Imagine a new kind of electrocardiogram (ECG) without the
typical 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, to
extract performance data from the heart. It might also measure respiration,
blood pressure and body temperature, and then store all that data in memory for
days before being disposed of.
Sound too good to be true?
Maybe so, but many such devices are already reaching the prototype stage, and
could hit the market as soon as the next 12 to 18 months. The key is the
development of a new breed of electronic components that dramatically reduce
size and current consumption.
"These very small form factors
have enabled creation of new products that could never have existed in the
past," says Robert Burnham, marketing manager for biopotential analog front ends at Texas Instruments. "To create such feature-rich
products in the past, the electronics would have been too big and the battery
life would have been too short."
Indeed, one of the keys to
this diagnostic revolution is the development of analog front ends (AFEs) that
pack dozens of discrete components - amplifiers, filters, attenuators and
converters - into electronic packages measuring less than 10 mm on a side.
Component suppliers
Texas Instruments and
Analog Devices have both announced AFEs that
incorporate ECG and respiration monitoring capabilities onboard. In April,
Texas Instruments rolled out a chip with ECG, EEG (electroencephalograph) and
respiration impedance measurement. Measuring 8 x 8 mm, the 24-bit ADS1298R
device packs 40 analog components and is said to be 97 percent smaller and use
95 percent less power than discrete implementations.
Similarly, Analog Devices
announced in February that it is introducing the
ADAS1000
ECG analog front end, which incorporates pacemaker pulse detection and
respiration measurement. The new device, which incorporates 50 analog parts,
reduces a conventional 4 x 6 inch printed circuit board down to a single
silicon chip.
Such parts enable the construction of smaller diagnostic systems
for two reasons: first, the chips themselves are vastly smaller than their
predecessors; second, the AFEs enable engineers to use much smaller batteries.
"Our device, at only 750 µW
per channel, uses only about 6 mW in an eight-channel part," Burnham says. "It
really moves the bar for portable devices." Burnham says that with the new
breed of analog front ends, many applications will be able to replace AAA or AA
batteries with so-called "button cell" batteries.
Analog Devices engineers say
their AFEs will be able to record electrical activity of a heart in detail,
enabling accurate analysis of numerous heart conditions, ranging from birth
defects to arrhythmias to lack of blood flow. While all of those capabilities
are commonplace today, they are generally done by cart-based instruments.
But by combining the new AFEs
with a small processor, a memory device and a tiny battery, engineers say they
can bring the size of an ECG monitor down to an adhesive patch measuring just 3
x ¾ x ¼ inch.
"Tiny is what people are looking for, says
Patrick 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 obvious
first step for the technology is to serve as a decidedly smaller replacement to
the well-known
Holter
monitor, an ECG device that is strapped onto patients for days at a time to
check their hearts for abnormalities. In those applications, the new AFEs could
offer a significant cost advantage. Because the new devices could potentially
be 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 a
disposable 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 are
already building medical products that use variations of the new technology.
Imec, a Belgium-based
nanoelectronics company, has already built a smart
ECG
necklace that can be worn around a person's neck like an ID badge. The
smart ECG necklace, which works with two electrodes attached to the body, embeds
a beat detection algorithm and is already being employed for ambulatory cardiac
monitoring.
The Holy Grail, however, is still the creation of ECG systems in
a small stickable bandage. By rolling the AFE chips together with a wireless
transceiver and four or five small electrodes inside the bandage, engineers
could eliminate the jumble of crisscrossed wires that's normally associated
with ECGs.
"People who get an electrocardiogram won't
need to be wrapped up in leads anymore," O'Doherty says.
If the technology receives
widespread adoption, it could also open the door to a multitude of other
possibilities. Temperatures, blood pressure measurements and respiration, along
with ECGs, could all be done by a stickable bandage.
"I know many customers who are
well along in their approval process," Burnham says. "Those products are
definitely on their way."
Health Reform Drives Material Changes
Just as new
technologies are changing the way designers develop products for the medical
industry, so too are regulations - particularly in the area of materials
selection.
Industry experts interviewed by
Design News see these specific trends in materials' selection:
- A major escalation in the battle to fight the spread of infectious
diseases in hospitals through use of antimicrobial compounds and materials that
can better tolerate demanding cleaning processes;
- Investigation of increased home-based health care; and
- More efficient use of operating room resources through better
identification of instruments.
