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`The Shape Memory Effect ‐ Phenomenon, Alloys and Applications
`
`
`
`Stoeckel
`
`
`
`Proceedings: Shape Memory Alloys for Power Systems EPRI
`pp. 1‐13
`
`
`
`1995
`
`www.nitinol.com
`
`47533 Westinghouse Drive Fremont, California 94539 t 510.683.2000 f 510.683.2001
`
`Letterhead (scale 80%) Option #1
`
`COOK
`Exhibit 1007-0001
`
`
`
`THE SHAPE MEMORY EFFECf • Phenomenon, AUoys and Applications
`
`Dieter Stoeckel
`NDC • Nitinol Devices & Components, Inc., Fremont, CA
`
`Introduction
`
`Certain metallic materials will, after an appanent plastic deformation. return to their original shape when
`heated. The same materials. in a certain temperature range, can be strained up to approx. 10% and still
`will return to their original shape when unloaded. These unusual effects are called thennal shape
`memory and superelasticity (elastic shape memory) respectively [I] . Both effects depend on the
`occurrence of a specific type of phase change known as thermoelastic martensitic transformation. Shape
`memory and supereJastic alloys respond to temperature changes and mechanical stresses in non(cid:173)
`conventional and highly amazing ways. They are, therefore, sometimes called "smart materials". The
`shape memory effect can be used to generate motion and/or force, while superelasticity allows energy
`storage. Both effects have fascinated scientists and engineers for almost three decades. drawing them to
`conferences and seminars in great numbers. However. very few developments made it to the market, and
`can be considered economic successes. Recent successes come mainly from medical applications
`utilizing the superelasticity and biocompatibility of Ni-Ti alloys.
`
`Shape Memory Effect
`
`"Shape Memory" describes the effect of restoring the original shape of a plastically deformed sample by
`heating it. This phenomenon results from a crystalline phase change known as "thermoelastic
`marten sitic transformation". At temperatures below the transformation temperature. shape memory
`alloys are martensitic, In this condition. their microstructure is characterized by "self-accommodating
`twins", The manensite is soft and can be deformed quite easily by de-twinning. Heating above the
`lransformation temperature recovers the original shape and converts the material to its high strength.
`austenitic. condition (Fig. 1).
`
`()
`
`---.., ,
`: , , ,
`• • • •
`
`Deformation
`
`Fig. I: Schematic representation of the shape memory effect and superelasticity
`
`COOK
`Exhibit 1007-0002
`
`
`
`The transformation from austenite to martensite and tbe reverse transformation from martensite to
`austenite do not take place at the same temperature. A plot of the volume fraction of martensite, or more
`practically. the length of a wire loaded with a constant weight. as a function of temperature provides a
`curve of the type shown schematically in Figure 2. The complete transfonnation cycle is characterized
`by the following temperatures: austenite start temperature (As). austenite finish temperature (Af).
`manensite stan temperature (Ms) and manensite finish temperature (Mf).
`
`If a stress is applied to a shape memory alloy in the temperature range between Af and a maximum
`temperature Md, martensite can be stress-induced. Less energy is needed to stress-induce and deform
`martensite than to deform the austenite by conventional mechanisms. Up to 10% strain can be
`accommodated by this process (single crystals of specific alloys can show as much as 25% pseudoeJastic
`strain in cenain directions). As austenite is the tbennodynamically stable pbase at this temperature under
`no-load conditions, the material springs back into its original sbape when the stress is no longer applied.
`This extraordinary elasticity is also called pseudoelasticity or transfonnational superelasticity.
`
`It becomes increasingly difficult to stress-induce martensite at increasing temperatures above Af.
`EventUally, it is easier to defonn the material by conventional mechanisms than by inducing and
`defonning martensite. The temperature at which martensite is no longer stress-induced is called Md.
`Above Md, the alloys are defamed like ordinary materials. Thus, superelasticity is only observed over a
`narrow temperature range.
