Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors
John G. Gillen, Marcela N. Najarro, Matthew E. Staymates, Scott A. Wight, Marlon L. Walker, Jennifer R. Verkouteren, Eric S. Windsor, Aaron A. Urbas
A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops (typically 50 pL/microdrop) of a concentrated aqueous ammonium nitrate solution from a drop-on-demand (DOD) inkjet printer at specific locations on a silicon substrate rendered hydrophobic by a perfluorodecytrichlorosilane monolayer coating. As a result of the surface treatment, deposited liquid droplets form into the shape of a spherical shaped cap; during the evaporation process, a deposited liquid droplet maintains this geometry until it forms a solid micrometer sized particle. Arrays of solid particles are obtained by sequential translation of the printer stage. The use of DOD inkjet printing for fabrication of discrete particle arrays allows for precise control of particle characteristics (mass, diameter and height) as well as the particle number and spatial distribution on the substrate. The size and shape of individual particles can be controlled by changing the number of microdrops/spot, the contact angle of the substrate, or the concentration of the starting solution. The final mass of an individual particle is precisely determined by using gravimetric measurement of the average mass of solution ejected per microdrop. The primary application of this method is fabrication of test materials for the evaluation of spatially resolved optical and mass spectrometry based sensors used for detecting particle residues of contraband materials such as explosives or narcotics.
, Najarro, M.
, Staymates, M.
, Wight, S.
, Walker, M.
, Verkouteren, J.
, Windsor, E.
and Urbas, A.
Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors, Journal of Sensors, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918133
(Accessed April 19, 2021)