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Articles from 1998 In April


Seven Basic Tools That Can Improve Quality

Hitoshi Kume, a recipient of the 1989 Deming Prize for use of quality principles, defines problems as "undesirable results of a job." Quality improvement efforts work best when problems are addressed systematically using a consistent and analytic approach; the methodology shouldn't change just because the problem changes. Keeping the steps to problem-solving simple allows workers to learn the process and how to use the tools effectively.

Easy to implement and follow up, the most commonly used and well-known quality process is the plan/do/check/act (PDCA) cycle (Figure 1). Other processes are a takeoff of this method, much in the way that computers today are takeoffs of the original IBM system. The PDCA cycle promotes continuous improvement and should thus be visualized as a spiral instead of a closed circle.

Another popular quality improvement process is the six-step PROFIT model in which the acronym stands for:

P = Problem definition.

R = Root cause identification and analysis.

O = Optimal solution based on root cause(s).

F = Finalize how the corrective action will be implemented.

I = Implement the plan.

T = Track the effectiveness of the implementation and verify that the desired results are met.

If the desired results are not met, the cycle is repeated. Both the PDCA and the PROFIT models can be used for problem solving as well as for continuous quality improvement. In companies that follow total quality principles, whichever model is chosen should be used consistently in every department or function in which quality improvement teams are working.

Figure 1. The most common process for quality improvement is the plan/do/check/act cycle outlined above. The cycle promotes continuous improvement and should be thought of as a spiral, not a circle.
 

SEVEN BASIC TOOLS

Once the basic problem-solving or quality improvement process is understood, the addition of quality tools can make the process proceed more quickly and systematically. Seven simple tools can be used by any professional to ease the quality improvement process: flowcharts, check sheets, Pareto diagrams, cause and effect diagrams, histograms, scatter diagrams, and control charts. (Some books describe a graph instead of a flowchart as one of the seven tools.)

The concept behind the seven basic tools came from Kaoru Ishikawa, a renowned quality expert from Japan. According to Ishikawa, 95% of quality-related problems can be resolved with these basic tools. The key to successful problem resolution is the ability to identify the problem, use the appropriate tools based on the nature of the problem, and communicate the solution quickly to others. Inexperienced personnel might do best by starting with the Pareto chart and the cause and effect diagram before tackling the use of the other tools. Those two tools are used most widely by quality improvement teams.

FLOWCHARTS

Flowcharts describe a process in as much detail as possible by graphically displaying the steps in proper sequence. A good flowchart should show all process steps under analysis by the quality improvement team, identify critical process points for control, suggest areas for further improvement, and help explain and solve a problem.

The flowchart in Figure 2 illustrates a simple production process in which parts are received, inspected, and sent to subassembly operations and painting. After completing this loop, the parts can be shipped as subassemblies after passing a final test or they can complete a second cycle consisting of final assembly, inspection and testing, painting, final testing, and shipping.

Figure 2. A basic production process flowchart displays several paths a part can travel from the time it hits the receiving dock to final shipping.
 

Flowcharts can be simple, such as the one featured in Figure 2, or they can be made up of numerous boxes, symbols, and if/then directional steps. In more complex versions, flowcharts indicate the process steps in the appropriate sequence, the conditions in those steps, and the related constraints by using elements such as arrows, yes/no choices, or if/then statements.

CHECK SHEETS

Check sheets help organize data by category. They show how many times each particular value occurs, and their information is increasingly helpful as more data are collected. More than 50 observations should be available to be charted for this tool to be really useful. Check sheets minimize clerical work since the operator merely adds a mark to the tally on the prepared sheet rather than writing out a figure (Figure 3). By showing the frequency of a particular defect (e.g., in a molded part) and how often it occurs in a specific location, check sheets help operators spot problems. The check sheet example shows a list of molded part defects on a production line covering a week's time. One can easily see where to set priorities based on results shown on this check sheet. Assuming the production flow is the same on each day, the part with the largest number of defects carries the highest priority for correction.

Figure 3. Because it clearly organizes data, a check sheet is the easiest way to track information.
 

PARETO DIAGRAMS

The Pareto diagram is named after Vilfredo Pareto, a 19th-century Italian economist who postulated that a large share of wealth is owned by a small percentage of the population. This basic principle translates well into quality problems—most quality problems result from a small number of causes. Quality experts often refer to the principle as the 80-20 rule; that is, 80% of problems are caused by 20% of the potential sources.

A Pareto diagram puts data in a hierarchical order (Figure 4), which allows the most significant problems to be corrected first. The Pareto analysis technique is used primarily to identify and evaluate nonconformities, although it can summarize all types of data. It is perhaps the diagram most often used in management presentations.

Figure 4. By rearranging random data, a Pareto diagram identifies and ranks nonconformities in the quality process in descending order.
 

To create a Pareto diagram, the operator collects random data, regroups the categories in order of frequency, and creates a bar graph based on the results.

CAUSE AND EFFECT DIAGRAMS

The cause and effect diagram is sometimes called an Ishikawa diagram after its inventor. It is also known as a fish bone diagram because of its shape. A cause and effect diagram describes a relationship between variables. The undesirable outcome is shown as effect, and related causes are shown as leading to, or potentially leading to, the said effect. This popular tool has one severe limitation, however, in that users can overlook important, complex interactions between causes. Thus, if a problem is caused by a combination of factors, it is difficult to use this tool to depict and solve it.

A fish bone diagram displays all contributing factors and their relationships to the outcome to identify areas where data should be collected and analyzed. The major areas of potential causes are shown as the main bones, e.g., materials, methods, people, measurement, machines, and design (Figure 5). Later, the subareas are depicted. Thorough analysis of each cause can eliminate causes one by one, and the most probable root cause can be selected for corrective action. Quantitative information can also be used to prioritize means for improvement, whether it be to machine, design, or operator.

Figure 5. Fish bone diagrams display the various possible causes of the final effect. Further analysis can prioritize them.
 

HISTOGRAMS

The histogram plots data in a frequency distribution table. What distinguishes the histogram from a check sheet is that its data are grouped into rows so that the identity of individual values is lost. Commonly used to present quality improvement data, histograms work best with small amounts of data that vary considerably. When used in process capability studies, histograms can display specification limits to show what portion of the data does not meet the specifications.

After the raw data are collected, they are grouped in value and frequency and plotted in a graphical form (Figure 6). A histogram's shape shows the nature of the distribution of the data, as well as central tendency (average) and variability. Specification limits can be used to display the capability of the process.

Figure 6. A histogram is an easy way to see the distribution of the data, its average, and variability.
 