`
`Mt
`
`A.
`
`100
`.!!
`
`-'
`
`" ..
`OJ -c ~
`" :Ii ..
`1:: ~
`
`0
`
`M.
`
`At
`
`Temperature
`
`=
`1l
`III
`
`T>Al
`
`T<MI
`
`Strain
`
`Fig. 2 (left): Schematic representation of the hysteresis loop
`Fig. 3 (right): Stress/strain curves at different temperatures
`
`The design of shape memory components, e.g. fasteners or actuators, is based on the distinctly different
`stress/strain curves of the martensile and austenite, and their temperature dependence. Figure 3 shows
`tensile curves of a Ni-Ti alloy at various temperatures. While the austenitic curve (T>Md) looks like
`that of a "nonnal" material, the martensitic one (T <Mf) is quite unusual. On exceeding a first yield
`point, several percent strain can be accumulated with only little stress increase. After that, stress
`increases rapidly with further deformation. The deformation in the "plateau region" can be recovered
`thermally. Deformation exceeding a second yield point cannot be recovered. The material is then
`plastically deformed in a conventional way. At temperatures T>Af, again, a plateau is observed upon
`loading. In this case, it is caused by stress induced martensite. Upon unloading. the material transforms
`back into austenite at a lower stress (unloading plateau). With increasing temperature, both loading and
`unloading plateau stress increase linearly [2].
`
`2
`
`COOK
`Exhibit 1007-0003
`
`
`
`Shape Memory Alloys
`
`The shape memory effect as the result of a manensitic transfonnation has been known since the mid
`1950's, when the effect was discovered in copper base alloys. In the early sixties. researchers at the
`Naval Ordnance Laboratory found the shape memory effect in Ni-Ti alloys (Nitinol- Ni-Ti Naval
`Ordnance Lab). Today, these alloys are the most widely used shape memory and superelastic alloys,
`combining the most pronounced shape memory effect and superelasticity . corrosion resistance and
`biocompatibility, and superior engineering properties. Copper based alloys like Cu-Zn-Al and Cu-Al-Ni
`are commercially available. too. These alloys are less stable and more brittle than Ni·Ti. and therefore.
`although less expensive. have found only limited acceptance. In recent years, iron based sbape memory
`alloys have been widely advertised. However, with their limited shape memory strain. lack of ductility
`and other essential properties, these alloys will have to prove themselves as viable engineering
`materials.
`
`The transformation temperatures of shape memory alloys can be adjusted through changes in
`composition. Ni-Ti as well as Cu-Zn-AI alloys show transformation temperatures between -100°C and
`+ IOO' C, Cu-Al-Ni alloys up to 200' C. Unfortunately, Cu-AI-Ni alloys are not stable in cyclic
`applications. Some ternary Ni-Ti-Pd [3], Ni-Ti-Hf and Ni-Ti-Zr [4] alloys also are reported to exhibit
`transformation temperatures over 200°C. Although not commercially available today. these alloys could
`eventually expand the applicability of the shape memory effect to much higher temperatures. In the
`foUowing, only Ni-Ti alloys will be reviewed.
`
`The hystereSis is an important characteristic of the heating and cooling behavior of shape memory
`alloys and products made from these alloys. Depending on the alloy used andlor its processing, the
`transformation temperature as well as the shape of the hysteresis loop can be altered in a wide range.
`Binary Ni-Ti alloys typically have transformation temperatures (AO between O°C and lOO°C with a
`width of the hysteresis loop of 25' C to 4O' C. Copper containing Ni-Ti alloys show a narrow hysteresis
`of 7°C to 15°C with transformation temperatures (Af) ranging from 10°C to approx. 80°C. An
`extremely narrow hysteresis of 0 to 5°C can be found in some binary and ternary Ni-Ti aJ10ys eXhibiting
`a premartensitic transformation (commonly called R-phase). On the other hand, a very wide hysteresis
`of over 150°C can be realized in Niobium containing Ni-Ti alloys after a particular thennomecbanical
`treatment. Although low transformation temperatures (Af «O· C) can be reached with binary Ni-Ti
`alloys, those alloys tend to be brittle and difficult to process. For cryogenic uses, therefore,
`Fe-containing Ni-Ti alloys are commonly used.
