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On the safe side with incorruptible inspectors

Many medtech companies only feel they are on the safe side when they have been awarded a seal of approval. Quite justifiably. Because modern measurement equipment must meet the standards imposed by seamless quality assurance and ensure that the company is spared unfounded complaints. No one in the business can afford to have production faults.
Seen through the fibre-optic interferometer, the world looks quite different. Even if it is only a tiny scrap of skin tissue, the fine cracks are still unmistakable.

The procedure which reliably makes every defect visible is known as optical coherence tomography (OCT) and was developed by the Fraunhofer Institute of Production Technology (IPT) to make it fit for purpose as an inspection system.
The OCT system is classed as a tomographic imaging procedure and it examines structures close to the surface up to a depth of three millimetres. Because the detector camera has such a high-resolution capacity – the light source detects structures from 50 nanometres – OCT measurements are one of the quality assurance processes in high demand. The measurement procedure can be automated and is used, for example, to check skin transplants and deliver a measurement report.

Investments in measurement and review technology pay dividends for medtech companies. Devices and components are constantly increasing in complexity, while advances in implant production, for anything from knee to dental replacements, pose fresh challenges for materials and component auditors. The sheer volume of measurement data increases with each new product generation, and quality tolerances are often in the micro and nanometre ranges.
Although many implants – for example knee, hip and finger joint and even tooth replacements – are subject to dynamic stresses, measurements are generally only available for static stresses. In the view of test machine manufacturer Dyna-Mess, component audits should also cover such dynamic values as fatigue endurance limits and materials fatigue. For example, with dental implants, many patient complaints relate to subcritical crack propagation which had remained undetected in static testing.

No need for hydraulic fluid
According to Dyna-Mess, servopneumatic test machines, which realistically map the forces and frequencies of biomedical applications, represent a precise and cost-effective measurement solution. Servopneumatic test machines are well suited to laboratory operation because they need no hydraulic fluid – the compressed air system already available is sufficient. Unlike hydraulic machines, they need no continuously operational pump. As a result, they function quietly, save energy and do not need to be cooled.  

A further advantage is the standard specification. The machines already contain the measurement technology for force and displacement as well as interfaces for external connections, so they can register, store and document other measurement scales, such as temperature. It is even possible to communicate with cameras in order to detect fractures, for example. Any measurement technician can set the machine configuration to follow periodic load curves or simulate ageing processes, among other things.Careful quality checks are a must
Careful quality checks are a must for every implant manufacturer of stents for insertion in human blood vessels and organs. The small tubular lattice structures of these tissue supports generally consist of special metal alloys. In some applications, the ends are expanded conically. The small strut widths are particularly problematic since the tolerances are in the micrometre range.  Coordinate measurement devices are ideally suited to the automatic measurement of strut angles, widths and thicknesses and stent lengths. To address this, Werth Messtechnik has equipped its multisensor coordinate measurement machine with special transmitted light illumination and a high-precision rotation axis. Inspections are carried out via sensory imaging and evaluation. For larger cylinder jacket areas there is additional scanner software that displays the result as a two-dimensional image.  Companies anticipate that another trend in measurement technology will deliver significant benefits in efficient quality assurance as regards the time and costs involved. Inline inspection entails measurement tasks and production process that are closely interlinked, which leads not only to considerably shorter measurement cycles, with more rapid component inspection, but also to significantly earlier process adjustments. The Medictube inspection system from Pixargus, for example, delivers optical inline inspection of tubes used in medicine for heart catheters or dialysis. Even transparent and extremely thin tubes with external diameters of half a millimetre are no problem for this system. According to the manufacturer’s information, it has designed the test system so that tubes are subject to real time 100% inspection during production for holes, cracks, inconsistencies, foreign particles or inclusions, with the automatic removal of defective material.  The enhanced performance of the systems is based on technical improvements to individual components and innovative engineering. The result is that today measurement head resolution with 8 megapixel cameras is forging ahead into the 20 micrometre range and the scanning frequency of contactless line scan cameras can be as high as 36 kilohertz. That is sufficient to carry out very precise inspections at even high production speeds. The new autofocus optic ensures that the system images the tube optimally on the camera chip under all operational conditions.

There are also significant innovation advances in software and the performance capability of current PC technology. Homogenous data on the measurement process and a variety of control and evaluation functions generate images that are extremely detailed. At the same, image processing methods continue to improve. Reflections caused by shiny tube material surfaces are no longer an obstacle for optical inline systems.  Modern measurement and test systems open up completely new perspectives for machine throughput, scrap reduction and process cost minimisation. This is flanked by compact construction with low installation length and numerous options for adaptation into existing production lines. Particularly attractive to users is the fact that the necessary investments pay for themselves after only a few months of operation.
Andreas Beuthner  

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German Summary
Nur mit Prüfsiegel fühlen sich viele Medtech-Companies auf der sicheren Seite. Mit Recht. Modernes Messequipment erfüllt die Maßstäbe einer lückenlosen Qualitätssicherung und entlastet das Unternehmen vor ungerechtfertigten Reklamationen. Denn Produktionsfehler kann sich niemand in der Branche leisten. Der deutschsprachige Beitrag ist nachzulesen auf www.meditec-international.com/medi0611mess