SCATTER DIAGRAMS

A scatter diagram shows how two variables are related and is thus used to test for cause and effect relationships. It cannot prove that one variable causes the change in the other, only that a relationship exists and how strong it is. In a scatter diagram, the horizontal (x) axis represents the measurement values of one variable, and the vertical (y) axis represents the measurements of the second variable. Figure 7 shows part clearance values on the x-axis and the corresponding quantitative measurement values on the y-axis.

Figure 7. The plotted data points in a scatter diagram show the relationship between two variables.
 

CONTROL CHARTS

A control chart displays statistically determined upper and lower limits drawn on either side of a process average. This chart shows if the collected data are within upper and lower limits previously determined through statistical calculations of raw data from earlier trials.

The construction of a control chart is based on statistical principles and statistical distributions, particularly the normal distribution. When used in conjunction with a manufacturing process, such charts can indicate trends and signal when a process is out of control. The center line of a control chart represents an estimate of the process mean; the upper and lower critical limits are also indicated. The process results are monitored over time and should remain within the control limits; if they do not, an investigation is conducted for the causes and corrective action taken. A control chart helps determine variability so it can be reduced as much as is economically justifiable.

In preparing a control chart, the mean upper control limit (UCL) and lower control limit (LCL) of an approved process and its data are calculated. A blank control chart with mean UCL and LCL with no data points is created; data points are added as they are statistically calculated from the raw data.

Figure 8. Data points that fall outside the upper and lower control limits lead to investigation and correction of the process.
 

Figure 8 is based on 25 samples or subgroups. For each sample, which in this case consisted of five rods, measurements are taken of a quality characteristic (in this example, length). These data are then grouped in table form (as shown in the figure) and the average and range from each subgroup are calculated, as are the grand average and average of all ranges. These figures are used to calculate UCL and LCL. For the control chart in the example, the formula is ± A2R, where A2 is a constant determined by the table of constants for variable control charts. The constant is based on the subgroup sample size, which is five in this example.

CONCLUSION

Many people in the medical device manufacturing industry are undoubtedly familiar with many of these tools and know their application, advantages, and limitations. However, manufacturers must ensure that these tools are in place and being used to their full advantage as part of their quality system procedures. Flowcharts and check sheets are most valuable in identifying problems, whereas cause and effect diagrams, histograms, scatter diagrams, and control charts are used for problem analysis. Pareto diagrams are effective for both areas. By properly using these tools, the problem-solving process can be more efficient and more effective.

Those manufacturers who have mastered the seven basic tools described here may wish to further refine their quality improvement processes. A future article will discuss seven new tools: relations diagrams, affinity diagrams (K-J method), systematic diagrams, matrix diagrams, matrix data diagrams, process decision programs, and arrow diagrams. These seven tools are used less frequently and are more complicated.

Ashweni Sahni is director of quality and regulatory affairs at Minnetronix, Inc. (St. Paul, MN), and a member of MD&DI's editorial advisory board.


 

A Practical Guide to ISO 10993-5: Cytotoxicity

ISO 10993

Required for all types of medical devices, cytotoxicity testing is a key element of the international standards.

The international standards compiled as ISO 10993, and the FDA blue book memorandum (#G95-1) that is based on 10993-1, address the critical issue of ensuring device biocompatibility by identifying several types of tests for use in selecting device materials. Required for all types of devices, cellular toxicity testing is covered in 10993-5: "Tests for Cytotoxicity—In Vitro Methods." This standard presents a number of test methods designed to evaluate the acute adverse biological effects of extractables from medical device materials. In performing these tests, laboratory technicians culture mammalian cells, usually of mouse or human origin obtained from a commercial supplier, in flasks using nutrient culture media. (The Latin term in vitro refers to the culturing of cells "outside of the body," or literally "in glass.") The lab techniques involved are much like those used to grow bacteria. Cultured mammalian cells reproduce by cellular division and can be subcultured to produce multiple large flasks of cells for use in evaluating materials. This article in MD&DI's continuing series on ISO 10993 provides an overview of cytotoxicity testing and discusses the benefits of performing such procedures.

TEST METHODS

In standard cytotoxicity test methods, cell monolayers are grown to near confluence in flasks and are then exposed to test or control articles directly or indirectly by means of fluid extracts. In the elution test method, which is widely used, extracts are obtained by placing the test and control materials in separate cell culture media under standard conditions (for example, 3 cm2 or 0.2 g/ml of culture medium for 24 hours at 37°C). Each fluid extract obtained is then applied to a cultured-cell monolayer, replacing the medium that had nourished the cells to that point. In this way, test cells are supplied with a fresh nutrient medium containing extractables derived from the test article or control. The cultures are then returned to the 37°C incubator and periodically removed for microscopic examination at designated times for as long as three days. Cells are observed for visible signs of toxicity (such as a change in the size or appearance of cellular components or a disruption in their configuration) in response to the test and control materials (Figures 1 and 2).

Figure 1. A confluent monolayer (100 x magnification) of well-defined L929 mouse fibroblast cells exhibiting cell-to-cell contact. This appearance is indicative of a noncytotoxic (negative) response in the elution test method.
 

Figure 2. L929 mouse fibroblast cells (100 x magnification) that illustrate a positive cytotoxic reaction in the elution test method. The cells are grainy and lack normal cytoplasmic space; the considerable open areas between cells indicate that extensive cell lysis (disintegration) has occurred.
 

Alternatively, samples of test and control articles can be applied directly to monolayers of cells covered with nutrient medium or to a semisolid, nutrient agar overlayer that cushions the cells from any physical effects that may be caused by contact with the samples. During the subsequent incubation period, extractables from the samples will migrate into the nutrient medium or through the nutrient agar overlay to the underlying cells. After incubation, the monolayers are evaluated in terms of the presence or absence of a zone of cellular effects beneath and surrounding the sample (Figure 3). Extraction conditions in the overlay and direct contact methods are less rigorous than in the elution test. However, these methods are particularly useful if only very small quantities of samples are available or when only one surface of a material needs to be evaluated.

Figure 3. An agar diffusion flask containing a sample of positive control material. The discoloration that extends outward from the material indicates that the presence of the sample has caused the cells to lyse, losing the vital stain incorporated in the agar layer.
 

The elution and direct contact and overlay methods are described in the technical literature and in the U.S. Pharmacopeia as well as in ISO 10993-5. Two additional methods, although used much less frequently than the techniques mentioned above, are used sufficiently to require mention. In the inhibition-of-cell-growth method, saline extracts are added to cell suspensions, and the inhibitory effects on the cells of the extracts are determined by measuring the cell mass after a standard period of incubation. In the Japanese colony-forming assay, a specified number of cells are exposed to an extract from the test article or control; then, following incubation, colonies of cells are counted for the test and control samples. If fewer colonies are formed with the test-article extract than with the negative control, this is taken as evidence of cytotoxicity.