`
`• Af
`
`....
`
`• M •
`• M!
`
`ShU [MPa]
`
`Fig. 4 (left): Influence of processing on the shape of the hysteresis loop (schematic)
`Fig. 5 (right): Influence of applied stress on the transformation temperatures
`
`3
`
`COOK
`Exhibit 1007-0004
`
`
`
`The standard thermomechanical processing of Ni-Ti alloys generates a steep hysteresis loop (a greater
`shape change with a lesser change in temperature), which generally is desirable in applications where a
`certain function has to be performed upon reaching or exceeding a certain temperature. Special
`processing can yield a hysteresis loop with a more gradual slope. i.e. a small shape Change with
`temperature. This behavior is preferred in appUcations where proportional control is required [5].
`
`The shape of the hysteresis loop is not only alloy and processing dependent, but is also influenced by
`the application itself. IT a wire (standard processing) works against a constant load, e.g. by lifting a
`cenain weight, the transition from manensite t.o austenite or vice versa occurs in a very narrow
`temperature range (typically SoC). However, if the wire works against a biasing spring, the transition is
`more gradual and depends on the rate of the spring.
`
`Englneerlng Aspects
`
`The shape memory effect can be used to generate motion andlor force. while superelasticilY can store
`deformation energy. The function of the differeD( events as shown the stress/strain perspective in Fig. 6
`[6] can be explained in simple tenns using the example of a straight tensile wire. The wire is fIxed at
`one end. Stretching it at room temperature generates an elongation after unloading. The wire remains in
`the stretched condition until it is heated above the transformation temperature of this particular alloy. It
`will then shrink. to its original length As no load is applied, tbis is caUedfree recovery. Subsequent
`cooling below the transformation temperature does not cause a macroscopic shape change.
`
`If, after stretching at room temperature, the wire is prevented from returning to its original length, Le. if
`constrained to the extended length upon heating above the transformation temperature, it can generate a
`considerable force. This so-called constrained recovery is the basis of many successful applications [7].
`
`Motion
`
`Force
`
`MotionIForce
`
`•
`
`i
`
`•
`~
`
`T
`
`T
`
`Strain
`
`T
`
`I{
`
`Strain
`
`Fig. 6: Shape memory events in the stress/strain perspective [6]
`
`If the opposing force can be overcome by the sbape memory wire, it will generate motion against a
`force, and thus do work. Upon beating, the wire will contract and lift a load, for instance. Upon cooling,
`the same load will stretch the now martensitic wire and reset the mechanism. This effect is called
`two-way-effect with external reset force [8].
`
`Depending on the kind of biasing mechanism, different force/displacement characteristics can be
`obtained [9]. In Figure 7, five commonly used scenarios are compared with regard to the foreel
`displacement response. The level of the force in Fig.7a obviously is given by the weight of the "dead
`load", while the slope of the force/displacement line in Fig.7b represents the spring rate of the biasing
`steel spring. In Fig.7c, two shape memory wires are working in opposing directions. When wire 1 is
`heated (e.g.by electrically heating). it contracts, moves an object, and simultaneously stretches wire 2.
`
`4
`
`COOK
`Exhibit 1007-0005
`
`
`
`The object can be moved in the opposite direction by heating wire 2 after cooling of wire I. Socalled
`reverse biasing is shown in Figure 7d and e. The magnet causes the shape memory wire to generate a
`high static force, that drops sharply when lhe magnet is separated from its holding plate. A slower drop
`in force can be achieved by using a cam arrangement with a decreasing lever during actuation of the
`shape memory wire. Reverse biasing is beneficial when rugh cyclic stability is important.
