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Rationale: Ion trap mass spectrometers are attractive due to their inherent sensitivity and specificity. Miniaturization increases trap portability for in situ mass analysis by relaxing vacuum and voltage requirements but decreases the trapping volume. To overcome signal/resolution loss from miniaturization, double resonance ejection using phase tracking circuitry was investigated. Methods: Phase tracking circuitry was developed to induce double resonance ejection in a planar linear ion trap using the β 2/3 hexapole resonance line. Results: Double resonance was observed using phase tracking circuitry. Resolution of 0.5 m/z units and improved signal‐to‐noise ratio (SNR) compared with AC resonant ejection were achieved. Conclusions: The phase tracking circuitry proved effective despite deviations from a true phase locked condition. Double resonance ejection is a means to increase signal intensity in a miniaturized planar ion trap. [ABSTRACT FROM AUTHOR]

Rationale: Ion trap mass spectrometers are beneficial due to their intrinsic sensitivity and specificity. Therefore, a portable version for in situ analysis of various compounds is very attractive. Miniaturization of ion traps is paramount for the portability of such mass spectrometers. Methods: We developed an optimized design for a planar linear ion trap mass spectrometer, consisting of two trapping plates with photolithographically patterned electrodes. Each plate is constructed using a machined glass substrate and standard microfabrication procedures. The plates are attached to a patterned circuit board via wire bonds then positioned approximately 5 mm apart. Results: Trapped ions are detected by ejecting them through tapered slits, which alleviate charge buildup. Mass analysis can be performed through either boundary or resonant ion ejection. Better than unit mass resolution is demonstrated with resonant ejection. Conclusions: The optimized planar linear ion trap provides good resolution and the potential for further miniaturization. This was accomplished by vigorously testing variables associated with ion trap design including electrical connections, substrate materials, and electrode designs. [ABSTRACT FROM AUTHOR]

RATIONALE We describe the miniaturization of a linear-type ion trap mass spectrometer for possible applications in portable chemical analysis. This work demonstrates the potential and the advantages of using lithographically patterned electrode plates in realizing an ion trap with dimension y0 less than 1 mm. The focus of this work was to demonstrate the viability and flexibility of the patterned electrode approach to trap miniaturization, and also to discover potential obstacles to its use. METHODS Planar, low-capacitance ceramic substrates were patterned with metal electrodes using photolithography. Plates that were originally used in a linear trap with a half-spacing (y0) of 2.19 mm were positioned much closer together such that y0 = 0.95 mm. A capacitive voltage divider provided different radiofrequency (RF) amplitudes to each of 10 electrode elements (5 on each side of the ejection slit), and the capacitor values were adjusted to provide the correct electric field at this closer spacing. The length of the trapping region, 45 mm, is unchanged from the previous device. RESULTS Electron ionization mass spectra of toluene and dichloromethane demonstrate instrument performance, with better than unit mass resolution for the molecular ion and fragment ion peaks of toluene. Compared with the larger plate spacing, the signal is reduced, corresponding to the reduced trapping capacity of the smaller device. However, the mass resolution of the larger device is retained. CONCLUSIONS Lithographically patterned substrates are a viable pathway to fabricating highly miniaturized ion traps for mass spectrometry. These results also demonstrate the possibility of significant reduction of the ion trap volume without physical modification of the electrodes. These experiments show promise for further miniaturization using assemblies of patterned ceramic plates. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We present a linear type radiofrequency ion trap mass spectrometer consisting of metal electrodes that are lithographically patterned onto two opposing planar ceramic substrates. An electric field for ion trapping is formed by applying specific voltage potentials to the electrode pattern. This technique represents a miniaturization approach that is relatively immune to problems with surface roughness, machining complexity, electrode misalignment, and precision of electrode shape. We also present how these traps allow a thorough study of higher order nonlinear effects in the trapping field profile and their effect on mass analyzer performance. This trap has successfully performed mass analysis using both a frequency sweep for resonant ion ejection, and linear voltage amplitude ramp of the trapping field. Better-than-unit mass resolution has been achieved using frequency sweep mass analysis. Mass resolution (m/\Deltam) has been measured at 160 for peaks of m/z values less than 100. [2012-0380] [ABSTRACT FROM PUBLISHER]