BENEFITS OF CYTOTOXICITY TESTING

Cytotoxicity testing is a rapid, standardized, sensitive, and inexpensive means to determine whether a material contains significant quantities of biologically harmful extractables. The high sensitivity of the tests is due to the isolation of the test cells in cultures and the absence of the protective mechanisms that assist cells within the body. A mammalian cell culture medium is the preferred extractant because it is a physiological solution capable of extracting a wide range of chemical structures, not just those soluble in water. Antibiotics can be added to the medium to eliminate potential interference from microbial contamination that may be present on the test material and control samples. Results of cytotoxicity tests correlate reasonably well with short-term implant studies. However, they do not necessarily correlate well with other standard tests of biocompatibility that are designed to examine specific end points (such as sensitization) or that use extracts prepared under more rigorous conditions (for example, at 121°C in saline or cottonseed oil).

Cytotoxicity test methods are useful for screening materials that may be used in medical devices because they serve to separate reactive from nonreactive materials, providing predictive evidence of material biocompatibility. The ISO 10993-1 standard, "Guidance on the Selection of Tests," considers these tests so important that they are prescribed for every type of medical device, along with sensitization and irritation testing. Cytotoxicity test methods are also useful for lot-to-lot comparison of materials, for determining whether a potential replacement material is equivalent to that currently being used, and for troubleshooting and exploring the significance of changes in manufacturing processes.

CONCLUSION

Testing for cytotoxicity is a good first step toward ensuring the biocompatibility of a medical device. A negative result indicates that a material is free of harmful extractables or has an insufficient quantity of them to cause acute effects under exaggerated conditions with isolated cells. However, it is certainly not, on its own merit, evidence that a material can be considered biocompatible—it is simply a first step. On the other hand, a positive cytotoxicity test result can be taken as an early warning sign that a material contains one or more extractable substances that could be of clinical importance. In such cases, further investigation is required to determine the utility of the material.

Richard F. Wallin, DVM, PhD, is the president and Edward F. Arscott is manager of microbiology at NAMSA (Northwood, OH).

Continue to part 2 of this series, Sensitization Testing.


Copyright ©1998 Medical Device & Diagnostic Industry

Products Featured on the cover of MPMN, April 1998

Products Featured on the cover of MPMN, April 1998

Plastic-shell connectors designed for medical instrumentation applications

A series of plastic-shell connectors offer up to 27 gold-plated contacts in an 18-mm-diam body. The 405-series connectors can handle thousands of sterilization cycles, resist chemicals, and withstand operating temperatures of 200°C or greater. The connectors' inherently insulated construction provides electrical isolation and shock protection. They are available with or without integral shielding for EMI/RFI-sensitive applications. The connectors, which feature a SureGrip design for foolproof operation, intermate with the company's metal-shell line. W.W. Fischer Inc., 115 Perimeter Ctr. Pl., Ste. 1060, Atlanta, GA 30346.



PTFE surface coatings offer controllable thicknesses down to submicron levels

A technological advance in thin-film surface coatings allows the low-temperature deposition of pure PTFE. The thickness of the molecularly bonded coatings can be controlled down to submicron levels. The result is a thin-film surface coating with good adhesion, electrical, and mechanical properties. It can be applied to most materials and a high-temperature cure is not necessary. No overspray or high buildup are required when using the coatings in tight dimensions. Typical applications include release, barrier, friction, and device coatings. Advanced Surface Engineering Inc., 5320 Enterprise St., Ste. L, Eldersburg, MD 21784.




Nylon compounds suitable for a variety of medical product applications

Flexible nylon compounds are capable of filling a void in flexural modulus data between 80,000 and 120,000 psi, while remaining dimensionally stable with minimal postextrusion shrinkage. The Fostalon 5000 compounds are fully compatible with radiopaque fillers such as barium, bismuth, and tungsten, making them suitable for such medical applications as catheters, hubs, and shafts. The compounds resist hydrolytic degradation and can accept standard marking and imprinting inks. Foster Corp., 329 Lake Rd., Dayville, CT 06241.



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Editor's Page

Editor's Page

Finalists Chosen for Medical Design Excellence Awards

Back in October, I announced here the first-ever Medical Design Excellence Awards. Now I'm pleased to inform you that the judging is complete and the finalists have been chosen.

A panel of six jurors evaluated more than 230 entries and chose 54 as finalists in the following categories: dental instruments and equipment; clinical laboratory products; electromedical and other diagnostic devices; home medical equipment; implant and replacement products; rehab and assistive technology products; self-care products; surgical equipment and instruments; general therapeutic health-care, critical-care, and emergency products; and components and materials for medical applications.

Three criteria were used by the judges in evaluating the submissions. The first criterion was functional improvement—specifically, benefits to user and patient. These included ease of use, training, comfort, fit, service access, safety, and improvement of health care, cost-effective manufacture, appropriate aesthetics, and user interface. The products were also judged for such benefits as reducing the cost of developing or manufacturing products, enhancing a product line, improving manufacture or distribution, opening new market segments, and making the device or resulting treatments more accessible to patients. Lastly, the products were evaluated for their level of innovation.

The judges were careful to base their evaluations on each product's individual merits. Some impressions that contributed to a product's final score included: designing so that the components act as integrated elements in the total product design; the use of technology to improve an existing product; addressing the needs of the patient and operator rather than forcing them to adapt to the equipment; creating a marriage of technology and ergonomics; sensitivity to the user and product image; creating well-designed packaging; designing well-conceived safety features; integrating appearance and function; and successfully resolving a complex set of user operation requirements.

In the category of materials and components for use in medical products, the judges had slightly different concerns. Some of the issues considered included the product's potential to allow further medical device miniaturization, the use of fewer assembly parts to improve manufacturability and to lower end-product cost, and simplification of functional operation and service.

The May issue of Medical Product Manufacturing News will feature a brief description of all 230 entries; winners will be highlighted in the July/August issue. A complete list of the finalists can be viewed on this site. Finalists' entries will be on display at the 16th annual MD&M East Conference and Exposition, June 2—4, 1998, in New York City. Many of the designers and manufacturers will also be available to discuss their products.

The winners will be announced at a gala dinner and awards ceremony on Wednesday, June 3, at the Plaza hotel. For information on attending, call Amy Allen at 310/392-5509. I hope to see you there.

