Benchtop turbo

The morphology of electrospun nanofibers before and after crosslinking was analysed by Field Emission Scanning Electron Microscopy (FESEM), by using a Carl Zeiss FE-SEM SUPRA 35 VP electron microscope. The images were recorded with an acceleration voltage of 1 keV at approximately 4.5 mm working distance. Electrospun samples were fixed on a conductive carbon tape attached to a metal microscope holder and sputtered with a thin layer of palladium using a Benchtop Turbo sputtering device (Denton Vacuum, USA). The average diameter of cross-linked and non cross-linked nanofibers was measured directly from selected SEM images using ImageJ software and is given as an average value for each sample calculated from at least 20 measurements.

Five-micron-thick serial sections were cut from the formalin fixed, paraffin embedded (FFPE) tissue blocks at the JPC in Silver Spring, MD. A hematoxylin and eosin (H&E) stained slide was prepared and marked by a pathologist (MLS) to identify potential areas of accumulated inhaled PM. The adjacent section was mounted on a highly polished carbon planchet (Ted Pella, Inc. Redding, CA) for FE-SEM/EDS analysis. Carbon planchets were placed on a hot plate and warmed until the paraffin was absorbed by the planchet. Samples were then coated with approximately 20 to 25 nm of carbon in a high vacuum carbon evaporator (Denton, BenchTop Turbo, Moorestown, NJ) to prevent sample charging under the electron beam.

Sub-5 nm Ag film was deposited onto fused silica substrate by thermal evaporator (Denton Benchtop turbo) to compare the quality of ultra-thin printed PPD Ag film with conventionally evaporated PVD one. Ultra-pure silver pellet (99.999% purity, Materion) was used with a deposition rate of 0.4 Å s⁻¹ which is identical to the printed Ag deposition rate with the same thickness. This deposition was carried out without an adhesion layer for a precise comparison to printed Ag film. Metal/dielectric substrate was prepared using a conventional deposition process to demonstrate the feasibility of structural color printing using PPD. Three-nanometer chromium was evaporated as an adhesion layer, then 85 nm Ag film was deposited as a back reflector onto fused silica substrate at 1.7 Å s⁻¹ with the same evaporator. The deposition rate was identical to printed Ag film with the same thickness. SiO₂ dielectric layer was deposited at 0.5 Å s⁻¹ using the radio frequency (RF) sputtering system (Kurt J. Lesker) with various thicknesses to adjust the resonance peak of the cavity.