Printed circuit board based segmented quadrupole ion guide

Collisional damping quadrupole ion guides have become popular tools in mass spectrometry. In such devices, ions are cooled by collisions with a buffer gas and focused to trajectories near the axis of the ion guide under the influence of a radio frequency (RF) field. This produces a narrow beam of low-energy ions which can be transported with high efficiency. Typically, quadrupole ion guides are constructed of four parallel rods to which RF voltages are applied. To overcome the dampening of the axial velocity component resulting from collisions with neutral gas particles, an additional static axial field is provided by dividing the rods in several segments and applying an electric potential to each segment. However, this method is mechanically complex, requiring a precise alignment of all segments, and several separate connections for the DC und RF voltages to all segments. In this work, we present a simple and low-cost segmented quadrupole ion guide design that is based on standard printed circuit boards (PCB) including both the segmented electrodes as well as the signal distribution network. Furthermore, we present simulations of the ion movement inside this PCB quadrupole and experimentally evaluate the ion transfer. Our measurements show that the segmented PCB quadrupole with planar electrodes reaches similar ion transmissions in comparison with conventional quadrupole ion guides built from segmented circular rods

Regarding the Influence of Additives and Additional Plasma-Induced Chemical Ionization on Adduct Formation in ESI/IMS/MS

Ion mobility spectrometers (IMS) separate ions based on their ion mobility, which depends mainly on collision cross-section, mass, and charge of the ions. However, the performance is often hampered in electrospray ionization (ESI) by the appearance of multiple ion mobility peaks in the spectrum for the same analyte due to clustering and additional sodium adducts. In this work, we investigate the influence of solvents and buffer additives on the detected ion mobility peaks using ESI. Additionally, we investigate the effects of an additional chemical ionization (CI) induced by plasma ionization on the ions formed by electrospray. For this purpose, we coupled our high-resolution IMS with a resolving power of Rp = 100 to a time-of-flight mass spectrometer. Depending on the analyte and the chosen additives, the ionization process can be influenced during the electrospray process. For the herbicide isoproturon, the addition of 5 mM sodium acetate results in the formation of the sodium adduct [M + Na]+, which is reflected in the ion mobility K0 of 1.22 cm2/(V·s). In contrast, the addition of 5 mM ammonium acetate yields the protonated species [M + H]+ and a correspondingly higher K0 of 1.29 cm2/(V·s). In some cases, as with the herbicide pyrimethanil, the addition of sodium acetate can completely suppress ionizations. By carefully choosing the solvent additive for ESI-IMS or additional CI, the formation of different ion mobility peaks can be observed. This can facilitate the assignment of ions to ion mobility peaks using IMS as a compact, stand-alone instrument, e.g., for on-site analysis

Positive Reactant Ion Formation in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS)

In contrast to classical Ion Mobility Spectrometers (IMS) operating at ambient pressure, the High Kinetic Energy Ion Mobility Spectrometer (HiKE-IMS) is operated at reduced pressures of between 10 and 40 mbar and higher reduced electric field strengths of up to 120 Td. Thus, the ion–molecule reactions occurring in the HiKE-IMS can significantly differ from those in classical ambient pressure IMS. In order to predict the ionization pathways of specific analyte molecules, profound knowledge of the reactant ion species generated in HiKE-IMS and their dependence on the ionization conditions is essential. In this work, the formation of positive reactant ions in HiKE-IMS is investigated in detail. On the basis of kinetic and thermodynamic data from the literature, the ion–molecule reactions are kinetically modeled. To verify the model, we present measurements of the reactant ion population and its dependence on the reduced electric field strength, the operating pressure, and the water concentration in the sample gas. All of these parameters significantly affect the reactant ion population formed in HiKE-IMS

A realistic evaluation of indoor robot position tracking systems: The IPIN 2016 competition experience

We report a novel open competition aimed at evaluating accurate robot position tracking in indoor environments. The competition was organized within the IPIN 2016 (Indoor Positioning and Indoor Navigation international Conference). Here, we describe the competition, the competitors and their final results. The challenges of this new competition included: tracking an industrial robot following an unknown path but with a defined ground-truth, and open positioning system to be deployed on-site, with no restrictions apart from those related to safety issues. Our aim here is to provide sufficient detail to serve as a solid basis for future competition initiatives with a similar scope, using common metrics and objective evaluation procedures. In addition, the real systems evaluated represent state-of-the-art performance, and thus offer interesting solutions to the problem posed in the competition.Agencia Estatal de InvestigaciónUniversidad de Alcal

Reliable Long-Range Multi-Link Communication for Unmanned Search and Rescue Aircraft Systems in Beyond Visual Line of Sight Operation

With the increasing availability of unmanned aircraft systems, their usage for search and rescue is close at hand. Especially in the maritime context, aerial support can yield significant benefits. This article proposes and evaluates the concept of combining multiple cellular networks for highly reliable communication with those aircraft systems. The proposed approach is experimentally validated in several unprecedented large-scale experiments in the maritime context. It is found that in this scenario, conventional methods do not suffice for reliable connectivity to the aircraft with significantly varying overall availabilities between 68% and 97%. The underlying work, however, overcomes the limitations of single-link connectivity by providing availability of up to 99.8% in the analyzed scenarios. Therefore, the approach and the experimental data presented in this work yield a solid contribution to search and rescue drones. All results and flight recording data sets are published along with this article to enable future related work and studies, external reproduction, and validation of the underlying results and findings