Ursula Jones

ursula.jones@cancom.com

Equipment News: Testing and inspection

Equipment News: Testing and inspection

Custom leak testing equipment

A company manufactures customized leak testing equipment for the medical device industry. A recent project involved designing a dual-nested leak tester that could meet stringent guidelines for leakage and porosity. The dual-nest design enables one housing to be tested while the other nest is manually loaded or unloaded. The customer's requirement for operator ease of use was met by slaving the Uson-based leak tester to an Allen Bradley PLC that handles all machine function sequencing. The company specializes in custom equipment for similar assembly and testing needs. Automation Tool Co., P.O. Box 2649, Cookeville, TN 38502.


Video microscopes

A company offers two lines of video microscopes designed for video inspection in product manufacturing. The VM-40 and -60 Measurescopes use a newly designed video measuring head mounted on a microscope stand made of cast steel for excellent manual video inspection capability. Both models feature proprietary measuring optics that deliver sharp images over the entire field of view. Objectives ranging from 1 to 100x are available. Working envelopes range from 2 x 2 x 6 to 8 x 6 x 8 in. Users can custom configure systems from a selection of six stages and four stands. A linear scale built into the stands permits accurate measurement over the entire range of vertical motion. Both models feature an optical focus aid for accurate z-axis measurements. Nikon Inc., 1300 Walt Whitman Rd., Melville, NY 11747.


Digital bottle-cap torque tester

A digital torque tester measures the required application or removal torque of bottle caps for medical vials. Some of the other uses of the Model STB torque tester include measuring breakaway fastener, motor-stall, and valve-operating torque. A universal gripping mechanism accommodates a variety of round or irregularly shaped items. The tester also connects to the Model BGI digital torque indicator. The complete system features a 41/2-digit LCD with a multifunction set of annunciators, peak-torque memory in clockwise and counterclockwise directions, and selectable analog and digital filtering. Mark-10 Corp., 458 W. John St., Hicksville, NY 11801.


Optical measurement systems

Designed for fast, noncontact inspection of small, thin, delicate, or complex workpieces such as IC lead frame, PCB, or nonmetal components, a series of optical measurement systems feature drive speeds up to 8 in./sec (x- and y-axes) and 6 in./sec (z-axis). Acceleration is 3.2 ft/sec2. Quick Vision systems feature high-resolution CCD cameras with 380,000 pixels that produce a crisp magnified image on a CRT screen. An autofocus function provides high-accuracy height and depth measurement, and can be set for surface or edge focusing and specified according to surface texture. Four models of Quick Vision are available in different sizes with measuring ranges up to 24 (x-axis), 24 (y-axis), and 6 in. (z-axis). All have a resolution of 0.0002 in. Mitutoyo Measuring Systems, 965 Corporate Blvd., Aurora, IL 60504.


Video inspection system

The inspection of electronic, plastic, and metal parts used in medical device manufacturing is performed by a video inspection system. The SmartScope MVP system features a motorized zoom lens, manual or motorized x-y-z stages, substage and ring lights, software, and video edge detection. The x-y stage has manual fine adjustment controls, while the z stage has both coarse and fine adjustments. CNC software provides semiautomatic operation on manual systems and fully automatic operation on motorized systems. The units are available with measuring ranges of 8 x 6 x 6, 12 x 6 x 6, 18 x 18 x 6, or 24 x 18 x 6 in. Optical Gaging Products Inc., 850 Hudson Ave., Rochester, NY 14621.


Stent/graft tester

Ten-year FDA benchtop durability test requirements for stents and vascular grafts can be met in just weeks using the Model 9010 stent/graft tester. The patented design features high-performance electrodynamic pump technology and a laser-based measurement system. The tester is suitable for generating fatigue data used for PMA submittals and for the development of new designs. Standard features include a PC-based servo control system with real-time graphic displays and integrated data acquisition. The unit accommodates vascular devices ranging from 3 to 40 mm. EnduraTEC Systems Corp., 7557 Market Place Dr., Eden Prairie, MN 55344.


Tensile tester

A tensile tester has a measuring capacity up to 150 lb and a travel distance of 18 or 36 in. The LT-150 processes up to 500 samples per second with a speed accuracy of 0.2%, speed range from 0.002 to 40 in./min, and a displacement resolution of 0.001 in. The machine features simple menu-driven software and PC-based electronics. Suitable for testing lightweight materials such as medical disposables, tubing, adhesives, and film, the unit can be used for rapid determination of tensile strength, elongation at peak and break, maximum and average peel strength, static and kinetic friction, tensile energy, and compression measurements. Thwing-Albert Instrument Co., 10960 Dutton Rd., Philadelphia, PA 19154.


Tensile test system

A 0­500-lb tensile, cycle, and compression test system is suitable for testing adhesives, fiber, composites, ceramics, and other materials for QA, QC, and product evaluation. The AccuTest/502 system is designed for ease of use, with smart buttons, LCD for menu selection and programming, and two test result data displays to consolidate test control, setup, and data operations in one console. The machine can input and store seven test setups and six report graphics setups. Test results can be reviewed immediately and then printed or stored for later recall and graphing. The unit supports multiple load cells and provides built-in safety features, including load cell overrange and clamp compression. Physical Testing Equipment Services Inc., P.O. Box 19108, Johnston, RI 02919.


Optical measurement systems

A company makes noncontact optical measurement systems that incorporate aspects of optical comparators, toolmaker's microscopes, and coordinate measuring machines. Available in either manual or automatic versions, the systems are designed for dimensional analysis and inspection of such medical parts as stents, catheters, tubing, valves, syringes, and pacemakers. They measure piece parts for first-article, process control, or final inspection. The OMIS II (pictured) and -III series can be customized for specific applications. Systems feature Windows-based software and on-screen graphics. RAM Optical Instrumentation, 1791 Deere Ave., Irvine, CA 92606.


Microprocessor-based leak tester

A microprocessor-based leak tester is equipped with touch screen programming and multiple testing programs for different parts. The Testra model tester features fast testing speed with high repeatability. It can perform leak tests, flow tests, vacuum tests, functional tests, and more. Testing applications include tubing, IV administration sets, blood sets, filters, catheters, dialyzers, instruments, and oxygenators. Uson, 5215 Hollister, Houston, TX 77040.


Automated package tester

An automated package tester measures burst and creep test pressures and displays real-time performance characteristics. The Model BT-1000 machine displays a plot of pressure versus time on a large, blue-on-white LCD display. It features a leak testing mode for nonporous package film and foil materials; the instrument tests such materials in seconds. Statistical analysis of the built-in data log provides immediate access to data in process or validation performance runs. Data can be interfaced with existing programs through the RS-232 port or in printed output. T.M. Electronics Inc., 330 Tacoma St., Worcester, MA 01605.


