Abstract
Electro-active polymers (or EAPs) are polymeric materials whose shapes are
modified when a voltage is applied to them. They can be used as actuators or
sensors. As actuators, they are characterized by the fact that they can
undergo a large amount of deformation while sustaining large forces. Due to
the similarities with biological tissues in terms of achievable stress and
force, they are often called artificial muscles, and have the potential for
application in the field of robotics, where large linear movement is often
needed.
When certain types of electro-active polymers are physically flexed, they
produce a voltage output. This effect allows EAPs to be used as potential
sensors in various types of equipment. With EAPs' inherent flexible and
durable nature, long sensor life is expected. EAPs such as ionic polymer metal
composites (IPMCs) are active materials that exhibit interesting bidirectional
electromechanical coupling phenomena, e.g., by bending an IPMC strip, a
voltage output is obtained, while a voltage input is able to cause the strip
to bend. Thus, they are also large motion sensors. The output voltage can be
calibrated for a standard-size sensor and correlated to the applied loads or
stresses. EAPs can be manufactured and cut in any size and shape. For example,
for a structural health monitoring of a bridge such as the San Francisco
Golden Gate Bridge against all vibrational, aerodynamics or natural
disturbances, a completely integrated and distributed computer-controlled
package of quickly installed, user-friendly IPMC sensor elements numbering
100,000 are required.
Electro-active ceramic actuators (for example, piezoelectric and
electro-strictive) are effective, compact actuation materials, and they are
used to replace electromagnetic motors. However, while these materials are
capable of delivering large forces, they produce a relatively small
displacement, on the order of magnitude of a fraction of a percent. Since the
beginning of the 1990s, new electro-active polymer (EAP) materials have
emerged that exhibit large strains, and they have led to a great paradigm
change with regards to their capability. The unique properties of these
materials are highly attractive for bio-mimetic applications such as
biologically inspired intelligent robots. Increasingly, engineers are able to
develop EAP actuated mechanisms that were previously imaginable only in
science fiction. Electric motors tend to be too weak, while hydraulics and
pneumatics are too heavy for use in robotics or prosthetics. EAPs, in
comparison, are lightweight, quiet and capable of energy densities similar to
biological muscles.
In ionic EAPs, actuation is caused by the displacement of ions inside the
polymer. Only a few volts are needed for actuation, but the ionic flow implies
a higher electrical power needed for actuation, and energy is needed to keep
the actuator at a given position. Examples of ionic EAPS are conducting
polymers, ionic polymer metal composites (IPMCs), and responsive gels. Yet
another example is a Bucky gel actuator, which is a polymer-supported layer of
polyelectrolyte material consisting of an ionic liquid sandwiched between two
electrode layers consisting of a gel of ionic liquid containing single wall
carbon nanotubes. The name refers to Buckyballs.
This study reports new concepts in mechanism design and digital mechatronics,
which have the potential to significantly impact a wide variety of systems and
devices, including medical devices, manufacturing systems, toys and robotics,
among others. The survey mainly targets dielectric elastomer actuators,
conductive polymers actuators and ionic polymer metal composites (IMPC)
actuators as the most likely candidates to act as EAP devices, on the basis
of material characteristics, maturity of technology, reliability, and cost to
meet design requirements of applications considered.
REPORT SUMMARY
Electro-active polymer technology could potentially replace common
motion-generating mechanisms in positioning, valve control, pump and sensor
applications, where designers are seeking quieter, power efficient devices to
replace cumbersome conventional electric motors and drive trains. An EAP
actuator is not only completely different from conventional electromechanical
devices, but also separates itself from other high-tech approaches that are
based on piezoelectric materials or shape-memory alloys by providing a
significantly more power-dense package and, in many instances, a smaller
footprint.
Shape-memory alloys contract with a thermal cycle, and piezoelectric
technologies expand and contract with voltage at high frequencies. While both
these technologies provide direct displacement, they are usually limited to a
1% direct displacement. Electromagnetic solutions typically consist of a motor
that rotates an output shaft, so there is no direct displacement from the
motor itself. The output shaft connects to a "drive train," gear reducer
transmission or other mechanical device that has several touching and moving
parts, which create an "indirect" displacement.
This iRAP (Innovative Research and Products, Inc.) study segmented markets
into four applications for electro-active polymer devices and products. These
are medical devices, smart fabrics, digital mechtronics, and high strain
sensing in construction. Manufacturers of electro-active polymers expect
competition to persist and intensify in the future from a number of different
sources. EAP devices are facing competition in a new rapidly evolving and
highly competitive sector of the medical market. Increased competition could
result in reduced prices and gross margins for EAP products and could require
increased spending by research and development, sales and marketing, and
customer support.
According to the iRAP study, during 2007, there is low key activity in the
manufacturing of EAP devices. Companies are catering to specific orders of low
to medium volumes. Low penetration of EAP technology in the fragmented market
is partly due to lack of standardization of product specifications among
manufacturers. Adaptation of EAP technology during the period of replacement
of bulky conventional actuators by OEMs will depend upon, besides cost,
reliability and durability of the EAP devices.
The global market for EAP actuators and sensors reached $15 million in 2007.
This will increase to $247 million by 2012. Medical devices will have the
largest share in 2007, as much as 77.3%, followed by smart fabrics with 13.3%,
digital mechtronics with 6.7%, and high strain sensing in construction as the
remaining 2.7% of the market. While the medical devices will continue to
maintain the lead in 2012, that sector will see the largest growth rate as
well, as much as 92 % AAGR from 2007 to 2012.
Major findings of this report are:
- There is low key activity in the manufacturing of EAP devices. Companies
are catering to specific orders of low to medium volumes. Low penetration of
EAP technology in the fragmented market is partly due to lack of
standardization of product specifications among manufacturers.
- Adaptation of EAP technology during the period of replacement of bulky
conventional actuators by OEMs will depend upon, besides cost, reliability and
durability of the EAP devices.
- The global market for EAP actuators and sensors reached $15 million in
2007. This will increase to $247 million by 2012.
- Medical devices will have the largest share in 2007, as much as 77.3%,
followed by smart fabrics with 13.3%, digital mechtronics with 6.7%, and high
strain sensing in construction as the remaining 2.7% of the market.
- While the medical devices will continue to maintain the lead in 2012, that
sector will see the largest growth rate as well, as much as 92 % AAGR from
2007 to 2012.
- Regionally, North America has about 66% market in 2007, followed by Europe
at 21.3%, Japan at 9.3%, and rest of world at 3.3%. The AAGR growth rate is
expected to be 71.3% to 91.8% for the four major regions surveyed for the
period 2007 to 2012.
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