PRODUCT UPDATE
Testing Equipment:
An Essential Tool in Quality Control
Norbert Sparrow
International standards, validation requirements spur need for appropriate testing instruments.
The widespread use of international standards has had a significant impact on the way in which medical devices are designed and manufactured. It has also engendered a reliance on testing equipment as a means to show that the product lives up to the claims made by the manufacturer. Industry needs to live by the "golden rule," says Stephen Franks, executive vice president of T.M. Electronics (Worcester, MA, USA), a supplier of testing equipment. "If you can't measure it, you can't control it." He cites ISO 11607 for the packaging of terminally sterilized medical devices as a recent example of how standards organizations and manufacturers of testing equipment achieve a common goal.
"ISO 11607 has done a good job of putting on paper what we and other people have been preaching for years: you have to measure and document your process . . . in essence, to validate it," says Franks. "ISO 11607 lays out the sequence of things that you need to look at, and one of its requirements is that seal strength be measured." T.M. Electronics recently introduced a medical package tester that performs this task in accordance with the guidelines set down by the standard.
"It all started with the ISO standards—that was the defining moment," says Monika Löffler, product manager at melab Medizintechnik und Labor GmbH (Kernen, Germany), a supplier of load-measuring, leak-testing, tip-testing, and automated testing and assembly systems to the medical device industry. Companies began seriously investing in testing equipment when it became apparent that resisting the trend would result in "higher failure rates and lower output," she says. "Today, you have no alternative but to prove the quality of your product."
Quality Brings Competitive Edge
Industry's move toward outsourcing and contract manufacturing has also contributed to a demand for testing equipment, according to Mark Curtis of Vision Engineering (Send, Surrey, UK), a supplier of optical inspection systems to a variety of industrial sectors. Manufacturers are applying the use of standards much more rigorously as a way to ensure that quality does not suffer even as production is increasingly parcelled out, says Curtis, who has watched his company's share of clients involved in device manufacturing mushroom in recent years.
Curtis adds that manufacturers may have another compelling reason to invest in appropriate testing equipment. "The device market—especially in the area of stents, needles, catheters, and such—has become much more competitive. The days when you could attract business by dropping prices are over," he says. "Manufacturers have reached a stage where it's no longer feasible to make things for less money, and that leaves only one other area where they can compete—quality."
Considering public awareness of HIV and hepatitis, needles are a good example of how the focus of industry has shifted, Curtis adds. "For a lot of our customers, needles have gone from being a sideline to a core part of their business, and the best way for them to compete is by being able to say [and prove] that their needle is better than alternative products."
Medica S.r.l. (Medolla, MO, Italy), a supplier of leak-testing equipment to the medical device industry, has observed another trend among its clientele: a demand for a precisely calibrated instrument. In recent years the company has channelled its efforts into meeting this need. "Calibration was not as important seven or eight years ago as it is today," says sales manager Paolo Galavotti, who notes that all of Medica's leak testers are delivered with calibration and certification documents.
Coming Soon: Testing Network
The ability to connect several testers to one central unit and to download and analyze information from a number of sources is the wave of the future, according to Galavotti. He takes his vision a step further by outlining how testing equipment might fit into a cleanroom production facility in the years ahead.
"The leak testers will be part of a network, interconnected by a serial interface, that encompasses all of the other manufacturing and process equipment. This will optimize productivity, centralize control of all of the production steps, and facilitate management of routine maintenance of process equipment," says Galavotti. Leak testers themselves, he adds, will undergo an evolution similar to the one experienced by medical equipment. "You will see a more intuitive interface, built-in help functions, and an increasing number of self-diagnostic features."
While the seamlessly interconnected cleanroom may not yet be in reach, suppliers of testing equipment continue to develop instruments that are both more technologically sophisticated and simpler to operate than previous models. Leading companies that produce equipment with specific applications for the medical device industry, as well as their most recent products, are profiled below.
DTE
Nondestructive leak testers for OEM use monitor the electrical field generated between corona electrodes to perform precise tests in the millisecond range, even with form-unstable parts. Empty components are tested by placing one electrode on the outside of the container and another on the inside; for filled components, both electrodes are placed on the outside. The latter method requires an electrically conductive liquid, but its conductive property can be as low as 1 mS/cm. The minimal energy of the electrical discharge prevents the material from heating up.
