Material
Polystyrene provides a repeatable polymer composition with a defined density and optical response.
Definition
A material platform—not one universal specification
“PSL sphere,” “polystyrene microsphere” and “polystyrene latex bead” describe a particle material and morphology. They do not, by themselves, define the certificate, concentration, distribution, bottle volume or intended use.
Shape
Spherical morphology reduces one major source of orientation-dependent variation compared with irregular particles.
Distribution
A useful standard depends on the certified mean and distribution—not the word “monodisperse” alone.
Selection error to avoid: treating all PSL products of the same nominal diameter as equivalent.
Properties
Why optical and physical properties matter
Current Applied Physics PSL family pages describe a nominal particle density around 1.05 g/cm³ and a refractive index around 1.59 at 589 nm and 25°C. Those values help explain settling behavior and optical response, but the controlling value remains the current product documentation.
Refractive index
Light-scattering instruments report an optical-equivalent response influenced by particle and medium refractive indices.
Density
Density affects suspension, settling, aerosolization and sample homogeneity.
Surface chemistry
Surfactant and surface condition influence colloidal stability, adsorption and agglomeration.
Use cases
Where PSL spheres are used
| Use | What the particles control | Common failure mode |
|---|---|---|
| Particle-counter size response | Defined reference diameter | Choosing a node outside the instrument’s useful response range |
| Count verification | Defined concentration and sampling behavior | Confusing concentration control with size calibration |
| HEPA/ULPA challenge | Aerosol challenge population | Using calibration-grade material without validating challenge generation |
| Semiconductor deposition | Known PSL population before or on a wafer | Confusing bottle material with a finished wafer standard |
| Optical research | Spherical scattering reference | Ignoring refractive-index and wavelength dependence |
Product truth
Always use the exact family and lot documents
- Confirm the manufacturer’s current product page and revision.
- Review the lot-specific certificate for certified mean, uncertainty and distribution.
- Confirm concentration, fill volume, medium, additives, storage and expiration.
- Verify that the intended application is within the family’s stated purpose.
- Document dilution, dispersion and sampling steps that can alter the delivered population.
Applied Physics technical pathway
Match the standard to the measurement—not the other way around.
Send the instrument, medium, target size, concentration, certificate and packaging requirements to Applied Physics for a technical recommendation.