`
`j t---
`
`DlsplKement
`
`DI.plK.......,t
`
`Dllpler:;ement
`
`Fig. 7: Biasing Mechanisms and their effect on force/displacement characteristics [9)
`
`Under optimum conditions and no load the shape memory strain can be as high as 8%. However, for
`cyclic applications the usable strain is much less. The same applies for the stress; for a one-Lime
`actuation the austenitic yield strength may be used as maximum stress. Much lower values have to be
`expected for cyclic applications.
`
`Shape memory alloys can, under certain conditions. show a true two-way-effect. which makes (hem
`remember two different shapes. a low and a high temperature shape. even without external force [10] .
`However, it is smaller and its cyclic behavior is not as well understood as that of the one-way-effect.
`Because there is no special treatment necessary. the cyclic use of the one-way-effect with external reset
`force in many cases is the more economic solution.
`
`The forth event is superelasticity. A wire is loaded at temperatures above Af. but below Md. After
`reaching the ftrSt yield point, it can be elongated to approx. 8 % strain with no significant stress
`increase. Upon unloading. the wire recovers its original length elastically. although with a stress
`hysteresis.
`
`Strain
`
`Fig. 8 (left): Tensile behavior of a superelastic wire at different temperatures
`Fig. 9 (right): Comparison of the flexibility of a stainless steel and a superelastic wire
`
`5
`
`COOK
`Exhibit 1007-0006
`
`
`
`Applications of Shape Memory and Superelastic AUoys
`
`In the following, applications will be categorized according to the function of the shape memory alloy
`itself, as suggested by Duerig and Melton [6]. The early product development history of Ni-Ti bas been
`full of failures and disappointments [II]. This can be attributed to the lack of understanding of the
`effects and the unavailability of engineering data. unreliable melting techniques and plain over(cid:173)
`expectation. One major disadvantage of shape memory is its spectacular showing. It shows off as jf it
`could solve all the problems in the world (browsing through the patent literature February 1990
`reveals: vacuum cleaner, sleeping device. method oj manufacturing shoes, racket gut, shape recoverable
`fabric, diapers, roy boat, necktie. ai/cooler bypass valve, throttle mechanism. concrete processing
`method .... ). Obviously, it doesn' t. In the meantime, after many million Siost on attempts to build the
`perpetuum mobile and to compete with thermostatic bimetals and other alternatives, the technology
`final ly has come of age. Engineers understand the benefits, but also the limitations of the material.
`fab rication methods are reliable, and prices are at an acceptable level. Most new volume applications are
`based on the superelastic effect, which doesn't require as tight a transfonnation temperature control as
`the shape memory effect, as used for actuators, for instance.
`
`The first technical successes clearly were uses of the constrained recovery event for joining and
`fastening purposes [7]. fo the late sixties and early seventies, Raychem Corp. pioneered the development
`of tube and pipe couplings for aircraft, marine and other applications. The concept is straightforward: a
`sleeve is machined with an J.D. that is approx. 3% smaller than the diameter of the tubing it is designed.
`to join. It is then cooled to its martensitic state and radially expanded eight percent. making it large
`enough to slip over two tube ends. When heated, the sleeve shrinks onto the tube ends and, while
`generating a high force. joins the tubes. Most couplings are made from cryogenic Ni-Ti-Fe alloys and
`have to be stored in liquid nitrogen after expansion. While this does not seem to pose a problem for
`aircraft manufacturers, it is a logistics issue for most commercial users. Therefore. wide-hysteresis
`Ni-Ti-Nb alloys have been developed. which can be stored and shipped at room temperature after
`expansion at low temperatures, and have to be heated to 150°C for installation [13] . These alloys remain
`in their high strength, austenitic state even after cooling to below -20°C.