In the event the total average increase of leakage current does not allow for a safe detection process, the company has also developed a fibre-optic-based photoamplifier unit that monitors the increase of radiated light. This is suited for the testing of small filled-glass or plastic ampoules.
The corona discharge equipment that we have developed for leak testing has numerous potential uses," says Bent Sorensen, general manager at DTE (Lunderskov, Denmark), "but it was developed primarily for medical device testing purposes."
Because the system identifies a hole by counting the number of electrons that pass through, it is capable of detecting apertures down to less than 1 µm in real time. "This is very useful for latex products, for example, or thin-walled items where you immediately see where the leakage is occurring," says Sorensen. And the system is very fast, he adds. "The testing time can be as little as 5 or 6 milliseconds; maximum duration is 100 milliseconds."
The machine allows the simultaneous execution of four individual testing programs and automatically initiates reject signals. Test results and calibration data can be stored and documented to comply with EU and US guidelines.
T.M. Electronics
An automated package tester provides seal-strength and leak-test modes to ensure that flexible medical packaging maintains its validated seal strength in process and final packages according to ISO 11607. The standard for terminally sterilized medical devices requires that adhesive-coated materials such as those found in peelable seals for medical packages have a minimum specified seal strength and that packages meet the producer's specifications.
The BT-1000 can perform whole-package inflation tests for burst seal strength and seal creep resistance in seconds without requiring sample preparation. "The machine can do simultaneous testing of all the seals and, under the right conditions, it can detect your seal strength area," says Stephen Franks, executive vice president of T.M. Electronics (Worcester, MA, USA). "It also provides you with quantitative data that you can relate to your process or product parameter specifications."
The automatic benchtop instrument provides ISO 11607–recognized measurements for burst strength and creep resistance as well as leak tests for package integrity in nonporous materials. Eight test modes are available, and a large LCD shows the actual pressure versus time response for each test. The BT-1000 also analyzes the test data and generates a graphic output that includes control charts, histogram and statistical mean, standard deviation, and maximum and minimum range for statistical quality control purposes. Data can be printed or downloaded by means of the RS-232 port.
Hounsfield Test Equipment Ltd.
A supplier of testing equipment to a wide spectrum of industries with core activities in the textiles, plastics, and rubbers sectors recently developed a machine to test the tensile strength of medical sutures. The machine was designed to replace a UK manufacturer's mechanical method for testing sutures to a predetermined pulling. The mechanical method yielded excellent results, according to John Ivory, technical director at Hounsfield Test Equipment Ltd. (Salfords, Surrey, UK), but it had limitations. In particular, it did not indicate the load at which failure occurred and it lacked a safeguard that would prevent overstretched sutures from passing the test.
"The company had been using a machine that worked with a cantilevered weight," says Ivory. "The problem they encountered with this method was that at the moment of inertia there was a possibility of overstretching and perhaps damaging the product." Hounsfield developed an electronic tester with programmable targets and a fail function in the event of overstretching. "If the operator pulls the suture past a point where damage could occur, the machine indicates that it has failed," says Ivory.
In addition, the LS100 has no point of inertia and indicates the precise load at which failure occurs. "The specifications also called for a durable and reliable machine that was accurately calibrated and that would be able to store the information so that it could be downloaded at the end of the day for quality control procedures," says Ivory. "Obviously, cost was also an issue."
The benchtop tester also boasts high-speed test throughput and accommodates force measurements from 1 to 100 N with ±0.1% accuracy. It can store 1000 test results; pass/fail results are indicated by one audio and two visual signals.
Indentec Hardness Testing Machines Ltd.
The Vickers test determines hardness by making an indentation in the material to be tested by means of a pyramid-shaped diamond. "Looking at the impression requires an optical device," says managing director Trevor Sidaway of Indentec Hardness Testing Machines Ltd. (Lye, W Midlands, UK). "That device used to be a microscope, but video-based systems have gained in popularity because they are able to do this much faster."
Indentec has introduced a video-based Vickers system that can be incorporated into the company's entire range of Vickers testing equipment. "You can measure the impression automatically by adding a frame grabber or by overlaid graticules," says Sidaway. The graticules are positioned using a mouse and downloaded to the built-in software, which calculates the hardness number and displays it on both the monitor and touch screen.
