Smaller Diagnostics and Changes in Materials Drive Medical Market

Imagine a new kind of electrocardiogram (ECG) without thetypical jumble of crisscrossed wires, gels and electrodes. Instead of all that,this new-age ECG would use an adhesive patch, about the size of a Band-Aid, toextract performance data from the heart. It might also measure respiration,blood pressure and body temperature, and then store all that data in memory fordays before being disposed of.

Sound too good to be true?Maybe so, but many such devices are already reaching the prototype stage, andcould hit the market as soon as the next 12 to 18 months. The key is thedevelopment of a new breed of electronic components that dramatically reducesize and current consumption.

"These very small form factorshave enabled creation of new products that could never have existed in thepast," says Robert Burnham, marketing manager for biopotential analog front ends at Texas Instruments. "To create such feature-richproducts in the past, the electronics would have been too big and the batterylife would have been too short."

Indeed, one of the keys tothis diagnostic revolution is the development of analog front ends (AFEs) thatpack dozens of discrete components - amplifiers, filters, attenuators andconverters - into electronic packages measuring less than 10 mm on a side.Component suppliers Texas Instruments and Analog Devices have both announced AFEs thatincorporate ECG and respiration monitoring capabilities onboard. In April,Texas Instruments rolled out a chip with ECG, EEG (electroencephalograph) andrespiration impedance measurement. Measuring 8 x 8 mm, the 24-bit ADS1298Rdevice packs 40 analog components and is said to be 97 percent smaller and use95 percent less power than discrete implementations.

Similarly, Analog Devicesannounced in February that it is introducing the ADAS1000ECG analog front end, which incorporates pacemaker pulse detection andrespiration measurement. The new device, which incorporates 50 analog parts,reduces a conventional 4 x 6 inch printed circuit board down to a singlesilicon chip.

Such parts enable the construction of smaller diagnostic systemsfor two reasons: first, the chips themselves are vastly smaller than theirpredecessors; second, the AFEs enable engineers to use much smaller batteries.

"Our device, at only 750 µWper channel, uses only about 6 mW in an eight-channel part," Burnham says. "Itreally moves the bar for portable devices." Burnham says that with the newbreed of analog front ends, many applications will be able to replace AAA or AAbatteries with so-called "button cell" batteries.

Analog Devices engineers saytheir AFEs will be able to record electrical activity of a heart in detail,enabling accurate analysis of numerous heart conditions, ranging from birthdefects to arrhythmias to lack of blood flow. While all of those capabilitiesare commonplace today, they are generally done by cart-based instruments.

But by combining the new AFEswith a small processor, a memory device and a tiny battery, engineers say theycan bring the size of an ECG monitor down to an adhesive patch measuring just 3x ¾ x ¼ inch.

"Tiny is what people are looking for, saysPatrick O'Doherty, vice president of the Healthcare Segment for Analog Devices."This technology will be clipped on people's belts and go inside Band-Aids."

Many engineers say the obviousfirst step for the technology is to serve as a decidedly smaller replacement tothe well-known Holtermonitor, an ECG device that is strapped onto patients for days at a time tocheck their hearts for abnormalities. In those applications, the new AFEs couldoffer a significant cost advantage. Because the new devices could potentiallybe disposable, they would eliminate the cost associated with collecting data,cleaning and re-packaging the monitor each time it's used by another patient.Those steps are now said to cost between $27 and $44.

"So the threshold for adisposable monitor doesn't have to be $1 or $2; it just needs to be less than$27," Burnham says. "That's not tough to achieve."

Some medical suppliers arealready building medical products that use variations of the new technology. Imec, a Belgium-basednanoelectronics company, has already built a smart ECGnecklace that can be worn around a person's neck like an ID badge. Thesmart ECG necklace, which works with two electrodes attached to the body, embedsa beat detection algorithm and is already being employed for ambulatory cardiacmonitoring.

The Holy Grail, however, is still the creation of ECG systems ina small stickable bandage. By rolling the AFE chips together with a wirelesstransceiver and four or five small electrodes inside the bandage, engineerscould eliminate the jumble of crisscrossed wires that's normally associatedwith ECGs.

"People who get an electrocardiogram won'tneed to be wrapped up in leads anymore," O'Doherty says.

If the technology receiveswidespread adoption, it could also open the door to a multitude of otherpossibilities. Temperatures, blood pressure measurements and respiration, alongwith ECGs, could all be done by a stickable bandage.

"I know many customers who arewell along in their approval process," Burnham says. "Those products aredefinitely on their way."

Health Reform Drives Material Changes

Just as newtechnologies are changing the way designers develop products for the medicalindustry, so too are regulations - particularly in the area of materialsselection.

