Originally Published MPMN January/February 2002

PROFILE

Miniature Electroformed Housings Help Camera Probes Get Big Picture

Tight-tolerance casings allow smaller size and improved focus

The use of camera probes has increased greatly over the past decade with the rise of minimally invasive surgery and other advanced procedures. Packed with sensors and fiber-optic light bundles, these instruments allow the real-time imaging of otherwise-inaccessible surfaces and cavities. As with most medical products, however, there has been market demand for further miniaturization, which can create new challenges for manufacturers.

A case in point is the dilemma faced by an East Coast manufacturer that had been successfully producing probes with 0.48-in.-diam machined housings for years. When the market required a reduced diameter size, the company found it had difficulty manufacturing the component by conventional methods.

The device manufacturer "needed a housing that had a diameter of 0.196 in. and a tight wall-thickness tolerance to hold the camera firmly in place," explains Paul Hazlitt, director of engineering for Servometer (Cedar Grove, NJ), an electroforming firm. "When the camera bundle was more than 0.250 in. in diameter, it was possible to machine the part with a tolerance of ±0.001 in. But with a smaller-diameter probe, that variation was too wide."

As uniform wall thickness is essential to the proper functioning of the camera, the manufacturer of the probe was forced to examine new production methods. When both accuracy and shape factors ruled out stamping, the company contacted Servometer to investigate electroforming.

"Electroforming is a precise process that can produce intricate parts with little variation, so we didn't have a problem producing the part with a tolerance of ±0.0005 in.," says Hazlitt. Manufactured from nickel, the Servometer housing operates in a temperature range of –25° to 125°C and protects the camera from moisture and chemicals, allowing the probe to be used in harsh environments.

Servometer estimates that it was able to produce prototype retainers for the company in about two weeks. Importantly, this production method allows for even further miniaturization. "We can maintain the required tolerance with part diameters as small as 0.030 in.," says Hazlitt.

After successful ISO and USP Class VI testing, the camera probe company adopted Servometer's electroformed housing as the standard casing for cameras with diameters smaller than 0.25 in. Though electroformed components cost slightly more than other units, the company notes that the reliably tight tolerance allows technicians to spend less time inspecting, testing, and adjusting the cameras once they are inserted.

A reduction in the number of rejected components and a zero field failure rate are also cited as cost-offsetting factors. According to Servometer, the electroforming process could bring similar benefits to a range of other products. "This process is also suited for instrumentation components, flexible couplings, and surgical devices," says Hazlitt.

Zachary Turke

Copyright ©2002 Medical Product Manufacturing News