Simulation Driven Design and Development of Structures for Lossless Ion Manipulations Sandilya V.B. Garimella, Yehia M. Ibrahim, Ian K. Webb, Aleksey V. Tolmachev, Gordon A. Anderson and Richard D. Smith

• Initial designs have 0.75 mm central electrodes withadjacent electrodes of opposite polarity superimposedwith a DC gradient.

• Central electrodes are flanked by guard electrodes thatprovide confinement in XY plane using a DC bias

• Two planes of parallel electrodes are assembled togetherfor trapping and manipulating ions.

• Simulation methods have been applied to these geometries to elucidate the device performance in terms of potentials and ion trajectories

• “Pan-omics” MS-based measurementsbenefit greatly from IMS separations.

• IMS resolving power is limited by appliedelectric field and length of drift region.

• FAIMS, DMS, TW, Cyclotron devices areexamples of systems that attempt at gasphase ion processing to improve or altermobility resolving power.1,2,3

• However, previously developed deviceshave been incurred significant ion losses

• Ion manipulation devices that can provideplatform for lossless, extended, complexgas phase ion manipulation are veryattractive (SLIM devices).

• Theoretical/Computational evaluation ofthe devices is presented.

Introduction

Overview Methods Results

AcknowledgementsPortions of this work was supported by NIHNational Institute of General Medical Sciences (P41 GM103493) and under the LDRD Program atthe Pacific Northwest National Laboratory. Workwas performed in the Environmental MolecularSciences Laboratory, a DOE OBER nationalscientific user facility on the PNNL campus. PNNLis a multiprogram national laboratory operated byBattelle for the DOE under contract DE-AC05-76RL01830.

Conclusions1. Pseudo-Potential Well and Effects of Voltage and Geometry

CONTACT: Sandilya V.B. Garimella, Ph.D.Biological Sciences DivisionPacific Northwest National LaboratoryE-mail: sandilya.garimella@pnnl.gov

www.omics.pnl.gov

Career Opportunities: For potential openings in the Omics Separations and Mass Spectrometry Department at PNNL please contact: Dick Smith at rds@pnnl.govJosh Adkins at Joshua.Adkins@pnnl.gov

𝜑𝜑 = 𝑞𝑞

4𝑚𝑚|∇∅𝑅𝑅𝑅𝑅|2

𝜔𝜔2 + ∅𝐷𝐷𝐷𝐷

Potential Well Depth Calculations

Ion Trajectory Simulations

Δφ= 0

0

100

50

150

0

2. Lossless Ion Transport and Mobility Separations Using SLIM Devices

R-2 = -2 + -2

• Using printed circuit board technologyplanar devices for efficient ion trappingand drift have been constructed

• Straight, Tee, Elbow form the basic unitswhich can be assembled to make devicesfor complex ion manipulation.

• Systematic studies of potentials and ionmotion characteristics in these devices areessential for proof-of-concept, design,development and implementation.

• Solving the pseudo-potential well depth.

• Finite Difference Methodfor numerical solution.

• Matlab implementation.

• CAD designs wereimported into SIMION8.1.

• SDS collisions model forion-neutral interaction.

• SIMION user codes forapplying RF and DCpotentials.

• Ion modeling/simulations have guided initialSLIM design, and subsequent refinements

• Close agreement of simulations withexperiment give confidence in models forsimulation-driven design

• Geometries and voltages can be usedappropriately for manipulating ions inspecific regions to expand applications tomore complex manipulations

References

; RF 0.72 MHz 200 Vp-p10 mm rung electrode width ; guard bias 10 Volts

0 30 60

03060

-10 -5 0 5 10

mm

-2.50.02.5

mm

(a) Ion trajectories calculated by SIMION in a single straight SLIM unit. (b) Simulated and theoretical mean arrival time (m/z1222) through a single SLIM unit. (c) Calculated, theoretical and experimental resolving power through 6 SLIM units (63.2cmlong)

Volts

Volts

Rung Electrode

Guard Electrode

Z

YX

Z

X

UDC + U UDC + UVRF + UDC

central electrode

guard electrode

guard electrode

X

Y

Z

Y

UDC- (n-1)dU + (-1)n VRF

1 2 3 n

central electrodes

guard electrodes bias (U) = 5 V

1 2 3 4 5

6

7

8

9

10

1 2 3 4 5

9

10

8

7

Voltage optimization is essential to execute a90o turn. Simulation directed characterization ofperformance of turns achieved 100%transmission in simulations, which wasreplicated in experiments. Simulations wereused to refine designs.

V7 = V5 – 3* 𝒅𝒅𝒅𝒅𝒅𝒅𝒅𝒅 guard

V6 = V5 – 1* 𝒅𝒅𝒅𝒅𝒅𝒅𝒅𝒅 guard

Transmission = 100%

V7 = V5 – 1* 𝒅𝒅𝒅𝒅𝒅𝒅𝒅𝒅 guard

V6 = V5 – 0.5* 𝒅𝒅𝒅𝒅𝒅𝒅𝒅𝒅 guard

Transmission = 48%

3. Lossless and Complex Manipulations of Ions in SLIM Devices

(c)(b)(a)

Z

YZ

X

(c)(b)(a)

5 mm central electrode, 5mm board gap0.72 MHz , 200 Vp-p RF , 5 V guard bias

(a) Pseudo-potential well in the XZ and XY planes. (b) Trapping well profiles at different guard bias voltages. (c) Pseudo-potentialwell at different rung electrode widths

Simulations show a selected ion mobility (m/z1522) was dynamically switched into anorthogonal SLIM channel The same polarityelectrodes in the Tee inter-section contributedto loss of pseudo-potential and thereby loss ofions to electrodes. ~8% loss of resolvingpower is seen against comparable straightsection due to race track effect. These losseswas recovered through design iterations.

1. Analytical Chemistry, 85(1), 10-132. Analytical Chemistry, 80(24), 9689-96993. Analytical Chemistry, 81(4), 1482-14874. Rapid Comm., 13(5), 422-431