Study on simulation and experiment of array micro Faraday cup ion detector for FAIMS

Abstract

An array micro Faraday cup ion detector for FAIMS (High-field Asymmetric Waveform Ion Mobility Spectrometry) was introduced, with which the size of the FAIMS system was reduced. With simple structure, good stability, low noise, large measurements range, this detector can work under the condition of atmospheric pressure. The array micro Faraday cup was composed of gate electrode, sensitive electrode and shielding electrode. The sensitive electrode was made of tens of crossing silicon columns with diameter of 200 μm. It was fabricated through typical MEMS technology, which was compatible completely with plane FAIMS. It was shown from FLUENT simulation result that the resistance to gas motion was low and the flow field distribution was helpful for full absorption of the ion in this array design. Through electricity simulation, the method to reduce interference on the detection signal of the micro Faraday cup was given out. Connecting with KEITHLEY 237 ampere meter, the noise level of the array micro Faraday cup was lower than 0.5 pA. The output signal of the acetone sample measured by experiment was about 210 pA. Through contrast experiment, the design parameter of the micro Faraday cup was obtained primarily. This array micro Faraday cup can meet the requirements of the FAIMS system. FAIMS, MEMS, Faraday cup, ion detector, low current Citation:Tang F, Wang X H, Zhang L, et al. Study on simulation and experiment of array micro Faraday cup ion detector for FAIMS.

Ion Mobility-Mass Spectrometry: Time-Dispersive Instrumentation

“… 192 Spatial multiplexing has been demonstrated for spatially dispersive ion mobility techniques such as DMA 193 and FAIMS. 194 In the authors’ laboratory, a spatially multiplexed DTIMS based on eight discrete analysis channels is under development in order to improve several analytical figures-of-merit for temporally dispersed ion mobility, including throughput and sensitivity. 195 This 8-channel prototype incorporates a uniform field drift tube array bracketed by electrodynamic ion funnels, and the ion optics share common electronic connections within a single vacuum system, as depicted in Figure 7 .…”

“…This is the conventional mode of operation for a magnetic sector mass spectrometer utilizing an array detector . Spatial multiplexing has been demonstrated for spatially dispersive ion mobility techniques such as DMA and FAIMS . In the authors’ laboratory, a spatially multiplexed DTIMS based on eight discrete analysis channels is under development in order to improve several analytical figures-of-merit for temporally dispersed ion mobility, including throughput and sensitivity .…”

Acetone Sensor Based on FAIMS-MEMS

“…In short, FAIMS-MEMS sensors achieve rapid identification of gases on site and in situ detection. They are simple and miniaturized equipment, and are convenient and portable [25][26][27][28].…”

Development and first experimental tests of Faraday cup array

“…1-9 Different designs enable various measurement techniques: ion collectors for ion guns; 2 micro-scale Faraday cups in electron microscopy; 3 Faraday cups reducing secondary electron emission in plasma focus experiments; 4 Faraday cups with fast time response for measuring electron beams of traveling wave tube guns. 5 Generally speaking, Faraday cups are used for various types of experimental measurements: ion mass spectrometry; 6 beam current measurement of an ion source where electromagnetic noise is associated; 7 alpha particle detection in tokamaks; 8 ion detection from laser-plasma based experiments.…”