Image acquisition system

A CCD-based image sensor uses patented image acquisition technology to deliver repeatability and image stability for high-speed on-line vision and inspection applications. The SmartImage sensor can perform precision measurement, blob analysis, SPC data output, motion control guidance, and 2-D code reading. The system comes complete with hardware, software, illumination, cabling, and training. DVT Corp., 1670 Oakbrook Dr., Ste. 330, Norcross, GA 30093.


Catheter tester

A multichannel catheter tester routes air to a catheter to test for outer-wall integrity, occlusion, and interlumen leaking. A luer connecting nest (LCN) ensures leaktight seals between the product and the Sprint-LC tester. The LCN, which uses spring-loaded holders riding on independent bearings, eliminates retraction force, provides easy maintenance, applies consistent force, and self-aligns. The tester features temperature-controlled pressure transducers in stainless-steel housings and micromachined mass-flow sensors for high speed, performance, and reliability. It can store 99 programs, and each program can be linked to any other program such that the user can conduct a variety of tests on the same product in one test sequence. Pressure ranges are from 1 to 500 psig, and flow ranges are from 1 sccm to 20 L/min. Available in 2, 3, or 4 channels, the Sprint-LC unit is suitable for medical device design engineers seeking test equipment that meets FDA and ISO calibration requirements. Industrial Data Systems, 2370 South 2700 West, Salt Lake City, UT 84119.

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Machine Vision System Achieves High Inspection Speeds

MPMN Hotline




New Equipment

Machine Vision System Achieves High Inspection Speeds

20,000 parts per minute can be inspected

A MACHINE VISION SYSTEM achieves inspection speeds in excess of 20,000 parts per minute without relying on any expensive, proprietary processors.

The Prophecy system consists of three major elements: a high-performance, half-slot PCI bus—based frame grabber; Sherlock 32, which is a 32-bit Windows-based software application; and an Intel Pentium host computer with MMX processor and Windows NT 4.0.

Prophecy was designed to provide a very high level of machine vision performance in a system that is easy to configure and run. According to Gary Wagner, president of Imaging Technology (Bedford, MA), "with Prophecy, even inexperienced users can quickly set up a vision application to perform such tasks as measuring dimensions, detecting flaws, verifying size and location, and ensuring that components are properly assembled."

The core of the system is the Sherlock 32, a 32-bit Windows-based software application. With Sherlock, no additional programming is required to configure most on-line gauging, inspection, assembly verification, and machine guidance tasks. In minutes, Sherlock 32 allows users to create powerful vision applications using gray-scale processing techniques that generate subpixel accuracies.

The system uses the company's own IC-PCI, a half-slot, high-speed PCI bus image capture board. According to the manufacturer, the IC-PCI is the fastest PCI bus frame grabber on the market, providing more than 90 MB/sec sustained data transfer rates to the host computer's memory via an onboard, high-speed, dual-ported frame buffer of 2 or 4 MB.

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Materials

Acrylic-Based Compound Aids in Reducing Visible Contaminants

Resin is clean, clear, and easy to process

THE GLOBAL MEDICAL DEVICE market is focused on reducing the amount of visible contaminants in disposable medical devices. As a result, U.S. medical device manufacturers face very stringent requirements in foreign markets, making it difficult to successfully supply those markets. An acrylic-based multipolymer compound recently developed by CYRO Industries (Rockaway, NJ) helps manufacturers to reduce such contaminants.

Because the Cyrolite G20 EF compound is exposed only to filtered air from manufacture to packaging, impurities are kept to less than 60 parts per billion. An innovative closed-loop filtering process permits continuous monitoring, ensuring cleanliness to 40 µm. The resin is also clean, clear, easy to process, and impact and gamma resistant.

The compound demonstrates 90% light transmission and 7% haze, and has a 1.515 refractive index. The average melt flow is 2.2 g in a 10-minute period at 230ºC. Other properties include a tensile strength of 6800 psi and an elongation of 4% at yield and 9.5% at break. Deflection temperature capability is 86°C at 264 psi.

According to CYRO Industries' technical manager Peter Colburn, "the cleanliness of Cyrolite G20 EF allows it to be used in medical device applications in all markets."

One medical device manufacturer reportedly experienced a tenfold reduction in rejected parts since switching to Cyrolite G20 EF. The product was subsequently introduced in the Japanese market and has enjoyed wide acceptance.

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New Technology

System Provides Nondestructive Testing of Porous Packages

Entire shipments can be tested for sterile integrity

TRUE TECHNOLOGY INC. (Newton, MA) has introduced the first system that provides objective, reliable, repeatable, and nondestructive quality control of the sterile integrity of medical device packages with porous, gas-permeable membranes. Such packages could include thermoformed trays with porous lids and flexible pouches with one porous side. The Sealcheck 210 also provides retrievable validation data, which protect manufacturers if the sterile integrity of their devices is challenged by subsequent handlers or end-users.

Until now, medical device manufacturers have had to rely on a variety of techniques that include visual inspection, dye penetration, microbial challenge, and burst testing. The first method is highly subjective, while the latter techniques destroy the packages they test. This means that only random samples can be taken and the sterile integrity of the untested packages shipped to customers cannot be verified.

The Sealcheck 210 reliably detects leaks across the seal as small as 0.001 to 0.002 in. diam—the size of a human hair. The test involves inserting the package into a test chamber and pressing start. A temporary barrier layer is applied over the package membrane using a special tape. Next, helium tracer gas is introduced into the package through a port in the barrier tape. A probe maps the helium concentration using a mass spectrometer leak detector, and reports the location of any leaks found, whether in the seal between the permeable membrane and the thermoformed tray (or pouch), or in the package walls themselves.

With information obtained by the Sealcheck 210, device manufacturers are able to effectively diagnose and correct the cause of the leak, ensuring that the sterile integrity of the packaging is intact.

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Industry Experts Make Presentations at MD&M West '98

MPMN Industry News

Industry Experts Make Presentations at MD&M West '98

More than 35 conference sessions held

The 7500 medical device manufacturers who attended the MD&M West '98 Conference and Exposition, held January 19—22 in Anaheim, CA, had plenty to see as over 4000 vendors exhibited their products and services. This year's show included pavilions featuring IVD suppliers, medical electronics, and design software and rapid prototyping. At the International Pavilion, attendees could meet with representatives from many nations to get advice on site selection and regulatory issues. Along with these many product and services exhibits, attendees had the chance to listen to industry experts speak at the more than 35 conference sessions that were held during the four-day event.

