QV Active surface analysis of a bone screw.
PHOTOS COURTESY OF MITUTOYO AMERICA CORP.

Life-saving devices and quality-of-life devices – such as stents, implants, and surgical tools – must be produced in higher volumes to meet the needs of aging populations, all but ensuring innovations will continue to be a fundamental aspect in the medical marketplace.

Demand for innovations increases as the margin of error in design and performance decreases tangentially. This creates a tough challenge for medical device manufacturers to increase company financial performance and product capacity while maintaining product durability.

Simply stated, there can be no loss of precision while designing and creating intricate, multi-faceted products. This is where metrology innovations come into play – ensuring fast, highly accurate precision measurements maintains quality and tolerances for safe, reliabile medical devices

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The biggest advancement in precision metrology is 3D vision measurement technology. Traditional 2D vision measuring equipment easily measures flat pieces with limited Z-axis capabilities. The latest 3D vision measurement systems use advanced image processing and development, processing power, and new camera optical designs that eliminate antiquated frame grabber hardware to scan larger images while processing millions of points with 1.5µm accuracy and 0.02µm resolution. Some vision machines achieve 0.8µm and 0.25µm accuracy.

Z-axis measurement by a vision machine.
PHOTO COURTESY OF MITUTOYO AMERICA CORP.

A coordinate measuring machine (CMM) can measure parts with more accuracy, however, 3D vision measuring systems can measure the same features much faster and offer important surface details a CMM could not. For example, recently a company in the nuclear medicine technology industry was in search of quality assurance solutions on a key part of a new medical device that featured many different surfaces including multiple diameters, bore depth, and internal groove measurements.

A CMM can accurately measure these dimensions, but the process would be time consuming and labor intensive. A vision machine could provide equivalent accuracy in a much quicker period. With this knowledge, the company implemented a CNC vision measurement system with a high-resolution CMOS color camera and active touch probe to measure all dimensions of the part, including the internal groove measurements, in 1 minute, 29 seconds (including part alignment).

This type of 3D measurement technology suits medical segments such as implants, needles, catheters, and orthopedics. Orthopedic device manufacturers can greatly increase throughput while maintaining tight quality control on much smaller medical hardware such as bone screws. Using the points from focus (PFF) principle for optical data collection, a region of interest, such as a single thread on a bone screw, can be selected, images captured, and an image stack on the Z-axis built to create a 3D topography from the pixel data. The topographical map is then sectioned where measurements, chamfers, and surface attributes such as burrs or anomalies can be accurately captured and analyzed. All analysis and measurements occur in a fraction of the time.

PHOTOS COURTESY OF MITUTOYO AMERICA CORP.

A vision measurement system has a much longer depth of field – the physical space between the target and optics – than a stereo microscope. With this larger depth of field, the system can measure different types of products in a wider range of sizes, giving device manufacturers the ability to measure their catalog of bone screws and their implant products. Quality analysts and engineers only need to be trained on a single machine instead of multiple machines for multiple products, narrowing the window of human-based and machine-based errors.

While retaining quality assurance for medical devices and parts and increasing speed of dimensional measurement and throughput without sacrificing accuracy, 3D vision measurement systems allow medical device makers to design and build device prototypes. Speeding prototype design allows device makers to prove new concepts of future devices, discover flaws earlier in the process, find the need for change, incorporate those changes quickly, and save time.

Right: Enhanced image of bone screw measurement and contour analysis.
PHOTOS COURTESY OF MITUTOYO AMERICA CORP.
The Quick Vision Active
PHOTO COURTESY OF MITUTOYO AMERICA CORP.

The medical patient receiving an implant benefits from the advancement in vision measurement technology. Faster, accurate device measurements provide patient-specific designs for a customized, more comfortable fit. And with the recent and growing trend of on-demand 3D printing implants, accurate measurement and quality assurance have never been more important.

Mitutoyo America Corp.
https://www.mitutoyo.com