SIMS can focus its beam spot down to nanometers, making it the imaging mass spectrometry with the highest spatial resolution; LDPI 2–3 μm is suitable for single-cell/subcellular small molecules; DESI and conventional MALDI are at the tissue scale (tens of micrometers).
The resolution difference stems from the mechanism: SIMS uses a focused ion beam for physical sputtering, LDPI/DESI use a laser spot/droplet, and MALDI uses a laser spot.
Nanometer resolution lets SIMS see organelle-level elemental distributions and material surface/interface diffusion; but its coverage of biological macromolecules and broad-polarity metabolites is limited, and it requires vacuum and conductive samples.
Therefore, 'capable of reaching nanometers' does not mean 'everything is suitable for nanometer resolution'; trade-offs should be made according to the target molecule and sample morphology.
If the goal is single-cell (cells are about 10–20 μm), LDPI 2–3 μm is already sufficient, without needing the nanometer level of SIMS; the step size needs to be less than or equal to the resolution magnitude (see sectioning and step size).
For most biological small-molecule imaging, the single-cell scale is met by LDPI-class sources, while the nanometer level is reserved for SIMS-specific scenarios.
First ask 'how fine do you need to see': elements/nanostructures -> SIMS; single-cell small molecules -> LDPI; tissue metabolism -> DESI/MALDI.
Resolution is also coupled with scan step size and sample preparation; looking at the nominal value alone is insufficient, and small-sample validation is needed.
To obtain detailed specifications, compatible models, or a quotation for the MSI LDPI / DPI full series imaging ion sources, visit the Neo-Source official website, or contact the official team for compatibility advice tailored to your mass spectrometer (Agilent / SCIEX / Thermo and other mainstream MS).