Enclosure helps doctors see surgeries live

Dayton, OH -The use of video conferencing in clinical settings helps medical specialists see procedures live and obtain consultation from experts around the world. And while designing such a system isn't brain surgery, it does present a unique set of challenges.

In designing the MedRover 9000 medical cart, Wayne Lippy, the director of engineering for AAC Inc. (Dayton, OH) and head of a team of engineers who brought the Med Rover 9000 to life, took into consideration the specific requirements imposed by the operating room environment. Operating rooms at hospitals and clinics expose medical equipment to a variety of fluids. The enclosure houses a slide-out keyboard, a VCR, a PC, microphones, a camera, monitor, panel, and other electronic components.

"Water and cleaning solutions are used for cleaning and scrubbing, so the cart had to be watertight," says Lippy. "Washdowns sometimes resemble water coming out of a fire hose."

Key to the MedRover's success is the unit's custom-made enclosure from Rittal Corp. (Springfield, OH). Rittal's major challenge was including existing design features from a PC enclosure, an industrial enclosure, and a data communications enclosure, according to Henry Montero, a senior design engineer with Rittal. "A special roof design matches the contour of the beveled PC door profile," he says.

Foam gasketing prevents fluids that are present in operating rooms from entering the enclosure. It also protects electronic components with a NEMA 12 rating.

Instead of a peel-and-stick gasket material, the enclosure features a form-in-place gasket, which is robotically dispensed onto the enclosure's surface as a liquid, filling "nooks and crannies" as it solidifies. "Peel-and-stick gasketing sometimes loses its stick over time," says Tim McMurdo, Rittal's manager of technical services. The foam gasketing is malleable and forms a tight seal around the enclosure's frame edge. The bond created on the enclosure lasts more than three years, according to McMurdo.

The gasketing is a unique blend of polyether polyol and isocyanate formulated for adhering to the enclosure's baked-on powder coating. The powder coating also protects against fluids that could corrode the enclosure's cold-rolled sheet steel substrate and expose sensitive internal components to fluids. The coating has an ASTM 3363 hardness and an ASTM 3359 adhesion rating.

Electromagnetic Interference (EMI) is a concern in hospitals and clinics, especially in operating rooms where electronic devices operate in close proximity to one another. A storage compartment on the MedRover allows access to medical devices without opening the enclosure door, maintaining a completely conductive path that helps keep stray electromagnetic waves from sneaking in or out of the box. The foam gasketing can protect against low levels of noise when used in conjunction with other enclosure accessories such as contact clips, braided ground straps, and protective cable-entry panels, but the MedRover did not require these accessories.

Lippy had to design for frequencies from 15 Hz to 1 GHz. Although protecting the electronic equipment inside the box was one issue for Lippy, the amount of EMI emitted by the equipment was even more of a concern for him.

Key to preventing the MedRover from interacting with other medical devices is a medical device storage tray on the side of the MedRover. The tray eliminates the need for opening the front enclosure door when retrieving peripheral devices. Holes and openings effect EMI transmissions. The larger the hole, the greater the effect the noise has on components, so keeping the front door closed helps protect other medical devices from interference emitted from the MedRover.

MedRover is currently in use at dozens of hospitals around the world.