History of the Petri Dish

   Julius Richard Petri (1852-1921), a German bacteriologist, invented the first Petri dish. He used this shallow, circular glass dish with a loose-fitting cover to culture bacteria and other microorganisms. Then, during the mid-1960’s, the injection moulding technology developed sufficiently so that Petri dishes could be manufactured from clear polystyrene plastic. These dishes were merely clones of the first glass Petri dish. They were large, heavy and were almost twice the weight of most conventional plastic Petri dishes manufactured today.

The first plastic dishes were inexpensive, as crude oil and its by-products were cheap commodities. However, in 1973 the Organization of Petroleum Exporting Countries (OPEC) took advantage of shifting market conditions and the geopolitical and economic disruptions in the Middle East, causing the price of petroleum-based products to skyrocket.

As the supply of polystyrene became restricted, the price started to soar; as a result, the cost of plastic Petri dishes also escalated. Customer pressure then forced Petri dish manufacturers to cut back on the excess size and weight of the dishes in an effort to reduce cost. The 25-gram “dinosaur” Petri dishes became extinct.

In the mid-1980’s, further development in raw material and a better understanding of the injection moulding process, allowed most manufacturers to reduce the weight of their Petri dishes to the 15 to 17 grams range. These dishes remained unchanged and became an industry standard for many years without any advances or innovations. Since that time, every company merely copied other companies until the early 1990’s, when Phoenix Biomedical developed, perfected and patented the “STAR™DISH” concept.

Phoenix Biomedical Products, first established as a Canadian company but now operates in Murcia, Spain, has manufactured polystyrene Petri dishes used for diagnostic testing in medical, industrial and research laboratories since 1980.

In its attempts to find a solution to the increasing cost of plastic and the environmental concern with regards to the disposal of medical waste, Phoenix Biomedical’s team of engineers and researchers had developed a new generation of Petri dishes. The “STAR™DISH” is manufactured with up to 35% less plastic, thus helping to preserve our valuable, non-renewable resources and significantly reducing medical laboratory waste.

The “STAR™DISH” series not only reduces the amount of plastic required to manufacture the product, but is also of higher quality, ensuring consistent test results.

The innovative design of the “STAR™DISH” incorporates transparent ribs moulded into the dish. These ribs reinforce the dishes, resulting in stronger, flexible and less brittle dishes than the conventionally designed variety. The ribs also act as a stiffener to keep the bottom from warping, creating a perfectly flat dish.

A method known as “centre-gating” is used in manufacturing the “STAR™DISH”. In this process, the plastic enters the mould cavities from the centre of the dish, runs rapidly through the “ribs” that act as flow leaders, and then flows in a cobweb pattern, thus substantially reducing plastic stress during the filling of the cavity. This unique patented design, in combination with the centre-gating, makes a resilient, flatter Petri dish and allows a reduction in the dish weight without sacrificing quality.

The “STAR™DISH” makes an important contribution in support of strategies to reduce medical plastic waste that is burdening our global environment.

Given the current global size of the Petri dish market, this product can help control costs and significantly reduce the amount of plastic entering our waste system.