Regina E. Herzlinger, professor of business administration at Harvard University's Business School, gave the keynote address at the Medical Device Executive Forum. Herzlinger noted that businesses long recognized for their excellence in customer service—such as accounting firms and hotels—have one thing in common: a narrow focus. They limit the number of products they offer, but provide each of those products well. Similarly, "consumer-conscious" health care is characterized by specialized clinics that, like "focused factories," concentrate on particular ailments. As consumers naturally seek an "all-under-one-roof" service model, the market segmentation of the focused factory approach will result in a clustering of providers, creating a market-driven healthcare system.

"A Practical Look at Medical Electronics Design" examined light sources, sensing methodologies, and a new measurement circuit topology, highlighting the breadth of new developments in this field. "Clinicians need quick, inexpensive results," said Kevin Keilbach, senior electro-optical engineer at RELA (Boulder, CO). "They want to run simplified tests and diagnostics in their office that are less invasive to their patients." Device manufacturers are compelled to develop devices using components that deliver a solution. Keilbach's comparison of lights underscored the importance of selecting the appropriate lamp sources for portable clinical and diagnostic devices.

Asia continues to be an area of interest to device manufacturers looking for growing markets for their products. And despite the currency crises, the region—especially India—continues to experience growth. "While India is presently a small medical device market, it will become very large in the next decade," Pratap Khanwilkar of MedQuest Products Inc. (Salt Lake City) told attendees of a session titled "Effectively Targeting Emerging Markets to Expand Your Business." "The time to enter the Indian market is now. Establishment of a brand is critical for penetration of the market and for staying power." Khanwilkar noted that, with India's middle class expanding and the life expectancy having doubled since 1947, the market for medical devices looks promising—growing an impressive 20% annually.

Khanwilkar was more optimistic than the other speakers at the session who discussed the Asian economies and their recent economic turmoils. Nevertheless, James Chan, president of Asia Marketing and Management, a consulting firm that helps U.S. companies sell to Asian markets, said that the Korean medical device market exceeds $1 billion and is expected to grow 10 to 30% annually. Similarly, he noted that Taiwan buys $650 million in medical equipment annually, $200 million of which comes from U.S. manufacturers.

Also speaking at the session was Mohammed Adnan Saaid of the Malaysian Industrial Development Authority. When asked how the 60% drop in the value of Malaysia's currency would affect U.S. device exporters, he said, "It means you must be more competitive. But nevertheless, quality medical devices will always be in demand."

Despite regulatory hurdles and a challenging business environment, China can be a lucrative market for industrious device manufacturers. At the session titled "Effectively Targeting China to Expand Your Business," Lawrence Pemble, executive vice president of the U.S.-China Industrial Exchange Inc. (Bethesda, MD) said that there are real opportunities in China to make money, "but you have to roll up your shirtsleeves and take a real hands-on approach."

Bruce M. Quinn, commercial officer at the U.S. Embassy in Beijing, confirmed this, saying, "A growing and aging population, coupled with an ever-increasing standard of living, is sure to continue to fuel the demand for higher levels of medical care." The Chinese market, which is growing at an estimated 15% annual rate, is the second largest in Asia after Japan. For the past two years, half of the total market demand, which is estimated at more than $1 billion, has been met through imports. In 1996, U.S. manufacturers accounted for approxiametly 30% of medical equipment imports.

At a luncheon speech to attendees of the Medical Device Executive Forum, Congressman Joe Barton (R-TX), chairman of the Committee on Oversight and Investigations and a principal sponsor of the FDA Modernization Act of 1997, said continued oversight will play a major role in ensuring that FDA meets congressional expectations for reform. "We'll be holding oversight hearings during this spring and summer to review the agency's implementation of the FDA Modernization Act," he told the audience of device executives. Describing the process that led to signing of the act last November, Barton observed that congressional oversight has been an important factor in softening FDA behavior toward industry. "We've been told that FDA now has a new attitude in dealing with manufacturers, and this is largely because of the oversight that Congress has exercised over the past three years."

Industry experts outlined situations in which partnership might make good business sense during the session "Pros and Cons of Partnerships Between Early-Stage Companies and Medical Device Firms" at the Medical Device Executive Forum. "If your company has a limited number of decision makers and a highly differentiated product, it may make sense to partner with another company to take advantage of some benefits of such a relationship," said David W. Chonette, general partner of Brentwood Venture Capital (Irvine, CA). Such advantages might include obtaining financing, gaining wider market coverage for a product, increasing access to group purchasing contracts and international markets, and developing possible synergy between product offerings.

The next MD&M Show and Conference will be held June 1—4 in New York. For information on this show, contact the Trade Show Division of Canon Communications llc at 310/392-5509.


Laser Microprocessing Company Opens

Services and laser systems offered

PhotoMachining Inc. has begun operations with facilities in Pelham, NH, and Menlo Park, CA. The company provides materials-processing services and turnkey laser systems.

The business partners include the company's CEO, Ronald Schaeffer, who has been in the laser industry for 15 years; the president, John O'Connell, who has over 15 years of experience at Spectra Physics, Laser Photonics, and Resonetics; Michael Welcome, an entrepeneur and owner of Precision Coatings Inc.; and Pat Sweeney, a retired CEO of HADCO and board member of HADCO and Manufacturing Services.

The company says that its task is to demystify lasers and allow their use in many manufacturing environments to produce small and high-quality features at competitive prices. The company's Windows-based software platform provides ease of use with standard excimer, sealed CO2, and solid-state lasers. It has the ability to easily control multiple axes, galvanometers, and machine vision, and can allow the user to download many file types compatible with drawing standards. Expansion modules for automation or manufacturing line integration can be plugged in.

For more information, call Photo-Machining at 603/882-9944.


Conference to Discuss the Medical Devices Directive

Will feature speakers from FDA and other regulatory agencies

Industry and government compliance authorities will be reporting on the newest laws, standards, and major future trends, at the CE Mark for Medical Devices Conference, "MDD '98," which is to be held May 5 in Washington, DC.

The European Union's Medical Devices Directive (MDD) becomes effective June 29 of this year, requiring all medical devices exported to Europe to have the CE mark. As part of the EU's new conformity assessment procedure under the MDD, manufacturers will have to have devices certified by a notified body. All aspects of the new directive, including strategies for compliance, will be covered at the conference.

The program will feature presentations by representatives from the LCIE (Central Laboratory for the Electric Industry) in France, the medical device manufacturing industry, U.S. and European testing labs, notified bodies, FDA and other regulatory agencies. Topics to be covered include European law on medical devices, the conformity assessment process, classification, clinical evaluations, production and product quality assurance systems, and other international standards that manufacturers must know.

For more information, call 800/839-1649.