`
`:: I::
`
`Fig. 10: Coupling, machined and expanded (top),
`after free recovery (middle) and installed on a
`tube (bottom) (! 2]
`
`Fig. 11 : Cut-away view of a shape memory
`coupling installed on a stainless steel tube [12]
`
`6
`
`COOK
`Exhibit 1007-0007
`
`
`
`To join large diameter pipes, or to create high compressive stresses near weld joints of such pipes for
`fatigue improvement. presll1lined Ni-Ti-Nb wire or ribbon can be wound around the pipe and then
`thelTI1ally recovered. This wire wrap technology was recently developed by ABB [14] for nuclear
`applications. It has to be mentioned, however, that Ni-Ti cannot be used in the high temperature, high
`pressure lines of a PDR, because of severe hydrogen embrittlement.
`
`Wide hysteresis alloys are also used in a variety of fastening applications. For example, rings may be
`used to [IS]:
`•
`terminate electromagnetic shielding braid to connectors
`•
`tenninate heat shielding braid to oxygen sensors
`•
`fix the location of bearings or gears at any point on a shaft, if desired, locking in a controlled axial
`preload force
`• assembJe clusters of radially disposed elements by compressing them with controlled uniform radial
`pressure
`• provide very high retention forces and low contact resistance in high amperage connectors.
`
`Fig. 12: Electromagnetic shielding braid
`tennination with fastener rings [12]
`
`Fig. 13: Installing braid termination rings with
`conductive heating [12]
`
`Fig. 14: Heat shielding braid termination on
`oxygen sensor with fastener ring [IS]
`
`Fig. 15: High amperage pin/sock.et connector with
`fastener ring installed [16]
`
`A similar concept is used for ZIF (zero insertion force) connectors, [n a technically highly successful
`pinlsocket version of such a connector, a Ni-Ti ring surrounds the outward-bending tangs of a fork
`contact. When cooled (with liquid nitrogen, for instance), the ring weakens as it transforms to its
`martensitic phase. enabling the springy tangs to force it open. The mating pin then can be inserted or
`7
`
`COOK
`Exhibit 1007-0008
`
`
`
`removed freely. Nearly one million contacts have been produced for the Trident program [15]. Other
`connecton; incorporate U-shaped actuaton; that forte open a spring clamp when heated with a foil heater
`attached to the actuator [17].
`
`Fig. 16: Cryofit ® pin/socket connector [ 12]
`
`Fig. 17: Printed circuitboard connector [t 7]
`
`Shape memory actuators respond to a temperature change with a shape cbange [18]. The change in
`temperature can be caused by a change of ambient temperature or by electrically heating the shape
`memory element. In the first case, the shape memory alloy acts as a sensor and an actuator (thermal
`actuator). In the second case, it is an electrical actuator that performs a specific task on demand.
`Thermal as well as electrical shape memory actuators combine large motion, rather high forces and
`small size, thus they provide high work output. They usually consist of only a single piece of metal, e.g.
`a straight wire or a helical spring, and do not require sophisticated mechanical systems. Although
`originally considered most important, actuators are the technically and economically least successful
`applications of the shape memory effect, when measured as outcome vs. developmem effon. The
`reasons for the limited success of shape memory actuators are technical insufficiencies as wel1 as cost.
`Design requirements usually include transformation temperature on heating, reset temperature
`(hysteresis), force (stress), displacement (strain), cyclic stability (fatigue), response time on heating and
`cooling, dimensions, over-temperature and over-stress tolerance, etc ..