"The health care industry is
in a period of dramatic change due to urgent calls for quality improvements and
cost reduction," says Thomas O'Brien, global product marketing director, health
care, Sabic Innovative Plastics. "Medical device manufacturers are right in the
middle of this process and are looking for answers from suppliers - including
new ways to design and manufacture to achieve the highest quality, meet new
regulatory requirements, support new care approaches and drive down costs."
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Fighting infections in
hospitals may be the top immediate priority. In 2009, Medicare said it would no
longer pay hospitals for additional costs to treat hospital-acquired
infections. As a result, hospitals are declaring an all-out war on germs.
Two major producers of transparent
plastics are rolling out new tougher grades.
"We understand that this
market is changing," says Carmen Rodriguez, business manager, resin products at
Altuglas International Resin, part of the Arkema group. "New developments
dictate that we take a different approach."
Altuglas International has developed what it describes as the
next generation of impact acrylic polymers for use in transparent disposable
medical devices. They are said to offer improved resistance to environmental
stress cracking (ESC), excellent gamma sterilization resistance and good melt
processability. Target applications include drug delivery applications as
infusion systems, stopcocks, manifolds, luers, and intravenous (IV) and syringe
components.
Arkema says the polymers' superior resistance to isopropyl
alcohol (IPA) is particularly important because of patient safety guidelines
aimed at preventing catheter-related blood stream infections that require new
disinfecting techniques. One of those techniques is rigorous cleaning of
intravenous lines.
Evonik Cyro is now marketing an acrylic-based multipolymer
compound that uses a proprietary silver-based antimicrobial agent to kill germs
on the surface of medical equipment. The compound targets FDA-regulated Class I
or Class II medical devices covered by 501(k) submission. Evonik Cyro expects
the materials to be used in place of existing acrylic compounds, polycarbonate
or polyvinyl chloride (PVC).
George Pape, head of medical and pharma in North America for the Clariant Masterbatch Business, says he also sees renewed interest in
antimicrobial compounds for medical applications. "Everything is pretty much
done 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 materials
selection in the medical market.
"More efficient use of operating room resources requires quick
visual confirmation and improved inventory tracking and management" says Judy
Melville, industry manager at Solvay Advanced Plastics.
One method for quick visual confirmation is using colors to
distinguish different medical instruments or components. That can be tricky for
medical applications because many plastics are colored with dyes, which can
migrate to the surface of molded products.
Clariant is introducing Mevopur color concentrates and pre-color
compounds, whose ingredients have been biologically evaluated against USP parts
87 and 88 (Class VI devices). Clariant also recently launched a new range of
globally harmonized standard colors for polypropylene and polyethylene, as well
as other materials such as polyether block amide plastic, where ingredients
have 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 of
such items. The company estimates that supply chain expenses as a percentage of
cost of goods is 39 percent for medical devices, compared to 3 to 6 percent for
retail stores.
One technology on display at MD&M West that has significant
potential to boost RFID use in medical devices is called 3D-MID. Harting
Mitronics is producing three-dimensional injection-molded RFID tags based on 3D-MID (MID is an acronym for molded
interconnect device). A laser activates the surface of a plastic part made with
specially engineered plastics. Then, the activated surface area is chemically
plated to create the antenna. The process is called LPKF LDS (laser direct
structuring).
Another megatrend in the
medical market is at-home care. Moving patients out of the hospital, when
possible, reduces costs and decreases risks of infection. Several exhibitors at
MD&M West showed portable medical devices for home or field use that employ
lightweight plastics for housings and other components that previously have
been made from metals.
One example is the Inogen One G2 System, a second-generation portable
oxygen concentrator. Compared to its predecessor, it's 40 percent smaller, 25
percent 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 with
many different grades of resin to find the best quality molded parts for our
application." The portable device's
shell is constructed of six separate components molded from Bayer
MaterialScience LLC's Bayblend FR 3010 polycarbonate/
acrylonitrile-butadiene-styrene (PC/ABS) plastic. The external battery housing
is also made of three components molded from the same polycarbonate blend.
Look for challenges on materials' technology to escalate as the
effort to improve health care and reduce costs intensifies.
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