Polystyrene Petri Dish

Updated: 2026-07-31

Overview

Polystyrene Petri dishes are standard laboratory consumables consisting of a flat cylindrical dish and a slightly larger lid. Manufactured from medical-grade polystyrene, they provide an inert surface for microbial or cell growth. Their disposable nature prevents cross-contamination, making them essential in microbiology labs, clinical diagnostics, and pharmaceutical QC. First introduced in the late 19th century by Julius Richard Petri, modern versions leverage polystyrene's clarity for microscopic observation and consistent thickness for even heating. Most are pre-sterilized using gamma irradiation or ethylene oxide to meet ISO 13485 standards for medical devices.

Physical and Chemical Properties

Polystyrene offers high optical clarity (88-92% light transmission) for colony counting under microscopes. The material has low water absorption (<0.1%) which maintains dimensional stability during incubation. Its surface energy (40-42 dynes/cm) allows proper cell adhesion without pretreatment. While resistant to aqueous solutions and weak acids/bases, polystyrene dissolves in aromatic hydrocarbons and chlorinated solvents. Dishes maintain integrity at typical incubation temperatures (up to 80°C short-term) but may warp during autoclaving (121°C). Special tissue-culture treated versions feature plasma-modified surfaces for improved cell attachment.

Main Applications

In clinical labs, they're used for pathogen isolation and antibiotic sensitivity testing (e.g., Kirby-Bauer discs). Pharmaceutical companies employ them in sterility testing per USP <71>. Food manufacturers conduct surface contamination assays, while environmental labs analyze water/air samples. Cell culture applications include stem cell research and vaccine development, often using treated versions with grid markings. Industrial uses extend to mycology (mushroom cultivation) and educational demonstrations. Ventilated versions with gas-permeable lids support anaerobic cultures when used with gas packs.

Safety and Storage

Pre-sterilized dishes should remain sealed until use to maintain sterility. Opened packages should be used within 2 weeks when stored properly. Never reuse dishes due to potential biofilm formation - proper biohazard disposal is required for contaminated units. Polystyrene dust from broken dishes may irritate respiratory tracts. While non-toxic, additives like mold-release agents could affect sensitive cell lines. Always verify biocompatibility certificates (USP Class VI or ISO 10993) for cell culture applications. Shelf life is typically 3-5 years from manufacture when stored below 30°C.

B2B Procurement Guide

Bulk buyers should specify: diameter (standard 90mm or 100mm), depth (shallow/deep well), stacking rim design (nested or separate), and packaging (individually wrapped or bulk-packed). Tissue culture grades command 20-30% premium over standard grades. For regulated industries, request certificates of analysis showing sterilization validation (typically 25kGy gamma) and endotoxin levels (<0.25 EU/mL). Some suppliers offer customization like double lids or colored rings for sample tracking. MOQs usually start at 1,000 units, with lead times of 2-6 weeks for specialty items.