Aqueous dispersion
Use when the downstream system is water-compatible and a prepared colloidal format reduces the dry-dispersion burden.
Selection sequence
Choose in the right order.
- Define the job. Calibration, verification, optical response, wafer deposition, formulation, filtration, surface modification or research.
- Define the measurand. Projected diameter, hydrodynamic diameter, mobility diameter, optical response, number concentration or another controlled quantity.
- Set the size and distribution requirement. Nominal value alone is insufficient when width, CV or multimodality changes performance.
- Select material and surface. Native amorphous silica, hydrophobic treatment, amine functionalization, polymer coating or another chemistry.
- Select delivery format. Aqueous dispersion, ethanol dispersion or dry powder, with concentration and package volume.
- Define evidence. Certificate scope, traceability statement, uncertainty, morphology evidence, concentration, lot data and safety documentation.
Requirement matrix
What to specify by use case
| Use case | Critical inputs | Common failure |
|---|---|---|
| Particle-size calibration | Instrument model, medium, size method, accepted standard, uncertainty | Buying by nominal diameter without matching the calibration method |
| Optical response | Wavelength, refractive indices, geometry, concentration, path length | Assuming response transfers across instruments or wavelengths |
| Wafer inspection | Tool model, wafer diameter, particle material, deposition pattern, count and size | Treating loose particles and a finished wafer artifact as interchangeable |
| Coating or composite | Matrix, loading, surface chemistry, mixing energy, viscosity, curing | Ignoring agglomeration and interface chemistry |
| Biomedical research | Research objective, purity, functionalization, sterility/endotoxin requirements | Assuming a general research particle is clinical or diagnostic grade |
Fast pathway
Start from the delivery format.
Ethanol dispersion
Use only when solvent compatibility, evaporation behavior and stabilization fit the process. Confirm exact composition and safety controls.
Dry powder
Use when the buyer needs carrier-free material or custom formulation control and can manage dust, wetting and dispersion validation.
Commercial families
Map the requirement to a current Applied Physics pathway.
| Requirement pattern | Initial family to evaluate | Do not assume |
|---|---|---|
| 20–200 nm prepared dispersion | 20–200 nm silica family | Every intermediate size, medium or concentration is standard |
| 250–1000 nm prepared microsphere dispersion | 250–1000 nm silica family | The family label establishes a single measurement method |
| Dry 20–200 nm material | 20–200 nm dry powder | Primary particles will redisperse individually without process development |
| Broader dry silica size range | 100 nm–2.5 µm dry silica | Every size has the same tolerance or packaging |
| Modified surface | Functionalized silica pathways | The functional group alone defines compatibility |
| Finished wafer artifact | Wafer standards | Loose particles and deposited standards are equivalent products |
Questions engineers ask
Frequently asked questions
What is the first field to define when selecting silica particles?
Define the application and measurand first. Target size is important, but the correct material depends on what the particles must help measure, demonstrate or modify.
Should I request a custom size immediately?
Not necessarily. First check whether a standard nominal size meets the instrument, process or research requirement. Custom work adds feasibility, tolerance, minimum quantity and lead-time questions.
Can one silica particle product serve both liquid calibration and wafer deposition?
Not automatically. Delivery medium, concentration, cleanliness, surface chemistry and deposition process may be different even when nominal diameter is similar.
Sources and verification
Technical basis
- NIST measurement protocols — Supports defining the measurand and method before comparing particle-size values.
- Applied Physics silica families — Current commercial sub-200 nm pathway.
- NIOSH nanomaterial guidance — Supports handling controls for engineered nanoscale materials.
Commercial specifications should be confirmed against the current Applied Physics quotation, certificate, lot documentation and product page before purchase or protocol use.
Continue the research
Related technical guidance
Interactive selector
Translate the requirement into a family-level pathway.
Technical brief builder
Prepare a quotable requirement for Applied Physics.
Product families
Compare commercial forms, ranges and use cases.
Applied Physics technical pathway
Need a particle specification reviewed?
Send the target size, medium, concentration, application, certificate requirements and shipping destination. Applied Physics can evaluate the appropriate silica family or custom pathway.