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs—x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed.ᅟ [ABSTRACT FROM AUTHOR]

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM).ᅟ [ABSTRACT FROM AUTHOR]

A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power. Under optimized conditions, the limit of detection (LOD) for benzene was 80 ppbv using SPI, better than the LOD using EI (137 ppbv). System performance was demonstrated by distinguishing compounds in different classes from gasoline. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Detection of larger masses becomes increasingly difficult as the geometrical dimensions of a trap become smaller. • Coplanar traps were developed to investigate limits of ion trap miniaturization. • In spite of a microscale radius, a larger mass range than previous report was demonstrated in a microscale planar linear ion trap (μPLIT). Abstract An extended mass range covering m/z 70–240 in a microscale (r 0 = 800 μm) planar linear ion trap (μPLIT) is demonstrated, enabled by optimization of dipole resonance ejection conditions without increasing trapping voltage or frequency compared with prior results. This represents a significant increase in the measureable mass range of coplanar traps and microscale traps in general. Performance was demonstrated using headspace vapor of octafluorotoluene (OFT) as well as mixture of perflurotributylamine (PFTBA) and OFT. Typical mass resolution of approximately 3 Da (FWHM) was observed. [ABSTRACT FROM AUTHOR]

This paper presents a method for characterizing electric field profiles of radio frequency (rf) quadrupole ion trap structures using sensors based on slab coupled optical-fiber sensor (SCOS) technology. The all-dielectric and virtually optical fiber-sized SCOS fits within the compact environment required for ion traps and is able to distinguish electric field orientation and amplitude with minimal perturbation. Measurement of the fields offers insight into the functionality of traps, which may not be obtainable solely by performing simulations. The SCOS accurately mapped the well-known field profiles within a commercially available three-dimensional quadrupole ion trap (Paul trap). The results of this test allowed the SCOS to map the more complicated fields within the coaxial ion trap with a high degree of confidence as to the accuracy of the measurement. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We present the design and results for a new radio-frequency ion trap mass analyzer, the coaxial ion trap, in which both toroidal and quadrupolar trapping regions are created simultaneously. The device is composed of two parallel ceramic plates, the facing surfaces of which are lithographically patterned with concentric metal rings and covered with a thin film of germanium. Experiments demonstrate that ions can be trapped in either region, transferred from the toroidal to the quadrupolar region, and mass-selectively ejected from the quadrupolar region to a detector. Ions trapped in the toroidal region can be transferred to the quadrupole region using an applied ac signal in the radial direction, although it appears that the mechanism of this transfer does not involve resonance with the ion secular frequency, and the process is not mass selective. Ions in the quadrupole trapping region are mass analyzed using dipole resonant ejection. Multiple transfer steps and mass analysis scans are possible on a single population of ions, as from a single ionization/trapping event. The device demonstrates better mass resolving power than the radially ejecting halo ion trap and better sensitivity than the planar quadrupole ion trap. [ABSTRACT FROM AUTHOR]

The halo ion trap (IT) was modified to allow for axial ion ejection through slits machined in the ceramic electrode plates rather than ejecting ions radially to a center hole in the plates. This was done to preserve a more uniform electric field for ion analysis. An in-depth evaluation of the higher-order electric field components in the trap was also performed to improve resolution. The linear, cubic and quintic (5th order) electric field components for each electrode ring inside the IT were calculated using SIMION (SIMION version 8, Scientific Instrument Services, Ringoes, NJ, USA) simulations. The preferred electric fields with higher-order components were implemented experimentally by first calculating the potential on each electrode ring of the halo IT and then soldering appropriate capacitors between rings without changing the original trapping plate design. The performance of the halo IT was evaluated for 1% to 7% cubic electric field ( A/ A) component. A best resolution of 280 ( m/Δ m) for the 51-Da fragment ion of benzene was observed with 5% cubic electric field component. Confirming results were obtained using toluene, dichloromethane, and heptane as test analytes. [ABSTRACT FROM AUTHOR]