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Compact Valves Help Miniaturize Device

MPMN Profile

Compact Valves Help Miniaturize Device

The evolution of medical devices is toward including more functions and upgrades while reducing overall weight and size. Arrow International (Everett, MA), which has specialized in the development and manufacture of intra-aortic balloons (IAB) and intra-aortic balloon pumps (IABP) since 1969, had a successful product on the market with their KAAT II Plus IABP. Nevertheless, Arrow engineers knew that in order to stay ahead of the competition, they would have to continually improve the design of the device.

The Smaller the Better

A model of compactness, the KAAT II Plus has no exposed parts. All of its connections are recessed and are accessible from one side of the pneumatic pump. The system includes either a lightweight 500-psi helium canister that provides a minimum of 21 days of continuous pumping or a refillable 2000-psi D-size cylinder that provides an extended helium supply.

Microprocessor controls and a stepper motor/bellows drive system deliver gas shuttle speeds for one-to-one pumping, even in patients with high heart rates and tachyarrhythmias. Accuracy of the delivered volume and the ability to set volume in 0.5-cm3 increments ensure patient safety and maximum effectiveness of the IABP assist.

In addition, all operating parameters are preset on system start-up, and most pump functions are already calibrated so that the IABP starts pumping at full volume within a few seconds of turning it on. An automatic purge at start-up means counterpulsation begins in less than one minute.

Seven distinct trigger modes provide maximum flexibility and the capability to pump in any situation. Either conventional timing or real-time R-wave deflation trigger/timing meets any clinical situation. The instrument continuously monitors balloon volume, pressure, and all operating systems. Should an alarm sound, the pump indicates which alarm is involved. A step-by-step troubleshooting procedure is also displayed. If a helium leak is detected, the pump automatically shuts down and prints the last 6 seconds of wave forms.

Where to Next?

The KAAT II Plus found immediate acceptance in the industry. Nevertheless, Arrow's engineering team had their eyes on the future. The Arrow team felt that the product could be further refined--particularly the large manifold and solenoid valve system. So in early 1993, the engineering team was already thinking about redesigning the IABP.

It was then that Dick Graeb, director of sales and marketing at Aerodyne Controls Corp. (Ronkonkoma, NY), made initial contact with Arrow International. Aerodyne designs and manufactures custom pneumatic valves and pressure regulators, solenoid valves, manifolds, assemblies, centrifuges, and nonmercury motion switches. Already well represented in the military and aerospace markets, this custom manufacturer was determined to break into the medical market.

Aerodyne's first opportunity came when Arrow contracted them for the redesign of one of the accessories of the KAAT II Plus: the check valve between the IABP's small and large helium canisters. The result was an extremely light (1.2 lb) component able to handle 2000 psi. The new valve did more than meet the required specifications; it gave Arrow the confidence to work with Aerodyne on the greater project of miniaturizing the IABP's manifold/solenoid assembly.

Heading up Arrow's team of engineers was project manager Mike Jesi. Aerodyne's design team was led by president Jim Miller and vice president of engineering Len Tetrault, both of whom were involved in the daily management of the new assembly's development.

Cross-Over Experience Counts

Was Aerodyne's military background a concern? "On the contrary," says Jesi. "First of all, they had a solid understanding of pneumatic controls. Secondly, they were accustomed to the rigors of documentation, compliance, and confidentiality."

Aerodyne's Tetrault says, "Often it's our experience in the application of our products that customers find valuable. The engineers at Arrow were about to develop this assembly in-house, yet they allowed us to do it, having seen just how significantly we were able to reduce not only volume and weight, but also noise and power requirements in other applications.

"A further consideration," Tetrault continues, "is concurrent engineering--in which design, manufacturing, assembly, and quality assurance specialists provide input from the beginning of the project. This process allows us, in almost every case, to increase production efficiency."

After approximately one year the Arrow team came to Ronkonkoma to witness the testing, which was a fairly complicated process. The test setup used an actual KAAT II Plus to ensure the assembly performed to specs. Not only did the assembly have to perform all mechanical and electrical functions properly, but it also had to respond correctly to the extremely sophisticated software commands on which the timing and safety features of the apparatus depends. Fortunately, the Arrow team was very pleased, and no significant modifications were required.

And the Beat Goes On

The result of this collaboration is a new IABP manifold/solenoid assembly that sits comfortably in the palm of the hand. Beyond miniaturization, one of the major benefits to the new assembly was enhanced reliability. Much of the plumbing (the pipes and fittings) was eliminated by manifolding, which in turn resulted in the elimination of potential leak points. A further result, and perhaps the most important, was reduced life cycle costs. The commitment to redesigning the pneumatics did represent an investment, but after virtually eliminating repair costs, service calls, and attendant downtime, the return on investment has been exceptionally fast and has reduced the number on the bottom line.

Arrow's new IABP is currently in the 510(k) process, and its introduction to the medical market is anticipated soon. With evolution in medical instrumentation having been served, a more compact and reliable IABP will soon be available.


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Spotlight on Valves

Spotlight
on Valves



Modular check valves

A company designs and manufactures an extensive family of check valves for a variety of applications. The valves provide accurate, reliable control of fluid or gas in low-pressure, low-flow systems. With over 16,000 possible configurations, these check valves offer a maximum degree of modularity and versatility. Clients can create their own custom valves from the company's stock parts by specifying cartridge size, end fitting (if applicable), cracking pressure, and materials. The valves are positive sealing, quick opening, and gamma and EtO sterilizable. Smart Products Inc., 1710 Ringwood Ave., San Jose, CA 95131.


Low-pressure valves

Plug valves are designed for fluid selection and redirection in low-pressure applications and are available in port sizes of 0.59 and 0.118 in. The wetted paths are made of chemically inert Teflon and Kel-F materials. Sixteen different flow, loop, and distribution valve configurations are offered. To allow for interchangeability of fittings, adapters, and tubing, the valve connections are via 1/4-28 UNF-2B fittings. Valves can be used freestanding or they can be mounted into panels for custom installation into control panels or instruments. Hamilton Co., P.O. Box 10030, Reno, NV 89520.


Split-stream valves

Low-pressure MicroSplitter valves offer a practical and economical way to meter a split stream at pressures up to 800 psi. These totally nonmetallic, biocompatible PEEK valves are available with 1/ 4-28 fittings for 1/16- and 1/8-in.-OD tubing, or 10-32 fittings for 1/16- in.-OD tubing, including a 10-32 with a 6-32 split-stream port for capillary tubing. The metering needle in these valves accurately reduces the split flow down to as low as 2 µl/min. Upchurch Scientific, 619 W. Oak St., Oak Harbor, WA 98277.


