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Semiconductors: The Heart of Next-Generation Medical Devices
Highly integrated chips are paving the way for smaller, more portable equipment
Patrick O'Doherty, Analog Devices Inc. -- Design News, May 18, 2009
Cutting-edge technology, developed by semiconductor companies, is enabling the design of medical devices that improve the care of millions of people around the world. Soaring health care costs, the prevalence of obesity and chronic diseases, and a dramatic increase in the elderly population are creating a growing demand for affordable and reliable medical devices, including those for patient monitoring, medical imaging and instrumentation. Today, more than any other time in modern history, the semiconductor industry is paving the way for the advancement of medical devices that are saving countless lives and greatly reducing health care costs.
The large medical devices of yesterday have been redesigned as the portable units of today, some of which are now the size of a cell phone or even smaller. Some medical devices, such as ultrasound systems, which were once available only in hospitals and large urban medical clinics, are now commonly used in rural doctors' offices and ambulances. As the miniaturization and portability of medical equipment occurs, semiconductor manufacturers are challenged to develop highly integrated chips that will provide the enabling technology for next-generation medical devices, including increasingly lighter and smaller portable systems.
Patient Monitoring Systems
Patient monitoring equipment enables the continuous observation of critically ill patients, regardless of their location within the hospital, and often at a lower cost than using traditional bedside systems. Patient monitoring involves electrocardiogram (EKG), blood pressure, temperature, oxygen-saturation, respiration and, sometimes, automated external defibrillator (AED) functions that typically contain high-resolution analog-to-digital converters (ADCs), low-noise amplifiers, instrumentation amps and the combination of analog functions that have been around for many years. These are mature, high-performance systems in which major semiconductor manufacturers have invested a great deal of research dollars to develop innovative chips.
While these systems used to reside on the bedside, they are now becoming small enough to be hooked onto a person's belt. In the near future, EKGs, blood pressure and activity monitors will be combined with wireless communication functions that allow patients to be in their homes and still get safe and reliable vital-sign monitoring in real time. This will, in essence, lower the total cost of care.
The need for home-based patient monitoring devices is expanding due to the increasing number of aging baby boomers who require intensive home care. According to the World Health Organization, the worldwide number of persons aged 60 and older was 650 million in 2006. This figure is expected to reach 1.2 billion by 2025. In the U.S., people 65 and older now comprise a greater share of the population than ever before and this number is expected to steadily increase during the 21st Century.
“Due to an increasingly aging population, the health care sector is facing soaring costs for the care of chronically ill patients,” says Paul Errico, worldwide strategic marketing manager for Analog Devices' Healthcare Segment Team. “Today's medical devices, designed for home use, can monitor blood pressure, glucose levels and heart rates, and alert doctors to problems. This eliminates or reduces the need for costly office and hospital visits, and provides big benefits for patients who don't live near a doctor or hospital.”
To become a main factor in the way health care is managed, patient monitoring systems must be fully interoperable with one another and with other needed sources of patient information. While broad interoperability has not yet been achieved, it is a priority for the medical and information technology industries. The Continua Health Alliance, for example, is an organization working with technology, medical device and health care industry leaders to establish a system of interoperable solutions.
Medical Imaging
The use of medical imaging equipment, including CT (computed tomography) scanners and ultrasound systems, continues to grow as technology improvements render clearer, more detailed pictures of the human body for physician analysis and diagnosis. The medical imaging arena has seen a dramatic rise in channel counts-per-system and a commensurate focus by semiconductor companies on integration, low power and reducing cost-per-channel. Ultrasound, CT, magnetic resonance imaging (MRI) and positron emission tomography (PET), are all high-performance systems pushing standard components in terms of power, speed, accuracy and dynamic range.
A few years ago, portable ultrasound systems resembled a notebook PC. Today, ultrasound systems are using PDA or cell phone form factors and are small enough for doctors to carry in their pockets and use at will. This is greatly changing the use of ultrasound technology in terms of patient care. Needless to say, the power and footprint requirements for portable ultrasound systems are also dramatically different for today's systems.
“Medical equipment designers are being called upon to deliver high image quality and reliable performance without compromising power efficiency in devices that are sometimes scarcely larger than a human hand,” says Scott Pavlik, worldwide strategic marketing manager for Analog Devices' Healthcare Segment Team. “To do so, designers are capitalizing on significant improvements in underlying technologies, particularly in semiconductor component integration. IC ultrasound innovations are not only easing designers' tasks, but are also enabling significant advancements in the performance, size and power of ultrasound equipment — yielding greater product possibilities and expanded market opportunities.”
