This paper describes,
in detail, the development of a novel, low-cost,
and flexible drift tube (DT) along with an associated ion mobility
spectrometer system. The DT is constructed from a flexible printed
circuit board (PCB), with a bespoke “dog-leg” track
design, that can be rolled up for ease of assembly. This approach
incorporates a shielding layer, as part of the flexible PCB design,
and represents the minimum dimensional footprint conceivable for a
DT. The low thermal mass of the polyimide substrate and overlapping
electrodes, as afforded by the dog-leg design, allow for efficient
heat management and high field linearity within the tube–achieved
from a single PCB. This is further enhanced by a novel double-glazing
configuration which provides a simple and effective means for gas
management, minimizing thermal variation within the assembly. Herein,
we provide a full experimental characterization of the flexible DT
ion mobility spectrometer (Flex-DT-IMS) with corresponding electrodynamic
(Simion 8.1) and fluid dynamic (SolidWorks) simulations. The Flex-DT-IMS
is shown to have a resolution >80 and a detection limit of low
nanograms
for the analysis of common explosives (RDX, PETN, HMX, and TNT).
Paper spray ionization (PSI) mass spectrometry (MS) is an emerging tool for ambient reaction monitoring via microdroplet reaction acceleration. PSI-MS was used to accelerate and monitor the time course of the reaction of dansyl chloride with aniline, in acetonitrile, to produce dansyl aniline. Three distinct PSI arrangements were explored in this study representing alternative approaches for sample loading and interaction; conventional single tip as well as two novel setups, a dual-tip and a co-axial arrangement were designed so as to limit any on-paper interaction between reagents. The effect on product abundance was investigated using these different paper configurations as it relates to the time course and distance of microdroplet travel. It was observed that product yield increases at a given distance and then decreases thereafter for all PSI configurations. The fluorescent property of the product (dansyl aniline) was used to visually inspect the reaction progress on the paper substrate during the spraying process. Amongst the variety of sample loading methods the novel dual-tip arrangement showed an increased product yield and microdroplet density, whilst avoiding any on-paper interaction between the reagents.
Measurements of streamer lengths in transformer oils under various divergent AC fields and at large gaps (s8cm) have been conducted. Positive streamers play a dominant role in breakdown since their propagation lengths are much larger than negative ones. Several configurations of electrodes have been investigated and some geometrical effects have shown up.
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