A Miniature Four-Channel Ion Trap Array Based on Non-silicon MEMS Technology

Abstract

With the increasing application field, a higher requirement is put forward for the mass spectrometer. The reduction in size will inevitably cause a loss of precision; therefore, it is necessary to develop a high-performance miniature mass spectrometer. Based on the researches of rectangular ion trap, the relationship between mass resolution and structural parameters of the ion trap array was analyzed by further simulation. The results indicate that, considering the balance of mass resolution and extraction efficiency, the preferable values for the field radius of exit direction y0 and ion exit slot width s0 are 1.61 mm and 200 μm, respectively. Afterwards, a miniature four-channel ion trap array (MFITA) was fabricated, by using MEMS and laser etching technology, and mass spectrometry experiments were carried out to demonstrate its performance. The mass resolution of butyl diacetate with m/z = 230 can reach 324. In addition, the consistency of four channels is verified within the error tolerance, by analyzing air samples. Our work can prove the correctness of the structural design and the feasibility of MEMS preparation for MFITA, which will bring meaningful guidance for its future development and optimization.

Simulation of a Miniature Linear Ion Trap with Half-Round Rod Electrodes

“…In a similar size, the previously proposed miniature four-channel RIT [ 17 ] ( r x = 1.4 mm, r y = 1.61 mm of a single channel) in our laboratory optimized the proportions of high-order fields and improved the analysis performance compared with the single-channel one, but at the cost of almost quadrupled volume and higher amplitude or frequency of the RF signal. The mass resolution of miniature HreLIT in this work with a tiny size between the single-channel and four-channel RIT was the most outstanding in these three ion traps.…”

“…In this case, a Halo ion trap [ 13 ] with a field radius of only 0.5 mm was fabricated with MEMS technology, but the low resolution was confirmed; Yu et al [ 14 ] reported an RIT with a field radius of 1.5 mm, being built by stereo lithography apparatus (SLA) and offering a slightly higher resolution of 100; Huang and co-worker [ 15 ] optimized a MEMS-based RIT by working on the relationships of ion trapping efficiency with length–width ratio and radio frequency (RF) voltage; Szyszka et al [ 16 ] combined the MEMS with 3D printing technology successfully to fabricate a miniature quadrupole mass analyzer, but this structure has lower resolution and ion capacity compared with ion traps. The miniature RIT array proposed in our laboratory [ 17 ] was prepared by MEMS technology, and the resolution could exceed 700. However, there remains much room for improvement compared with ion traps in conventional size.…”

“…On the other hand, the mass resolution could be improved significantly by optimizing the geometric parameters in a fixed shape of electrodes [ 5 , 18 ]. The excessive high-order fields introduced by the oversimplified planar-shaped electrodes of the RIT are more pronounced at micro size, and in consequence, the resolution would be limited to an unremarkable range even with sufficient optimization [ 17 ]. Meanwhile, the promising HreLIT with a field radius of about 5 mm provides excellent MS capability, and the performance could be further improved after optimization [ 19 , 20 ].…”

The Fabrication of Amino Acid Incorporated Nanoflowers with Intrinsic Peroxidase-like Activity and Its Application for Efficiently Determining Glutathione with TMB Radical Cation as Indicator

“…Although these methods present the ideal sensitivity and selectivity for assaying the level of GSH in human cells or tissues, the application of a fluorometric assay suffers from the difficulties caused by the necessity for the derivatization procedures of the samples before measurement, the fact that the utilization of an electrochemical detector needs an operating electrochemical cell with a higher applied oxidation potential, resulting in its shortened life span, and high-performance liquid chromatography, capillary electrophoresis, mass spectrometry, magnetic resonance spectroscopy and surface-enhanced Raman spectroscopy require the use of the expensive, sophisticated and specialized apparatus as well as the requirement for experienced technicians, which severely confines the applications of these techniques in clinical chemistry [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Conversely, the colorimetric assay has received continuous attention as an attractive alternative strategy because it is a simple, convenient, sensitive and accurate route to accomplish the assessment.…”