There are four major components that comprise an ultrasound system: low-noise amplifier (LNA), variable gain amplifier (VGA), anti-aliasing filter (AAF) and a high-speed analog-to-digital converter (ADC). In 2007, the first integrated analog front end ultrasound chip was announced by Analog Devices. The AD9271 replaced previous discrete solutions with a single integrated circuit that combined eight channels, each comprising an LNA, VGA, AAF and a 12-bit ADC. This unprecedented level of integration enables medical equipment designers to reduce the size of the signal path for mobile ultrasound systems by 50 percent and lower power requirements by 25 percent, all while achieving noise levels and other performance metrics required in critical care settings.
Integration is not the only key element that must be achieved in the design of today's portable ultrasound systems. The system also needs to be flexible and be able to adjust to the needs of various types of ultrasound probes, as well as provide ease-of-use in terms of programmable gain, filter cut-offs and system termination. It isn't enough for semiconductor manufacturers to define these very sophisticated parts and hand them out to customers with samples, evaluation boards and data sheets. Software tools that allow these products to be easily evaluated are also needed. All of this is evidence that semiconductor manufacturers are moving closer to the system designer's world.
It is estimated more than 62 million CT scans are done annually in the U.S. CT imaging combines special X-ray equipment with sophisticated computers to produce internal 2-D and 3-D images of the human body to diagnose problems that include cancer, cardiovascular disease and musculoskeletal disorders. In a CT system, large numbers of data acquisition channels are arranged in slices. Higher slice counts are what makes CT scanners able to more quickly provide detailed images, while exposing patients to a lower X-ray dose.
Current and next-generation CT scanners require a massive channel-count increase, but the system size and cost cannot grow at the same rate as the channel count. The analog front end, the most complex part of the system, is critical to the system's performance. Thus, to enable massive channel counts, semiconductor designers must look at ways to integrate higher functionality while lowering power consumption and cost.
The partnership between semiconductor designers and system designers is absolutely critical in the CT space. During the past several years, there has been a tremendous amount of innovation and progress in CT development and a great deal more is expected to occur in the coming years. Analog Devices, for example, recently introduced a new medical imaging chip that enables high slice-count CT systems to capture real-time moving images — such as a beating heart — with a high degree of accuracy and detail. The ADAS1128 offers 128 data conversion channels and enables diagnostic system designers to develop CT scanners that produce clearer images of internal organs and bones while reducing radiation exposure compared with older machines. This is invaluable in critical care areas, such as cardiology, neurology and angiography.
Medical Instrumentation
This segment of the medical device market includes blood analysis, blood pressure meters, infusion pumps and dialysis machines, as well as a wide variety of other in vitro functions.
One example of using cutting-edge semiconductor technology in an otherwise very mature measurement system is the use of tri-axis accelerometer technology in blood pressure meters. The most common way to get an inaccurate blood pressure reading is to have your arm at the wrong level relative to your heart. Using a tri-axis accelerometer (identical to that used in current computer games) to measure the tilt of your arm helps ensure the blood pressure reading is accurate.
A typical way to analyze blood for diagnosing medical conditions is to examine its DNA characteristics. When a virus is present, the DNA characteristics of the blood typically change and so does the impedance of the sample in complex form. By mapping virus strings to those impedance profiles, medical professionals can identify and detect viruses in the blood. System designers are being asked to design spectrum analyzers into handheld meters, but cannot accomplish the task with available discrete devices. So, they must work with the semiconductor industry to see if this function can be integrated onto a single chip as is currently available in recent impedance metering analog front ends.
Semiconductors can generally do what is needed to enable high-performance systems. The real key is to achieve the required performance while keeping within an aggressive system power budget, footprint requirement and being able to provide other high value functions that can be combined onto one piece of silicon to provide the greatest benefit to the system. It is this applications' knowledge that semiconductor companies are constantly striving to develop. In this respect, our customers are our teachers and the end result is that semiconductor companies, system manufacturers and, most importantly, patients benefit from effective communication between the major technology stakeholders.
Medical design engineers creating the latest health care systems aimed at disease management, health and wellness, and drug delivery are using semiconductors as the foundation to invent next-generation products that change lives. Communication between medical system and semiconductor designers is vital because the more semiconductor companies learn about what medical equipment designers need, the more everyone around the world who may need medical care will benefit.
Analog Devices' ADAS1128: http://designnews.hotims.com/23104-500
Analog Devices' AD9271: http://designnews.hotims.com/23104-501
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Semiconductors: The Heart of Next-Generation Medical Devices
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Erich Specht - 2009-10-7 15:00:30 EDT