`
`NI-TI Spring
`
`LP
`Steel Spring
`
`M
`
`M'
`
`Fig. 18: Thermostatic control valve(cut-away)
`
`Fig. 19: as 18, function schematic [19]
`
`An example of a technically as well as (at least for the user) economically successful application of a
`thermal shape memory actuator is the thermal ly responsive pressure control valve in the Mercedes-Benz
`automatic transmission. To improve the shifting comfort, the shifting pressure of the transmission is
`reduced during cold start situations and increased again when the transmission reaches operating
`temperature [19]. Introduced in model year 1989 Mercedes cars, this system has operated extremely
`reliably. Why is this application so successful? The required Ai temperature is 60°C with a comfonable
`±SoC tolerance, the spring is completely immersed in the rransmission fluid, thus heating and cooling is
`
`8
`
`COOK
`Exhibit 1007-0009
`
`
`
`slow and very uniform. tbe required force is low (approx. 5 N), very small displacement, maximum
`ambient temperature is 130' C, only 20,000 cycles expected, This fortunate combination of design
`parameters is seldom found. There has been a wealth of suggested shape memory applications for
`automotive use, like the "sman idJe screw", carburetor ventilation valve, oilcooler bypass valve to name
`a few [20]. Other applications of thennal shape memory actuators marketed today include viscosity
`compensating devices, ventilation valves, anti-scald valves, flre detection and prevention devices. air
`conditioning and ventilation devices, elC ..
`
`Fig. 20: "Smart idle screw" (prototype) [20J
`
`Fig. 21: Carburetor venLilation valve (prototype)
`
`Fig. 22: OiJcoo!er bypass valve (prototype)
`
`Fig. 23: as 22, schematic function
`
`Fig. 24: Clogging indicators for oil coolers [21]
`
`Fig. 25: Automatic gas line shut-off valves [22]
`
`9
`
`COOK
`Exhibit 1007-0010
`
`
`
`Fig. 26: Anti-Scald valve
`
`Fig. 27: Motion mechanism in toys
`
`Electrical shape memory actuators have been suggested to replace solenoids, electric motors etc. By
`controlUng the power during electrical actuation, specific levels of force andlor specific positions can be
`maintained. A variety of valves, triggering devices, animated objects, toys etc. are presently being
`marketed. The integration of Ni-Ti wires in composite structures has been suggested, to aUow the
`structure to change shape on demand. These "smart composites" can a1so actively attenuate acoustic
`noise in structures by having fundamental control over structural stiffness. Strain-compliant shape
`memory composites can be used as integrated members in truss structures. perfonning passive and
`active roles in vibration and shape control. Recently, a system to dampen the low frequency swing of
`large antennas or reflectors during space shuttle maneuvers has been proposed, using a shape memory
`controlled hinge system [23].
`
`.- T
`- .....
`, ~ ... ......
`1
`-~ 4"'"
`
`I
`
`. ........
`
`b. Nfouleted Pol
`
`Fig. 28: Active damping system [23J
`
`Fig. 29: Smart composites for shape control [24J
`
`Limiting factors for the use of shape memory alloys in electrical actuators are the transformation
`temperatures available today and the lack of control over cooling timcs. In order to work properly, the
`Mf temperature of the shape memory alloy must be well above the maximum operating temperature of
`the actuator. Commercially available alloys that are suffiCiently stable in cyclic applications, have
`maximum transfonnation temperatures (Mf) of around 70°C. Thus, an electrical actuator made from this
`alloy would fail to reset when ambient temperarure reaches 70°C. Correspondingly, the actuator would
`self-Lrigger when ambient reaches its As temperature. For applications with high operating temperatures
`10
`
`COOK
`Exhibit 1007-0011
`
`
`
`(e.g. automotive), alloys with transformation temperatures well above 150°C are required. As mentioned
`above. Ni-Ti-Pd alloys with transformation temperatures up to 200°C might eventually become
`available.
`
`The use of shape memory actuator for robots has often been proposed, and several prototypes have
`been presented. However, as the shape memory effect is a thermal phenomenon, response time is
`dictated by the heating and cooling of the material. While heating can be controlled through the power
`supplied to the actuator, cooling is less controllable. Depending on the size of the actuator (wire
`diameter, mass). cooling times can be seconds to minutes.