The system's ability to magnify the indentation up to 440X and the easy positioning of the graticules enable measurements to 0.1-µm resolution and better.
feinfocus Medizintechnik GmbH
A worldwide supplier of industrial x-ray systems that recently focused its efforts on the medical device sector has developed a radiography system with applications in nondestructive materials testing for such products as pacemakers, heart valves, and related components. The DIMA Soft P41 incorporates a 10-µm lifetime x-ray source operating in the 15–100-kV range; it produces high-resolution radiographs up to 100 lp/mm with unlimited depth of field. "Images can be magnified up to 20X," says Friedhelm Maur, marketing director at feinfocus Medizintechnik GmbH (Garbsen, Germany), "and the system is capable of resolving material features as small as 5 µm."
Another advantage of the DIMA Soft P41, according to Maur, is its open x-ray source design. "When a conventional tube wears out, you generally have to replace the entire tube, which can cost in the neighborhood of US$10,000," says Maur. "With our tube, you just open four little screws and replace the part that is defective." The open design also allows the user to select from a wide range of interchangeable target materials including copper, molybdenum, and tungsten.
The unit is suited for failure analysis, quality control, and quality assurance operations on various medical subassemblies and devices. The company also offers testing and inspection services at its German and US facilities.
Ai Qualitek
A benchtop leak tester for medical device manufacturers performs integrity, burst, seal-strength, and creep tests. Pressure decay technology is used to detect and measure leaks at a resolution of 0.01 mbar; the unit features programmable reject levels of 0.01 to ±19.9 mbar and a choice of pressure ranges up to 15 bar. The Q631 also performs burst and creep testing on flexible packaging, thus ensuring that the product and packaging are both leak-free, a particular concern when devices must be packaged and maintained in sterile conditions.
"In addition to its small footprint and enhanced ergonomic features," says Paul Sharpe, business development manager at Ai Qualitek (Pampisford, Cambs, UK), "another advantage of the unit is the easy installation. It takes less than one minute to set up, which is a real plus for companies that test a variety of products." Four different product-specific tests can be stored, he adds, and a front-mounted key-operated switch prevents accidental alteration of the testing parameters.
The company will also be launching a tester for blister packs that should be commercially available by July. "The tester will electronically and automatically show by means of computer graphics the part that is leaking and by how much, and it will provide full quality assurance data," says Sharpe. It was shown at Packex in Birmingham in March and is currently being used at beta sites in the UK.
Vision Engineering
A company that specializes in optical inspection systems recently developed a microscope using high-resolution stereo optical technology suited for demanding quality control procedures. The company's Expanded Pupil (EP) technology allows full freedom of head movement both laterally and in terms of distance without affecting the full-field high-resolution stereo image. "The ability to inspect three-dimensional features at standard 640The company also supplies low-magnification stereo optical systems without eyepieces. The Manta range is used extensively in dental labs, according to Curtis, and is suited for manipulative tasks such as finishing, polishing, and drilling. "The Dynascope range, which is also eyepieceless," says Curtis, "can be used for putting sutures into ocular needles and checking angle grinds, for example."
Tecna
An electronics laboratory located in Italy's Modena region, which is noted for its concentration of medical device OEMs and suppliers, Tecna (Medolla, MO) has designed a master leak simulator that calibrates and certifies leak tester performance. "The LTC, or leak tester control, is used to verify that the testing instrument is properly detecting the cubic-centimeters-per-minute air leaks at the programmed test pressure," says technical manager Sergio Lodi. It is an example, he adds, of the company's commitment to innovation in the medical device testing arena.
Tecna's Provaset line of leak testers are used worldwide, adds Lodi, to verify the integrity of blood lines, filters, pouches, and related products. For pressure and flow rate procedures, the company offers Delta P/F equipment that is suited for use with catheters, filters, valves, multilumen tubing, membranes, and so forth. The basic model incorporates an electronic porosity meter that tests the porosity of membranes or papers based on the Gurley and Bendtsen methods. Testers with identical performance characteristics are available for use with automated assembly equipment and applications that require multiple parallel test points.
Medica S.r.l.
