorption of target species of interest, opening the door to enhanced resolution in IMS detection and the ability to tolerate ‘dirtier’ sampling environments while still providing effective performance.

Project Leader
  • Stephen P. Beaudoin
    Purdue University

Students Currently Involved in Project
  • Johanna Smith
    Purdue University
  • Melissa Sweat
    Purdue University