Improving Sample Collection Of Trace Particles Of Mock Explosive On Nano Coated Sensor

In protection against explosive-based terrorism, development and mass deployment of miniature sensors can play a tremendous role. In trace explosive detection, one of the challenges is bringing explosive vapor samples from the environment to the sensor element. Such collection of a selective and sufficient amount of air sample will enable the device detect the explosive at lower concentration. This can be done by adsorption of the explosive vapor on a substrate. This research implements the idea by developing a nano coated sensor on a lead zirconate titanate (PZT) substrate. The effects of varying the amount of polyethyleneimine in the nano coating solution of the sensor to adsorb trace particles of a mock explosive are studied. A nano coating mixture of ferrofluid, polyethyleneimine and epoxy are coated on the surface of PZT substrate, and exposed to a magnetic field to create a pattern of cones. Then it is exposed to ultraviolet rays for curing during a 24 hours period. Finally, adsorption tests are conducted on the newly created sensor. In the adsorption test, nitrogen gas is used as carrier and 2-nitrotoluene is used as the mock explosive. The carrier gas is routed to the 2-nitrotoluene in a bubbler. Then the vapor mixture of 2-nitrotoluene and nitrogen is routed to the sensor box. Next the sensor is scanned with a Raman spectrometer for spectral identification. This procedure is conducted on different sensors which are made by varying the amount of polyethyleneimine, and tested before and after plasma etching using argon gas. The results shothat increasing the amount of polyethyleneimine by mass yields an increase in the adsorption rate and also leads to the adsorption of a smaller concentration of the mock explosive. In addition, plasma etching of the sensor further improved these results. It enabled adsorption at a less concentration up to 19 ppm. This research shothat the best composition for consistent and reliable adsorption is 80% ferrofluid, 15% polyethyleneimine and 5% epoxy. The trends in this work indicate further research can lead to this sensor concept being able to capture trace explosive particles on a much lower level