Originally Published MPMN July/August 2007

SPECIAL FEATURE: IMPLANTABLES

It's What's Inside That Counts

Wireless systems, miniature devices, and widespread growth are ahead for electronic implantable devices

Shana Leonard

Patients outfitted with an implantable cardioverter-defibrillator (ICD) rely on the device to monitor heart rhythms and to deliver shocks to restore normalcy if rapid or abnormal rhythms are detected. Aside from patients actually feeling a defibrillation produced by the ICD (a telltale sign that the implant is working), there is little information available regarding battery life, implant health, and patient health without a visit to the doctor’s office for retrieval of the device’s stored data.

But what if this weren’t the case? Remote monitoring technology may someday allow a common device such as a cell phone to wirelessly receive data from an electronic implant and transmit it to a healthcare network. Implants could periodically send out data, updating healthcare professionals or networks as to implant and patient health, as well as alerting them to emergency situations—all without the need for a doctor’s appointment. The result could be improved quality of life and better healthcare for patients.

Remote monitoring is just one of many possibilities for the future of electronic implants. Along with the emergence of wireless telemetry systems, miniaturization and microelectromechanical systems (MEMS) technology are fueling change in the electronic implantable device industry. After all, OEMs are constantly striving to improve implantable device technology and design for the benefit of physicians and patients alike. And despite inherent risks associated with electronics, manufacturers are eagerly pushing progress of these implantable devices in revolutionary new directions.

Cutting the Cord

Remote monitoring may be in store for the future; but for now, small victories in implantable device development will have to suffice. Historically, electronic implant monitoring has required magnetic coupling of the device inside the patient to external equipment—a setup that has sometimes demanded contact with the body and uncomfortable positioning. Frustration with the method has been further exacerbated by data transfer processes that last as long as 15 minutes in some cases.

All that changed with the establishment of the Medical Implant Communications Service (MICS) in 1999. Galvanized by the desire to improve implants and patient care, Medtronic (Minneapolis; www.medtronic.com) petitioned the government for MICS and the Federal Communications Commission (FCC) established the service with some slight modifications.

FCC approved MICS as an “ultra-low-power unlicensed mobile radio service for transmitting data in support of the diagnostic and/or therapeutic functions associated with implanted medical devices.” Operating within the 402- to 405-MHz band, MICS allows for speedy transmission of data from electronic implants without interfering with other users of the spectrum. Wireless telemetry systems enable a data transfer range of roughly 2 m, consequently eliminating the need for body contact between the patient and the external transceiver.

In light of this development, Zarlink Semiconductor Inc. (Ottawa, ON, Canada; www.zarlink.com) developed what it maintains is the only transceiver specifically designed for MICS on the market. Capable of transmitting data at a rate of up to 800 Kb/sec, the ZL70101 medical implantable radio-frequency (RF) transceiver can operate wirelessly at a range greater than 2 m. It is also a low-power device that has a standby mode of no more than 250 nA. The product is suited for use with such implantable devices as pacemakers, ICDs, neurostimulators, insulin pumps, physiological monitors, and bladder control devices.

“With this type of wireless technology, patients don’t have to go to a particular doctor’s office for follow-up visits once they have an implanted device. They can use this wireless MICS-enabled device with a remote home-monitoring base station and have the peace of mind that their device is being monitored on a regular basis without any sort of patient intervention,” says Sahil Bansal, product marketing manager with Zarlink’s ultra-low-power communications group. “From an OEM perspective, the benefits are ease of use and ease of being able to monitor their device to check on things like whether the therapy is working and…the general health of the implanted device.”

Transceivers such as Zarlink’s are the first step toward a more advanced method of remote monitoring as envisioned with the cell phone scenario. But there is still a way to go until this is achieved since RF and wireless technologies are still relatively new to implantable medical devices. “A lot more people want telemetry in their implants when they’re going to communicate with RF,” says Jim Ohneck, director of sales and marketing for Valtronic USA Inc. (Solon, OH; www.valtronic.com), a company specializing in electronics manufacturing.

“But right now, the tools and techniques to use RF to communicate with the body aren’t that good; they’re very inefficient. So, we’re seeing a focus in the healthcare industry to try to improve methods to communicate back and forth with implants.”

Shrinking Devices

Remote monitoring isn’t the only electronics-enabled progress that industry insiders predict for the future. Someday, minuscule implantable biocomputers constructed from DNA, RNA, and proteins may navigate the hostile terrain inside our bodies hunting mutated genes, according to researchers from Harvard and Princeton universities. They maintain that such devices’ in vivo calculations could enable the development of biosensors designed to target specific types or groups of cells, leading to many potential applications. And to many researchers, this seemingly fantastical scenario represents a viable future reality.

Experts are painting a picture of a not-to-distant future in which micro- and nanosized electronic implants are introduced into the body via injection rather than surgery. Enabling a portion of this impending implant evolution are miniaturization and the rise of MEMS.

Diminution of devices has opened doors to a whole new realm of possibilities in the medical industry. Valtronic is one company to have capitalized off of its competence with electronics manufacturing, especially at the miniature level. Specializing in bare die, chip-on-board, flip-chip, and 3-D chip-scale applications—and, more recently, applications requiring folded circuit boards—has equipped the company to handle, as well as create, shrinking devices.

Valtronic has laid claim to manufacturing the world’s smallest canal hearing aid, which is so tiny that users can insert the implant completely in the ear canal and even take a shower while wearing it, according to Ohneck. Moreover, collaboration with two other companies produced the tiniest implantable pulse generator yet developed. The Micropulse, for which Valtronic minimized the circuitry, is suited for implants treating urinary incontinence, chronic pain, and limb dysfunction, and is expected to enter clinical trials this year.