Abstract: We report on the effects of varying higher-order multipole components on the performance of a novel radiofrequency quadrupole ion-trap mass analyzer, named the planar Paul trap. The device consists of two parallel ceramic plates, the opposing surfaces of which are lithographically imprinted with 24 concentric metal rings. Using this device, the magnitude and sign of different multipole components, including octopole and dodecapole, can be independently adjusted through altering the voltages applied to each ring. This study presents a systematic investigation of the effects of the octopole and dodecapole field components on the mass resolution and signal intensity of the planar Paul trap. Also, the effect of dipole amplitude and scan speed under both forward and reverse scan modes have been investigated for various combinations of octopole and dodecapole. A trapping field in which the magnitudes of the octopole and dodecapole are, respectively, set to 0% and +8% of the magnitude of the quadrupole yields the highest mass resolution under the conditions studied. A small threshold voltage for dipole resonance ejection is observed for positive octopole, and to a lesser extent for positive dodecapole, but not for negative poles. When both octopole and dodecapole are negative, a reverse scan produces higher resolution, but this effect is not observed when only one of the components is negative. [ABSTRACT FROM AUTHOR]

We report the design and performance of a novel radio-frequency (RF) ion-trap mass analyzer, the planar Paul trap, in which a quadrupolar potential distribution is made between two electrode plates. Each plate consists of a series of concentric, lithographically deposited 100-μm-wide metal rings, overlaid with a thin resistive layer. A different RF amplitude is applied to each ring, such that the trapping field produced is similar to that of the conventional Paul trap. The accuracy and shape of the electric fields in this trap are not limited by electrode geometry nor machining precision, as is the case in traps made with metal electrodes. The use of two microfabrirated plates for ion trap construction presents a lower-cost alternative to conventional ion traps, with additional advantages in electrode alignment, electric field optimization, and ion-trap miniaturization. Experiments demonstrate the effects of ion ejection mode and scan rate on mass resolution for several small organic compounds. The current instrument has a mass range up to ~180 Thomsons (Tb), with better than unit mass resolution over the entire range. [ABSTRACT FROM AUTHOR]

In radiofrequency ion traps, electric fields are produced by applying time-varying potentials between machined metal electrodes. The electrode shape constitutes a boundary condition and defines the field shape. This paper presents a new approach to making ion traps in which the electrodes consist of two ceramic discs, the facing surfaces of which are lithographically imprinted with sets of concentric metal rings and overlaid with a resistive material. A radial potential function can be applied to the resistive material such that the potential between the plates is quadrupolar, and ions are trapped between the plates. The electric field is independent of geometry and can be optimized electronically. The trap can produce any trapping field geometry, including both a toroidal trapping geometry and the traditional Paul-trap field. Dimensionally smaller ion trajectories, as would be produced in a miniaturized ion trap, can be achieved by increasing the potential gradient on the resistive material and operating the trap at higher frequency, rather than by making any physical changes to the trap or the electrodes. Obstacles to miniaturization of ion traps, such as fabrication tolerances, surface smoothness, electrode alignment, limited access for ionization or ion injection, and small trapping volume are addressed using this design. [Copyright &y& Elsevier]

We describe a novel radio frequency ion trap mass analyzer based on toroidal trapping geometry and micro-fabrication technology. The device, called the halo ion trap, consists of two parallel ceramic plates, the facing surfaces of which are imprinted with sets of concentric ring electrodes. Radii of the imprinted rings range from 5 to 12 mm, and the spacing between the plates is 4 mm. Unlike conventional ion traps, in which hyperbolic metal electrodes establish equipotential boundary conditions, electric fields in the halo ion trap are established by applying different radio frequency potentials to each ring. The potential on each ring can be independently optimized to provide the best trapping field. The halo ion trap features an open structure, allowing easy access for in situ ionization. The toroidal geometry provides a large trapping and analyzing volume, increasing the number of ions that can be stored and reducing the effects of space-charge on mass analysis. Preliminary mass spectra show resolution (m/Δm) of 60-75 when the trap is operated at 1.9 MHz and 500 Vp-p. [ABSTRACT FROM AUTHOR]