Media dispenser

A media dispenser or a culture media dispenser is a device for repeatedly delivering small fixed volumes (typically between 1 ml and 50 ml) of liquid such as a laboratory growth medium like molten agar or caustic or volatile solvents like toluene into a series of receptacles (Petri dishes, test tubes, Fernbach flasks, etc.).

It is often important that such dispensers operate without biological or chemical contamination, and so must be internally sealed from the environment and designed for easy cleaning and sterilization before use.

At a minimum, a media dispenser consists of some kind of pump connected to a length of discharge tubing or a spout.

However, it is limited in the total amount of medium it can dispense before the source bottle requires a refill, making it convenient for small applications but less so for larger.

These devices are capable of extremely high accuracy and are pulse-free (i.e., the fluid is dispensed in a continuous stream rather than with the pulsations of the peristaltic or inductive pumps) but are limited in volume to the total volume of the attached syringe(s), and, once the emptied, the syringe(s) will require refilling before being used again making them of even more limited use than the bottle top dispensers.

Types of pressure syringe pump can vary depending on the company: Despite their drawbacks, peristaltic pumps have so far been the industry standard for dispensing large volumes of laboratory media: they are capable of dispensing fluid continuously from a reservoir into any number of receptacles, can be used for coarse, thick, or gritty fluids as well as free-flowing thin ones, and unlike many of the other dispenser types, the only contact the pumped fluid has during delivery is with the tubing in which it is being transported: there is never any contact with an internal piston, plunger, or diaphragm, which ensures the highest degrees of sterility and precludes virtually any chemical cross contamination.

A pressure injection cell dispenser is capable of administering only the very smallest amounts of extremely pure non-viscous media, though it does so with the absolutely highest degree of precision.