In this study, we investigated engineered nanoparticle (ENP) release associated with the contamination of personal protective clothing during the simulated motion of the human wearing the ENP-contaminated protective clothing and evaluated the relative ENP retention on the fabric. The release of airborne ENPs can contribute to inhalation exposure, which is the route of exposure of most concern to cause adverse health effects in the pulmonary system. The evaluation focuses on four popular fabric materials making the laboratory coats (cotton, polypropylene, polyester cotton blend, and Tyvek) and three types of ENPs (Al2O3, carbon black (CB), and carbon nanotube (CNT)). The magnitudes of particle contamination and resuspension were investigated by measuring the number concentration increase of airborne particles in sizes of 10 nm to 10 μm and the weight changes on fabric pieces. Collected aerosol particles and contaminated fabric surfaces were further characterized for understanding particle morphology, elements, agglomeration, and surface contamination status. The particle resuspension from the contaminated lab coat fabric was found to vary by the type of fabric material. Cotton fabric showed the highest level of particle resuspension for all three tested ENPs. Data were evaluated to determine the dominant forces responsible for ENP adhesion on the surface of the fabric. Tyvek fabric was determined as the best fabric for trapping Al2O3 and carbon black ENPs, indicating less resuspension of particles, meaning lower subsequent release, but not durable enough to wear for the long term compared with other fabrics.

Developing low temperature, low cost metal oxide gas sensors remains a critical but elusive goal. Additionally, a better understanding of gas-metal oxide interactions during sensing is required to achieve this goal as well as improving the performance of these devices. Here, the authors describe a paper-based gas sensor (PGS) utilizing SnO2 nanoparticles to detect ethanol, CO, and benzene. Proof-of-concept sensor data indicate that the response was increased and viable operating temperature was lowered (≤50 °C) via plasma surface modification techniques using an Ar/O2 gas mixture at a range of applied rf powers and precursor pressures. Temperature dependent response also demonstrates that sensor selectivity can be tuned with plasma treatment parameters. Ethanol response and recovery behavior at operating temperatures ≤50 °C indicate that sensors demonstrate real-time response at relatively low temperatures. Additionally, although the resistance of the PGS does not fully recover postgas exposure, the signal stability and continued response to ethanol with subsequent exposures indicate that sensors could potentially be used multiple times. Optical emission spectroscopy identified species involved in plasma surface modification processes and x-ray photoelectron spectroscopy elucidated how these changes in surface chemistry correlate to PGS performance. The combination of these techniques provides insight into the driving factors controlling the gas detection process. This approach to produce PGSs shows great promise for the fabrication of flexible, inexpensive devices capable of operating at much lower temperatures than current metal-oxide based sensors.

Although nanoparticles have been incorporated in a range of applications, human exposure through surface contamination remains a concern and is under investigation. This is especially true in the context of industrial and research labs, where workers may become contaminated with nanoparticles. Development of appropriate personal protective equipment requires a deeper understanding of how nanoparticles interact with fabrics. The contamination and resuspension behavior of Al2O3, carbon black (CB), and carbon nanotubes (CNTs) with four common lab coat materials (100% cotton, 80/20 polyester/cotton blend, 100% polypropylene, and Tyvek) is presented in this study. To understand the effects of fabric weave pattern and surface chemistry on nanomaterial–fabric interactions, fabrics were treated with C3F8 or H2O(v) plasma to alter surface wettability while maintaining bulk morphology. Changes in surface chemistry and wettability were measured using X-ray photoelectron spectroscopy and water contact angle goniometry on untreated and plasma-treated materials. Contamination and release of nanomaterials were quantified by monitoring the change in mass after contamination and shaking of the fabrics and using scanning electron microscopy image analysis. Overall, the lowest contamination levels arose from exposure to CNTs. Plasma treatment results in differential contamination, with the H2O(v) plasma-treated fabrics demonstrating the lowest CB contamination, whereas the lowest Al2O3 contamination and resuspension occurs with the C3F8-plasma treated cotton. A complex mechanism for nanoparticle interaction with fabrics involving surface chemistry, morphology, and intermolecular forces is discussed. Notably, different surface treatments resulting in materials repellent to airborne particles could be used in treating fabrics used for making protective clothing or work uniforms to minimize the contamination and spread of unwanted particles.

CO and CO2 plasmas were used to modify SnO2 nanoparticles (NPs) to understand the role of key gas-phase species and to explore a potential route for improving these materials as solid-state gas sensors. Excited state species in both plasmas were monitored using optical emission spectroscopy and the NP were analyzed after plasma exposure with x-ray photoelectron spectroscopy. These studies reveal that in the CO2 plasma, CO2 decomposes to CO and O, leading to etching of the SnO2 lattice. Conversely, in the CO plasma, very little O is formed, leading to the deposition of a carbonaceous film on the SnO2 NP. Sensors fabricated with the CO2 modified SnO2 NP demonstrate a higher response to CO, benzene, and ethanol and improved response and recovery behavior when compared with untreated devices. CO plasma modification, however, had a detrimental effect on the gas sensing performance of this material.