Petri Dish Fixation Unit (PDFU)
The Petri Dish Fixation Unit (PDFU) is a complement set of hardware consisting of a specialized holder for a standard 60-mm petri dish, which delivers fixative to the sample in the petri dish and interfaces with the Biological Research In Canisters-Light Emitting Diode (BRIC-LED) hardware. Six (6) PDFUs are contained within each BRIC-LED. The physical dimensions are 6.8 inches (length) x 3.5 inches (width) x 3.75 inches (height). Total weight is 4 lb. Electrical requirements are 6 watts.
The major components of each PDFU include the following items:
chamber for the 60 mm petri dish; chamber for fixative storage; piston for forcing the fixative into the specimen chamber; light rod to channel the illumination provided by the red LEDs; Dual-stage PDFUs are also available, allowing delivery of two fluids to the specimen chamber.
Each PDFU provides two levels of containment to the fixative, which is loaded into the fixative chamber.
Each PDFU consists of a body of polycarbonate which is milled to house the above mentioned chambers. The specimen chamber houses the bottom half of a standard off-the-shelf 60 mm petri dish. The top half of the 60 mm dish is not needed to house the specimen since the top of the assembly (e.g. the PDFU cover and manifold) acts as a cover. A set of three O-rings provides a seal between the PDFU cover and the polycarbonate body. The fixative chamber and the specimen chamber are separated by a check valve to prevent unwanted/early fixation of the specimens.
An additional feature of the PDFU is a light rod which directs the light from each red LED on the BRIC-LED canister's circuit board into the PDFU specimen chamber. This glass light rod is constructed of Pyrex and is sealed into the dish using epoxy.
The inside of the PDFUs have sufficient storage for a passive temperature recorder (substituted for a specimen), or data logger. A PDFU which contains a data logger does not contain any fixative.