`
`As mentioned earlier, applications using superelastic Ni-Ti have seen explosive growth during the last
`two years. with antennae. brassieres and eyeglass frames being the volume leaders, followed by dental
`archwires and guidewires. The first application of superelastic Nitinol was as orthodontic archwire
`during the 1 970s. The advantages that
`itinol provides over conventional materials, obviously are the
`increased elastic range and a nearly constant stress during unloading {25} .
`
`Superelastic Nitinol guidewires are increasingly used because of their extreme flexibility and kink
`resistance. They also show enhanced torquability (the ability to translate a twist at one end of the
`guidewire into a tum of nearly identical degree at the other end)[26]. thus significantly improving
`steerabi1i.ty. The low force required for bending the wire is considered to cause less trauma than stainless
`steel guidewires. Kink resistance and steerability are also the main reasons for using Nitinol in stone
`retrieval and fragmentation baskets. The shaft as well as the basketwires can be made from superelastic
`Nitinol.
`
`More recently. sbape memory and superelastic Nitinol alloys have been used very effectively for
`self-expanding stents. The small profile of the compressed Slenl facilitates safe. atraumatic placement of
`the stent. After being released from the delivery system. the stent self-expands either elastically or
`thennally and exerts a constant, genL1e radial force on the vessel wall.
`
`Fig. 30: Selt-expanding Nitinol stent [27]
`
`Fig. 3 1: Non-kinking microsurgical instrument
`
`Medical device manufacturers are increasingly using Nitinol in instruments and devices for minimally
`invasive procedures [28]. The concept is to enter the body with a minimum profile through small
`incisions with or withoUl a ponal, and then changing shape inside the body cavity. One of the first
`instruments to use superelastic Nitinol was Ihe Mi[ek Mammalok@ needle wire localizer, used to locate
`and mark breast tumors so that subsequent surgery can be more exact and less invasive [29]. The
`concept of constraining a curved superelastic component inside a cannula during insertion into the body
`is used in a variety of insuuments for minimally invasise surgery. Figure 32 shows a dissecting spatula,
`the curvature of which is increased by progressive extrusion of the superelastic blade. Different blade
`configurations are used for variable curvature suture and sling passers [30]. Instruments with deflectable
`
`II
`
`COOK
`Exhibit 1007-0012
`
`
`
`distal ends use curved supcrelastic components which are constrained in a cannula during insertion into
`the body and deployed once inside lhe body. Graspers, needle holders and scissors can be insened
`through straight trocar cannulae. Once inside the peritoneal cavity, they can change into their curved
`configuration, thus increasing the degrees of freedom for manipulation [31].
`
`(,-----... tj ........ o
`F
`
`Fig. 32: Retractable spatula [30]
`
`Fig. 33: Hingeless instruments [32]
`
`Tn a new electrosurgical device for transurethral ablation of prostatic tissue, radiofrequcncy energy is
`delivered directly into the prostate via two side-deploying needles. These needles, made from
`superelasLic NiLinol, are deflected from the axis of tbe catheter around a sharp bend to be deployed.
`radially through the urethral wall into the prostate tissue. After passing the guiding channel. they
`protrude straight out of the catheter tip [33]
`
`Hingeless instruments use the elasticity of spring materials instead of pivoting joints to open and close
`the jaws of grasping forceps or the blades of scissors. Because of their simple design without moving
`parts and hidden crevices, they are easier to clean and sterilize. A new generation of hingeless
`instruments uses superelaslic Nitinol for the actuating component of these instruments, which provides
`elasticity higher than stainless steel by at least a factor of 10. This results in an increased opening span
`andlor reduced displacement of the constraining tube for ergonomic handling. In many cases the
`functional tip can be a monolithic superelastic component, vs. multipJe intricate, precision machined
`components and linkages of conventional instruments. This allows the design of instruments with very
`small profiles [32].