Leak testers built specifically for manufacturers of medical devices have been developed using an integrated design concept. Each component of the P-Test series of testers is either approved by a notified body or supplied by an ISO 9000–certified firm. In addition, the hardware has been redesigned to prevent damage caused by short circuits or power surges, the software uses Flash EPROM programming for improved project management and more upgrade options, and the pneumatic circuit is designed to withstand hundreds of thousands of test cycles. Before being shipped to the customer, adds Paolo Galavotti, sales manager at Medica S.r.l. (Medolla, MO, Italy), quality and performance controls are performed on each leak tester. "Since 1992, we have included with each leak tester a document stating that calibration has been performed with a traceable instrument certified periodically by a pressure-measurement notified body."
The P-Test series of instruments are suited for air pressure decay leak testing of elastic or rigid medical devices such as blood lines, infusion and transfusion sets, bags, filters, oxygenators, heat exchangers, reservoirs, stopcocks, and related products. The testers can be used on a production line as well as in quality assurance and R&D departments. Three different models are available for varying applications.
Lloyd Instruments Ltd.
"As more and more plastics are used in an ever-increasing range of medical products—including home diagnostic kits—testing standards are becoming more stringent," says Karen Hately, Davenport product manager at Lloyd Instruments Ltd. (Fareham, Hants, UK). "It is therefore vital that these standards be adhered to and that manufacturers achieve repeatable and reproducible results." According to Hately, Lloyd Instruments is well positioned to supply a broad range of testing equipment to help medical device makers achieve this goal.
Thermoplastic materials used in medical packaging, syringes, IV drip chambers, and related products can be efficiently tested by means of the Davenport MFI-10, which measures melt flow rate and melt volume rate. According to independently conducted tests by two of the largest global polyethylene resin suppliers, the testing device produced results with less than 1% variance using standard polymers from MFI 2–20 g/10min. Optional features include an automatic flow rate timer, weight loader, and cutoff.
The company recently introduced software that interfaces with its materials-testing systems to enable rapid testing of devices and raw materials. Nexygen, which is Windows 95 and NT compatible, contains an extensive library of standard and user-definable tests, and features easy integration of results into documents and reports. One advantage of the software, says Hately, is that "many analyses can be carried out by two key presses." Among tests that can be conducted on medical devices and packaging, Hately cites the measurement of needle sharpness and strength of catheters, tubing, and blisters.
The company also supplies low-force materials testers that can be controlled by either a console or computer. Available with a wide selection of grips, jigs, and related accessories, the LF500 and LRX units are suited, respectively, for testing up to 500 N and 2.5 kN.
Mark-10 Corp.
A digital bottle-cap torque sensor is used primarily to test the torque necessary to apply or remove a bottle cap but has numerous other applications, according to Vera Sabov, marketing manager at Mark-10 Corp. (Hicksville, NY, USA). The Model STB can be used to measure the torque in breakaway fasteners and valve operations and to calibrate torque tools. A universal gripping mechanism can accommodate a wide variety of irregularly shaped items. The device connects with the company's Model BGI digital force and torque indicator and, as a system, features a 4.5-digit LCD, peak torque memory in clockwise and counterclockwise directions, selectable units of measure, and bidirectional RS-232 capabilities.
The company offers a range of other force and torque measurement products that have applications in the medical device manufacturing field, including units suited for suture strength testing and needle penetration force measurement. In addition to its standard line, the company can satisfy most special and OEM requirements.
melab Medizintechnik und Labor GmbH
In-line load-measuring and tip-testing equipment developed by melab Medizintechnik und Labor GmbH (Kernen, Germany) is designed to inspect the quality and integrity of needle tips during the production process. One advantage of the Dekamat load-measuring machine over comparable equipment, according to product manager Monika Löffler, resides in its recording capability. "With a 100% controlled in-line machine, you can easily locate systemic failures and weak links in the production process." Recorded data also optimize quality assurance, Löffler notes. "Automatic data recording makes it easier to prove the quality of your product to customers and it frees up personnel that are currently writing and maintaining validation data by hand."
For penetration load measurement of medical needles, surgical blades, biopsy punches, and related devices, the company supplies the Deka machine. One application involves determining the load necessary to move a syringe plunger in a prefilled syringe. It can also be used to perform bending and kinking tests on needles and electrodes and to check seal strength in blister packaging.
The company also supplies an automated testing and assembly system designed for checking the bevel, orientation, and sharpness of a needle, setting the needle protector, and sorting defective products. A variety of other load-measuring equipment and leak testers are also available, and the company also offers testing services at its German facility.