Shrinking devices may promote new technologies and patient comfort, but is there such a thing as too small? Ohneck admits that there are limitations on just how small a device can go and laments that sometimes OEMs don’t always take manufacturability of designs into account when designing a device. “Yes, we can use technologies to make a circuit small enough that you can put it in the body with a syringe, but to put that through a channel of production which involves wafer manufacture and sometimes redistribution on the wafer and then packaging onto a flexible printed circuit board, you begin to create something that is very costly, not very practical, and very difficult to test,” he says. “I think sometimes people say they want to use the most advanced technology to make this thing as teeny tiny as possible, when if they made something a slight percent bigger, it would be a lot easier to manufacture and a lot more cost-effective.”

As OEMs continue to downsize devices, the buzzword bandied about is ‘MEMS.’ “The technology that MEMS offers is going to really revolutionize what a lot of these devices can do,” says Jesse Bonfeld, medical market segment manager for Endevco Corp. (San Juan Capistrano, CA; www.endevco.com). Among other products, the company manufactures a surface-mount variable-capacitance silicon MEMS-enabled accelerometer suited for such implants as cardiac pacemakers and defibrillators.

Bonfeld considers MEMS to be the key to creating high-performance long-term implants that can outlast current versions. But he’s not holding his breath for the MEMS-enabled miracles to commence just yet. Concealed beneath the optimism and hype surrounding this potential-laden technology exist quite a few question marks.

“The MEMS industry is fairly young and is not mature. The challenge for the MEMS industry is that it has a huge installed base, there’s a lot of overhead, and firms need a lot of volume to cover that overhead—and the medical industry doesn’t have that volume yet,” says Bonfeld. “MEMS providers [need to] migrate their technology and allocate their resources and their capacity toward looking at these higher value, higher price point, somewhat better margin [products], like implantable medical devices.”

Ohneck also acknowledges that actualization of MEMS concepts has prevented widespread adoption in the industry. “There’s been a lot of focus on the wafer level of MEMS, but there’s been very limited focus on how to use MEMS in the real world,” he says. People have not invested much thought on logistics, such as how a MEMS sensor is attached, according to Ohneck. And while he points out that this can be done through flip-chip processes, Ohneck cautions that a MEMS device must be designed by the OEM to connect with that type of packaging.

Additional considerations for MEMS-enabled implants are power sources. Prior to MEMS, implants incorporated piezoelectric technology in activity-monitoring devices. The advantage to piezoelectrics over MEMS is that a MEMS device needs to be powered, whereas a piezoelectric-powered device does not, according to Bonfeld. Moreover, opportunities may arise from piezoelectrics that could even provide energy regeneration, he says.

Taking Precautions

With MEMS capabilities and new technologies on the rise, possibilities for the electronic implantable device market seem limitless. Moreover, a massive aging population with a longer life span than its predecessors is sure to increase demand for more and better implantable devices. In light of these factors, the global market for microelectronic medical implants is projected to balloon to $32.2 billion by 2009, according to a report by the Business Communications Company, Inc.

But while the field remains lucrative, there are significant risks. Despite rigorous testing and extensive documentation, electronic implantable devices are fallible. Finite battery life presents a challenge and a concern. Meanwhile, malfunctioning components are always a looming threat that can end in a recall, which can be costly—in both money and reputation.

Recent recalls have rocked the electronic implant industry. In 2005, Guidant Corp. (St. Paul, MN; www.guidant.com) recalled several implantable defibrillator models due to such problems as potential internal short circuits, memory error, and component failure, and also recalled several pacemaker models owing to a seal that could leak. This past April, Guidant/Boston Scientific issued another recall affecting an estimated 73,000 ICDs and cardiac resynchronization therapy defibrillators, stemming from a potentially malfunctioning capacitor that could lead to premature battery depletion.

Most implantable devices are robust and devoid of problems; however, the recent recalls have shaken confidence and garnered negative publicity for the industry. Consequently, the industry is experiencing intensified scrutiny of quality, processes, and traceability, according to suppliers. “Every company comes in and does a quality audit here,” says Ohneck of Valtronic. “We’ve seen our customers ask tougher questions, give tougher quality audits, and be pickier about what they do.”

Bonfeld of Endevco has witnessed a heightened emphasis on component traceability, documentation, and failure analysis. FDA is cracking down and is aggressively forcing device manufacturers to reacquire devices from deceased patients or upon explantation from living ones, he says. The aim is to conduct failure analyses on the devices with the intent of helping predict longevity of the individual components.

“Device replacement protocol is usually dictated by the battery life, but there are all these other components in there and device manufacturers don’t have as much knowledge as they’d like to have, or that FDA wants them to have, about what the mean time between failures is for a capacitor, sensors, transducers, etc.,” Bonfeld says.

An emphasis on failure analysis and documentation provided by suppliers is likely to increase, as will pressure and surveillance from FDA. Yet despite the tremendous risk involved with electronic implants, manufacturers are eager to press forward with development because the benefits tend to greatly outweigh the risks. Though a risky business, implantable devices have proven profitable for both manufacturers and patients. Without the electronic components and circuitry that compose these devices, patients’ quality of life would be compromised by debilitating conditions. Instead, implantation of these complex devices helps keep tickers ticking, pain at bay, and numerous other sidelining problems under control.

Copyright ©2007 Medical Product Manufacturing News