`
`Long and thin instruments. e.g. like forceps used in urology. lend to be very delicate and can kink
`easily. destroying an expensive tool. Using supcrclastic NiLinol for the outer tube and a superelastic
`actuation rod, makes the instrument very flexible and kink resistant. Superelastic tubes have only
`recently been made available by different suppliers. They are also used for biopsy needles, e.g. for
`interventional computer tomography or magnetic resonance imaging. [0 these techniques Nitinol
`instruments can be clearly detected without artifacts (glow) [34].
`
`12
`
`COOK
`Exhibit 1007-0013
`
`
`
`References
`
`[I]
`
`T.W. Duerig, K.N. Melton, D. Stoeckel, C.M. Wayman: "Engineering Aspects of
`Shape Memory A11oys", Butterworth-Heinemann. 1990
`T.W. Duerig, R. Zadno, in [I] 369
`[2]
`[3]
`S.M. Tuominen, R.J. Biermann, J.o.Metais 1988,32
`J.H. Mulder et a1., Proe. of SMST (A.R. Pelton et a1. eds.) (1994) to be published
`[4]
`D. Stoeckel, Proe. ADPA Conr."Smart Structures" Washington (1990)
`[5]
`T.W. Duerig, K.N. Melton, Proe.SMA 86, Guilin ( 1986) 397
`[6]
`J.L. Proft, T.W. Duerig, in [IJ 115
`[7J
`D. Stoeckel, Advanced Materials & Processes, 138 (1990) Oct., 33
`[8J
`R.G. Gilbenson: "Working With Shape Memory Wires", Mondotronics 199 1
`[9J
`J. Perkins, D. Hodgson, in [1]195
`[IOJ
`T.W. Duerig, Proe. MRS Conf. Boston (1994) to be publishcd
`[II J
`"Tinel Shape Memory Alloys", RA YCHEM company literature
`[1 2J
`T.W. Duerig, K.N. Melton, J. Proft, in [1] 130
`[13]
`[l4J H. Kornfeld, in [4J to be published
`[ 15J
`D. Stoeckel, T. Borden, Metall 46 (1992) 668
`H.P. Kehrer, H. NuBkem, VDINDE "Actuator 94" Bremen (1994) 324 .............. .
`[16J
`[17J
`J.F. Krumme, Connection Technology, April (1987)
`[l8J D. Stoeckel, T. Waram, SPIE Vol 1543 "Active and Adaptive Optical Components" 1991,382
`[19J
`D. Stoeckel, J. Tinschert, SAE Technical Paper Series # 910805
`D. Stoeckel, Springs Vol. 30, Oct. ( 1991) 35
`[20J
`[21 J
`J.F. Terue, D. Stoeckel, Proc. "Actuator 92" VDINDE Bremen (1992), 100
`[22J
`"RRECHECK" MEMRYTECH company literature
`[23J
`T. Stevens, Mat. Eng., Vol. 108, OcL 1991 , 18
`[24J
`Proc. ADPA Conf "Smart Structures" Washington ( 1990)
`R. Sachdeva, S. Miyazaki, in [IJ 452
`[25J
`J. Stice, in [4J to be published
`[26J
`[27J
`ANGiOMED AG, company literature
`[28]
`A. Melzer, D. Stoeckel, in [4J to be published
`J.P. O'leary, J.E. Nicholson, R.F. Ganuma, in [IJ 477
`[29J
`[30J
`STORZ, company literature
`[31J
`P.P. PODlet, R. Zadoo, in [4J to be published
`D. Stoeckel, A. Melzer, Proc. 8th CIMTEC Florence (1994) to be published
`[32J
`TU A, VIDAMED Int'l, company literature
`[33J
`[34J
`D.H.W. GrOnemeyer, R.M.M. Seibel, "lnterventionelle Computenomographie" , Ueberreuter
`Wissenscbaft, Wien Berlin (1989) 308
`
`13
`
`COOK
`Exhibit 1007-0014
`
`