Industry experts interviewed by Design News see these specific trends in materials' selection:

"The health care industry isin a period of dramatic change due to urgent calls for quality improvements andcost reduction," says Thomas O'Brien, global product marketing director, healthcare, Sabic Innovative Plastics. "Medical device manufacturers are right in themiddle of this process and are looking for answers from suppliers - includingnew ways to design and manufacture to achieve the highest quality, meet newregulatory requirements, support new care approaches and drive down costs."

Fighting infections inhospitals may be the top immediate priority. In 2009, Medicare said it would nolonger pay hospitals for additional costs to treat hospital-acquiredinfections. As a result, hospitals are declaring an all-out war on germs.

Two major producers of transparentplastics are rolling out new tougher grades.

"We understand that thismarket is changing," says Carmen Rodriguez, business manager, resin products atAltuglas International Resin, part of the Arkema group. "New developmentsdictate that we take a different approach."

Altuglas International has developed what it describes as thenext generation of impact acrylic polymers for use in transparent disposablemedical devices. They are said to offer improved resistance to environmentalstress cracking (ESC), excellent gamma sterilization resistance and good meltprocessability. Target applications include drug delivery applications asinfusion systems, stopcocks, manifolds, luers, and intravenous (IV) and syringecomponents. 

Arkema says the polymers' superior resistance to isopropylalcohol (IPA) is particularly important because of patient safety guidelinesaimed at preventing catheter-related blood stream infections that require newdisinfecting techniques. One of those techniques is rigorous cleaning ofintravenous lines.

Evonik Cyro is now marketing an acrylic-based multipolymercompound that uses a proprietary silver-based antimicrobial agent to kill germson the surface of medical equipment. The compound targets FDA-regulated Class Ior Class II medical devices covered by 501(k) submission. Evonik Cyro expectsthe materials to be used in place of existing acrylic compounds, polycarbonateor polyvinyl chloride (PVC).

George Pape, head of medical and pharma in North America for the Clariant Masterbatch Business, says he also sees renewed interest inantimicrobial compounds for medical applications. "Everything is pretty muchdone on a custom basis," says Pape. Some applications require maximum protection, and others may be less critical. He sees a trend in particular to the silver-based antimicrobials.

Efficiency is also an important trend affecting materialsselection in the medical market.

"More efficient use of operating room resources requires quickvisual confirmation and improved inventory tracking and management" says JudyMelville, industry manager at Solvay Advanced Plastics.

One method for quick visual confirmation is using colors todistinguish different medical instruments or components. That can be tricky formedical applications because many plastics are colored with dyes, which canmigrate to the surface of molded products.

Clariant is introducing Mevopur color concentrates and pre-colorcompounds, whose ingredients have been biologically evaluated against USP parts87 and 88 (Class VI devices). Clariant also recently launched a new range ofglobally harmonized standard colors for polypropylene and polyethylene, as wellas other materials such as polyether block amide plastic, where ingredientshave been biologically evaluated according to ISO10993 and USP parts 87 and 88(Class VI).

Wavemark Inc. is putting radio frequency identification (RFID)tags on the packages of expensive medical devices to monitor inventories ofsuch items. The company estimates that supply chain expenses as a percentage ofcost of goods is 39 percent for medical devices, compared to 3 to 6 percent forretail stores. 

One technology on display at MD&M West that has significantpotential to boost RFID use in medical devices is called 3D-MID. HartingMitronics is producing three-dimensional injection-molded RFID tags  based on 3D-MID (MID is an acronym for moldedinterconnect device). A laser activates the surface of a plastic part made withspecially engineered plastics. Then, the activated surface area is chemicallyplated to create the antenna. The process is called LPKF LDS (laser directstructuring).

Another megatrend in themedical market is at-home care. Moving patients out of the hospital, whenpossible, reduces costs and decreases risks of infection. Several exhibitors atMD&M West showed portable medical devices for home or field use that employlightweight plastics for housings and other components that previously havebeen made from metals.

One example is the Inogen One G2 System, a second-generation portableoxygen concentrator. Compared to its predecessor, it's 40 percent smaller, 25percent lighter, with 20 percent more oxygen and a longer battery life.

"Durability is one of the most critical factors of our device,"says John Stump, mechanical design engineer, Inogen. "We have experimented withmany different grades of resin to find the best quality molded parts for ourapplication."  The portable device'sshell is constructed of six separate components molded from BayerMaterialScience LLC's Bayblend FR 3010 polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) plastic. The external battery housingis also made of three components molded from the same polycarbonate blend.

Look for challenges on materials' technology to escalate as theeffort to improve health care and reduce costs intensifies.