High-flow check valves

Clear one-way check valves of unique design offer unimpeded fluid flow, low opening pressure, and no backflow even at very low back pressures. Proprietary design of the one-way flow element allows this check valve to have a much greater flow rate than duckbill, ball-check, or disk-type valves. The valves are made from medical-grade plastic and silicone materials that can be EtO or gamma sterilized. Steam autoclavable valves are available on special request. Resenex Corp., 9614-F Cozycroft Ave., Chatsworth, CA 91311.


Panel-mount valves

Panel-mount isolation valves provide an economical solution for applications that require client access to port connections. The design isolates the valve solenoid from the port connections, thus isolating the instrument's electronics from the effects of accidental exposure to the working fluids. This design introduces a drip lip to divert potential fitting leakage away from the instrument panel. The incorporation of in-line porting assures user-friendly connections while guarding the integrity of instrument electronics. NResearch Inc., 267 Fairfield Ave., West Caldwell, NJ 07006.


Two-way solenoid valves

Two-way solenoid valves offer flows up to 50% greater than the manufacturer's standard Series 6 valves. The two-way valves with 3/8-in. NPT ports and 3/8-in. orifice size provide flow capability with a Cv factor of 0.90. The standard two-way solenoid valve is designed for applications with a maximum operating pressure differential of 5 psi. These customized units can also be modified to meet higher pressures. They are compatible with air or liquid media. KIP Inc., 72 Spring Ln., Farmington, CT 06034.


Three-way valves

Three-way chemically inert solenoid valves feature small size, fast response, and low power consumption, making them suitable for use in demanding clinical and analytical instrument applications. Each valve is 100% tested and inspected to ensure reliable long-term performance. The LFR-series valves are available in 12- and 24-V-dc models, and a variety of porting options and mounting styles. The Lee Co., P.O. Box 424, Westbrook, CT 06498.


Solenoid-operated pinch valves

For both moving fluids and gases, a line of pinch valves provides an easily controlled, contamination-free flow path. Pinch valves are well suited to irrigation or aspiration systems because tubing can be installed and removed easily without the need for difficult and unreliable cleaning methods. The valves are available in sizes as small as 17/8 in. in length and as light as 2 oz. They draw as little as 0.10 A at 24 V dc and are available in 12 V dc as well. They can handle from 21 in./Hg vacuum to 25 psi. Bio-Chem Valve Inc., 85 Fulton St., Boonton, NJ 07005.


Inert isolation valve

A two-way, normally closed, solenoid-operated valve features only two inert materials contacting the flow path. The body is made of Ultem polyetherimide, a polymer that performs well at high temperature, is biocompatible and FDA approved, and is applicable in numerous biomedical and biomechanical applications. The diaphragm that isolates the fluid path from the solenoid is made of ethylene propylene, also an inert material. Liquid flow rates up to 1.7 L/min at 2-psi differential are common. The valve is rated as bubbletight against 50 psi in either direction, and the barbed ports are configured to accommodate 1/4-in.-ID tubing. South Bend Controls Inc., 1237 Northside Blvd., South Bend, IN 46615.


Check valves

A manufacturer of disposable medical devices offers a full line of check valves in a variety of design configurations. Its product line includes in-line, normally closed, low-pressure one-way, TRAC, aspiration, and dual check valves. Available in a variety of flow rates, materials, sizes, and custom designs, the valves are designed to meet the toughest application challenges. Burron OEM Div., B. Braun Medical Inc., P.O. Box 4027, Bethlehem, PA 18018.


Disposable needleless valves

Needleless valves limit the risk of infection to health-care providers by replacing the hypodermic needle ports. A company's needleless line consists of a variety of low-priming-volume disposable parts including slip luer valves, Y ports, T ports, 1/4-in. tubing valves, and ANSI standard valves. These components are available in a variety of sterilizable materials. Halkey-Roberts Corp., 11600 9th St. N., St. Petersburg, FL 33716.


Plastic needle valves

A series of needle valves is suitable for instrumentation applications. The fine angle of the needle allows for the precise control of flow, which is restricted in both directions. The needle valves are adjustable from zero to the equivalent flow of a 0.025-in. orifice and can be provided for in-line installation or panel mounting. Two models are available: a standard glass-filled nylon model that is available with straight ports for 1/16-in.-ID tubing or barbs for 1/16- and 1/8-in.-ID tubing; and a new glass-filled polypropylene model that is suitable for those applications where chemical resistance is a concern. It is available with straight ports for 1/16-in.-ID tubing. Air Logic, 5102 Douglas Ave., Racine, WI 53402.

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Capacitor Plays Key Role in Maintaining Reliable Communication in Cancer Therapy System

MPMN Casebook

Capacitor Plays Key Role in Maintaining Reliable Communication in Cancer Therapy System

Decoupling unit met requirement for electronic noise suppression

When Therakos, a Johnson & Johnson Co. (Exton, PA), was developing its UVAR photopheresis system for the treatment of cutaneous T-cell lymphoma (CTCL), design engineers sought a highly reliable decoupling capacitor to provide electronic noise suppression.

The phototherapy system harnesses ultraviolet light with a pharmaceutical agent to alter the DNA of cancer cells and control the replication of abnormal blood cells. It maximizes toxicity to the target cells while minimizing the toxic effect to the patient since the photoactivation occurs outside the bloodstream. The UVAR system processes the patient's blood through a portable unit, cycling white cells and plasma through a Photoceptor chamber and then back to the patient. A PAC-1 memory chip in the Photoceptor plays a vital role in identifying the disposable chamber and guarding against cross-contamination of infectious disease.

To ensure error-free communication between the UVAR system and the Photoceptor unit, design engineers selected a Micro/Q 1000 flat decoupling capacitor manufactured by Circuit Components Inc. (Tempe, AZ) to decouple the memory chip. The Micro/Q 1000 capacitor, designed for through-hole mounting under dual in-line packages, is available in a variety of standard pin-outs as well as custom designs. This patented mounting configuration saves valuable printed circuit board space and enables the Micro/Q 1000 to provide a very low-impedance, low-inductance loop compared with conventional two-pin discrete capacitors.

"Because the Micro/Q 1000 shares plated through-holes with the PAC-1 memory chip, it allowed us to obtain effective decoupling in this part of the system," says Dennis Briggs, senior research engineer at Therakos. The capacitor "provided a direct fit" for Therakos's requirements.

In clinical trials, the UVAR photopheresis system has proved effective in altering the course of CTCL in patients who had failed to respond to other therapies. Moreover, the treatment produced none of the side effects associated with classic chemotherapy, because the photoactivation occurs outside the patient's bloodstream. The Micro/Q 1000 capacitor's role in decoupling the PAC-1 memory chip contributed to the system's success.


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