Originally Published MPMN September 2009

TECH UPDATE: ELECTRONIC COMPONENTS

Cables and Connectors Strive for Minimalism

Bob Michaels

From the nurse’s station and the OR to the laboratory and the retirement home, cables and connectors are everywhere. They help power drug delivery devices, activate robots, run imaging equipment, and pump fluids. But because cables and connectors are everywhere, users demand models that minimize hookup times, shrink real estate, and reduce management and maintenance requirements.

Planar cables fit that bill, according to Paul Warren, lead design engineer at W. L. Gore & Associates Inc. (Landenberg, PA). Used for managing pneumatic lines, liquid tubes, and electrical signals, they can eliminate the need for traditional cable carriers, particularly in medical lab automation equipment in which the stroke length is less than 20 in.

Planar cables are bundles of tubes and electrical cables consisting of two or three insulated copper conductors in one small round bundle. “Not all manufacturers use the same process for making them,” Warren notes. “Some manufacturers extrude a jacket material such as silicone or polyurethane over the constructions. We make them by laminating the inner construction—whether it be a power cable, a pneumatic line, or fiber optics—between two sheets of Gore-Tex-expanded PTFE.” The advantage of this type of process, according to Warren, is that it has very little influence on the materials inside the cable. It doesn’t deform them or heat them beyond their maximum temperature tolerance. And because the jacket material is lighter and stronger than extruded types of jackets, it provides an organized method for managing the cables without the need for a cable chain. “You can also stack these cables on top of one another because the jacket is very slippery,” Warren adds.

Cable management and reliability is foremost in customers’ minds, Warren emphasizes. “They ask us, ‘how can we get longer life out of our cables? How can we make them easier to install?’” To increase reliability, cables must be properly routed and managed—a time-consuming process for discrete round cables, air lines, and cable chains. In such instances, clamps are required, and the cable chains need dividers. “By contrast, in planar cable construction, cable management is taken care of in a single manufacturing step,” Warren says. “All of the cable components are held in place so that they don’t move, cross over, and cause premature component failure.”

Connecting the Dots

Cables are useless without connectors. And like cable manufacturers, suppliers of connectors are offering designs that minimize setup times while ensuring that connections are as unobtrusive as possible.

A case in point is Souriau USA Inc. (York, PA), whose Push Pull connectors can be connected and locked by a single push motion and disconnected by pulling on a sleeve. “Whereas customers used to pick more-general-purpose connectors in the past, now they’re looking for specific connectors designed for the medical industry,” remarks Riaz Mohammad, Souriau’s business development manager. “With medical electronics, the trend is to pack an increasing number of channels, lines, or wires into as small a form factor as possible.” Thus, the company’s Push Pull connectors range in size from size 00, which accommodates cables approximately 1 mm in diameter, to size 3, which accommodates 12-mm cables. “We have high-density patterns in each of these sizes to accommodate the special needs of the medical industry,” Mohammad adds.

“One connector trend we see in the medical industry is miniaturization,” Mohammad says. “More and more, customers are requesting that our connectors become part of the equipment design, so that they don’t stick out like separate components but look as if they were designed with the specific piece of equipment in mind.”

In addition, OEMs are becoming interested in mixed power and signal designs. While users in the past separated power and signal in different channels and different connectors, today’s systems are integrated and miniaturized. Users are also clamoring for designs that carry power and signal over a composite cable, eliminating the need for additional connectors. “Instead of using two connectors—one for power and one for the signal—composite shielded cables are being used to separate power and signal but through one connector,” Mohammad comments.

In short, for cables and connectors, the word is minimalism.

Copyright ©2009 Medical Product Manufacturing News