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Driving Design Excellence With Test

Thu, 05/08/2008 - 8:40am

Effective data collection methods and quality test systems are critical elements in ensuring medical device design success. Specifically focusing on medical electronic devices, this article will review how significant these two aspects can be throughout various stages of product development and delivery to market.

By Chris Rehl

As medical electronic devices (MEDs) continue to evolve each day, the critical part they play in enhancing overall patient care, improving the quality of life, and saving the lives of thousands is no secret.

MEDs encompass a growing range of products. They include patient-focused devices such as pacemakers, defibrillators, and implanted devices, as well as those that tend not to demand the spotlight, such as MRI scanners and patient monitoring equipment. Robots for rehabilitation and embedded communications devices are among the most recent developments. All share one common thread-products that can produce the highest level of diagnostic confidence and optimal patient care for millions across the globe.

By their nature, MEDs have enabled trained technicians, physicians, and biotechnologists to not only improve life expectancies, but also provide important data for groundbreaking research and analysis in areas such as brain mapping and the genome project.
Functionality and Reliability

Not only has the number of MEDs changed significantly today, but so has the way they are designed. Medical device manufacturers are tasked with developing the most efficient product while facing a growing number of transitions-a push towards more sophisticated technology; the production of smaller, more compact products; changes in design ergonomics; a rise in combination products; added energy efficiency; and enhanced circuit designs.

One of the most prominent shifts today deals with a rapidly aging population. According to the World Health Organization, senior citizens at least 65 years of age will increase in number by 88% in the coming years. By 2050, the U.S.'s contingent of seniors is expected to double from 40 to 80 million.

It's clear the first wave of the baby boomer generation is just starting to make its effect obvious to the medical industry as a whole. As the bubble of people born in the early 1950s to the late 1960s reaches their mid 60s, the dependency on an increasing number of medical devices will become more commonplace.

As the usage numbers and benefits of MEDs increase, they will become even more life-critical. Reliability and operational excellence of MEDs are more imperative than ever before. Product failures and recalls are damaging-and potentially life-threatening-not only to the patients and caregivers who need them, but to the reputation and strength of the OEMs who produce the products. Any shortcoming can result in millions of lost dollars, potential lawsuits, and a drastic dip in brand loyalty.

Recent high-profile recalls of defibrillator products are just one example of the need to deliver reliable, high-quality devices to the public: These include:
  • An October 2007 Class 1 recall of Medtronic defibrillator leads after lead breaks resulted in inappropriate shocks or result in a loss of therapy.
  • A March 2007 voluntary recall of 42,000 Defibtech, LLC semi-automatic external defibrillators, where a potential low battery issue would result in the inability to deliver a defibrillation shock.
  • A 2005 Class 1 recall of 672 HeartSine Technologies' Defibrillators (AEDs) after several device shutdowns resulted in fear of an inability to deliver shock, delays in treatment of even possible injuries, or death.
  • A 2005 recall of a potential battery shorting in a subset of Medtronic implantable cardioverter-defibrillators.
  • A 2005 recall of more than nine models of pacemakers from Guidant Corp., resulting after several product failures from a seal leakage in several dozen devices.

As these instances illustrate, MEDs need to retain the highest level of long-term quality and reliability, which all starts in the design phase. Medical manufacturers must gain accurate visibility into component and supplier quality data throughout the entire manufacturing assembly process to build the best product possible.

However, this is a lot easier said than done. Market conditions-mainly a push towards outsourcing manufacturing operations-has placed serious strains on continuous quality improvements. The basic advantage of today's manufacturing outsourcing model has moved well beyond pure labor cost and cheaper access to components. Engagements are now being measured by the ability to simplify logistics and import duties to capitalize on growing regional consumer markets.

Outsourcing manufacturing operations also creates control and management issues around product quality. OEMs have an immense opportunity to address the recent public debate surrounding recalls and substandard products resulting from outsourced manufacturers by upping the ante on accountability and oversight. Yet, time after time, market speed and lower costs are the primary business initiatives-leaving even more major, potentially devastating, sacrifices to quality.
Starting With Better Product Design

Product design is an iterative process and can be viewed as a series of reasonable abstract assumptions, followed by the prototyping and measuring or testing of those initial assumptions. This approach can yield long term product quality increases throughout the entire lifecycle of products.

Robust test systems provide data for continual quality improvements for MEDs.


To account for product quality issues related to the design process, test and measurement steps must be performed and results must be incorporated as feedback into improvements to the initial design in phases. This process should be followed throughout the typical phases of concept, design, prototype production, and post-sales support.

