Robert Graham Cooks

Miniature Monolithic Rectilinear Ion Trap Arrays by Stereolithography on Printed Circuit Board

This paper reports the creation and characterization of monolithic arrays of miniature rectilinear ion traps (RIT) with common electronic packaging materials. Miniature ion traps benefit from a lower operating voltage as their dimensions decrease. Their integration into circuit board materials facilitates smaller and more integrated sensor systems. Arrays of ion traps provide a larger ion trap storage volume to increase sensitivity lost from size reduction. A new technique, integrating stereolithography-produced ion traps on planar rigid substrates, makes possible the 3-D isolation techniques for more complex monolithic structures. A description of the fabrication process is included. Performance-limiting metrics of the mass analyzer, such as geometrical and electrical deviations, are analyzed to determine their magnitudes for design improvement. The integration of the array with the PCB replaces complex wiring schemes with traces routed within existing multilayer substrates. The substrate can serve as the integration platform for an entire mass spectrometer in a package.

Quadrupole ion traps and trap arrays: geometry, material, scale, performance

Quadrupole ion traps are reviewed, emphasizing recent developments, especially the investigation of new geometries, guided by multiple particle simulations such as the ITSIM program. These geometries include linear ion traps (LITs) and the simplified rectilinear ion trap (RIT). Various methods of fabrication are described, including the use of rapid prototyping apparatus (RPA), in which 3D objects are generated through point-by-point laser polymerization. Fabrication in silicon using multilayer semiconductor fabrication techniques has been used to construct arrays of micro-traps. The performance of instruments containing individual traps as well as arrays of traps of various sizes and geometries is reviewed. Two types of array are differentiated. In the first type, trap arrays constitute fully multiplexed mass spectrometers in which multiple samples are examined using multiple sources, analyzers and detectors, to achieve high throughput analysis. In the second, an array of individual traps acts collectively as a composite trap to increase trapping capacity and performance for a single sample. Much progress has been made in building miniaturized mass spectrometers; a specific example is a 10kg hand-held tandem mass spectrometer based on the RIT mass analyzer. The performance of this instrument in air and water analysis, using membrane sampling, is described.