The initial design phase typically uses a series of electronic design automation tools and processes to develop the conceptual design. CAD and PLM applications help design engineers create the initial conceptual design and capture all the pertinent assumption data. Component specification data is created or captured and added to libraries for use by simulation applications which test various parameters and tolerances of a conceptual design. During simulation, designs are tested against theoretical design rules and component behavior, and a variety of performance data is generated to identify obvious problems and performance improvements that can be fed back to the initial design approach.

Additionally, in the initial design phase, Design for Manufacturing and Design for Test methodologies should be used to allow products to flow through later phases of the product development cycles.

Once the initial design phase is completed, a limited number of physical prototypes are created and used to prove that the initial design is practical and can be realized. During this phase, it is common for the build and testing development team to use non-automated processes. Prototypes are typically put into a design validation test cycle, which applies a variety of input stimulus to the product and resulting behavior is recorded and measured against expected results. These can point out obvious or potential product shortcomings and be utilized to apply re-design or tweaks to improve performance.

The production phase of electronic devices holds the keys to bringing the original design concept to reality. A wide variety of data can be gathered and analyzed across multiple processes to identify controllable sources of variance that eliminate waste and improve production yields and product quality.

Functional test ensure product design features and capablities remain in place as a product is delivered to market.


This includes:
  • Gathering component quality data obtained from component manufacturers, ensuring that key performance and margin specifications are verified before the production process begins, minimizing the risk of time- and cost-consuming re-dos.
  • Manufacturing test steps including automated optical inspection (AOI), X-ray, and in-circuit testing (ICT), where data can be gathered and analyzed to point out process and mechanical design issues early on.
  • Functional test, which is typically performed after a series of assembly steps to ensure proper operation of sub-assemblies before moving to subsequent assembly steps. Data generated here can assess primary product quality and reliability by analyzing key product parameters including anything from pass/fail to advanced parametric data.
  • Final system testing can be performed to verify that the products designed are built and operated the way that is intended.

Post-sales support and repair center operations generate valuable data that can be analyzed to enhance the efficiency of customer interactions, increase repair operations, and provide a complete product genealogy linked back to the initial design phase. Data gathered in this stage of a product lifecycle includes reported behavioral problems, component failure usage information, and other field exposure results.
Maintaining the Competitive Edge

With the ability to access, organize, and analyze test and quality data generated by production lifecycles quickly and efficiently, medical designers can stay ahead of their competition, while increasing operational efficiencies and minimizing risk.

Despite this massive opportunity-coupled with the fact that effective access to test data often represents the largest opportunity for significant improvements in design concepts development, product performance, and increased reliability-many organizations have no coherent access to that data. Large amounts of time and resources are spent developing custom solutions which are obsolete before even being deployed, as the data landscape is subject to frequently changing business and product demands.

Data collection and analysis should be implemented across the entire production lifecycle for medical electronic products. The key to this lies with gathering component quality data from the end-to-end production process, using it for correlations and optimizations to the original product design. Pertinent data that must be on any organizations radar includes:
  • Inbound component quality can be proactively managed by gathering component and subassembly test and quality data from external suppliers. This enables both preventative action before a product is built with sub-standard components, and also provides end-to-end correlation with the manufacturing and return material modules for closed-loop quality improvements
  • Production test and process data from electronics manufacturers provides deep insight into gaining better yields, unit genealogy, inventories, lot histories, and test station management. The ability to monitor or enforce process and test steps, combined with statistical process control, means that quality variations can be tightly controlled.
  • Repair process data contributes to product quality increases by correlating product failures with the entire product genealogy and history of each product-component quality data, test results, process steps, and rework history.
Conclusion

Finding the right data collection and analysis system provides the best way to realize these benefits and effectively manage MED products from design through the customer usage cycles of a product line. The ability to create complete product genealogies and full traceability of component quality, test, process data, and post sales data down to an individual serial number or product family is invaluable information that can be used by design engineers to radically improve product reliability and quality.

The design process can be improved through a variety of means using test data collection and analysis, including design verification, variance profiling, and failure analysis among other correlation and optimization steps. Through real-time data collection and analysis, design engineers can see if products are being built as designed-within acceptable margins and tolerances-and make rapid adjustments to the original designs.

The ability to collect a wide variety of data types-and turn them into actionable insight-not only tears down the wall between design and implementation of devices, but also opens the floodgates to continual process improvements, innovation, and more intelligent answers to today's biggest medical challenges.
Online

For additional information on the technologies and products discussed in this article, see MDT online at www.mdtmag.com or CIMTEK at www.cimtek.com.

Chris Rehl is the director of marketing at CIMTEK. He can be reached at 781-726-6227 or crehl@cimtek.com
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