shape memory alloy valves for emerging applications in the
TRANSCRIPT
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A C T U A T I O N | F L U I D I C S
W W W . M E M E T I S . C O M
Shape memory alloy valves for emerging applications in the Life Sciences
Microfluidics Symposium:Addressing Challenges in Life Science Fluidics
January 19th, 2021
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Life Sciences leave the centralized labs and become broadly available -compact devices for research and analytics increase in functionality
Valves from memetis make even complex analysis devices so compact that they can perform tests directly at the point-of-care - no tedious waiting time for results from a central laboratory
Find out immediately if you are healthy or need treatment
Introduction
Tailor-made medicine and therapy
Valves from memetis enable the safe and automatic operation of cell culture platforms - testing drugs and therapies on-the-chip
Due to their small footprint, the valves are suitable for established 96-well plates andcan help to develop new drugs in 33% less time
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Diagnostics and medical treatment experience substantial change –becoming highly mobile to be used where they are needed
Get medical treatment - when you need it and where you need it
Light and silent
Complex medical treatment devices are heavy and bulky due to a multitude of valves and other components.Microfluidic technology from memetis makes the devices small and portable, so that they can be taken to remote locations and used almost anywhere.
Valves from memetis are so small and energy-savingthat you can even wear them on your body - e.g. in devices for diabetes therapy - without any annoying heat or noise
Introduction
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Introduction
Innovation in many Life Sciences markets driven by Active Fluidic Control
POINT-OF-CARE CELL CULTURE DRUG DELIVERY SYSTEMS
MEDICAL DEVICES LAB-/ ORGAN-ON-CHIP DNA / PEPTIDE RESEARCH
‣ Mobile applications require compact devices with densely packed valves and pumps
‣ Example: On-site virus testing
‣ Successful cell culture development enabled by precise control over growth conditions
‣ Examples: pharmaceutics development, cancer research
‣ Wearing comfort and patient life quality demand lightweight, low-maintenance and silent devices
‣ Long battery life desired‣ Example: insulin dosing
‣ Need for silent operation and highest reliability
‣ Examples: Kidney dialysis control
‣ Additional functionality required to establish realistic conditions
‣ Low heat introduction by valves‣ Example: Blood-brain-barrier
research
‣ Large libraries of liquid constituents need to be dosed and mixed
‣ Low internal volumes save expensive reagents / samples
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Use Case: Pharmaceutics Development
• Pharmaceutical drugs synthesized by living cells• Examples: vaccines, allergenics, gene therapies, tissues, proteins, living medicines for cell
therapy• Challenge: identification and scale-up of cell lines with highest performance
Biological drug development is accelerated by early cell line selection
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Use Case: Pharmaceutics Development
https://www.cytena.com/wp-content/uploads/2020/09/cytena-AppNote_cbird_correlation_09022020V1.pdf
• cytena solution (c.birdTM): create optimum growth conditions already on 96-well-plate level
• Cell cultures based on standardized 24- and 96-well-plates• Patented mixing technology establishes homogeneous growth
conditions within each well, that are otherwise only achievable by large-scale shakers
• Early cell line selection saves months of drug development time
Next-generation of high-throughput Microbioreactor
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Future perspective: active well-by-well fluidic control
96-valve-array will allow individual control over growth conditions in each well
• Limited installation space per valve: 9x9 mm² per well
• Up to 96 valves to be operated at once à low energy consumption required
• Heat dissipation has to be strictly limited to protect cell cultures
• Cross-talk to be omitted• Compatibility with disposable 96-well-
plates required
Vision
• Highly compact, biocompatible miniature valves
• Bistable functionality
Solution
Use Case: Pharmaceutics Development
Challenges
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Active Fluid Control by Shape Memory Actuation
Active fluidic control needs appropriate actuation technology
• Industry standard: Solenoid valves based on electromagnetic actuation
• Miniaturization of solenoids is limited by physical operation principle
• Solution: Shape Memory Alloy (SMA) actuation as a complementing technology
• Electronic control of Solenoid and SMA-driven valves very similar
• First SMA wire-based valve products on the market
10+1
10-0
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10710-110-210-310-4 106105104103102101100
Mass [g]
Pow
er
densi
ty[W
/g]
Gas turbine
Hydraulicdrive
Petrol engine
Diesel drive
Marine engine
Pneumaticdrive
AC
Piezostack
SMA actuator
Electrorheologic
DC
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Shape memory alloys (SMA) are metallic alloys that can easily be deformed in cold state.As soon as they are heated, for example by electric current, they return to their memory shape
and thereby perform a movement.
Active Fluid Control by Shape Memory Actuation
Actuation by Shape Memory Alloys – the material is the machine
Easy deformation in cold state Heating induces shape recovery
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SMA actuator advantageous in terms of space, weight and shape
• Ultra-low installation space of film actuator
• Low weight due to mostly polymer parts• Low power consumption of thin actuator
Active Fluid Control by Shape Memory Actuation
SHAPE MEMORY ALLOY (SMA)
• Coil actuators always three-dimensional• Miniaturization potential has lower limit
• Mostly metallic parts make valve heavy• Power consumption usually > 1 W
SOLENOID (FOR COMPARISON)
Width: 1.6 mm
Length: 10 mm
Height: 0.02 mm
33% Volume saving*85% weight saving*50% power saving*
* memetis SMA valve compared to solenoid valves (most compact available normally-closed, media-separated valves)
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Dense packaging facilitated by SMA actuators without cross-talk
• No stray-fields impacting with application• Dense packaging without cross-talk
• Polarity-independent (+/- connectors) • Silent due to smooth movement
Active Fluid Control by Shape Memory Actuation
SHAPE MEMORY ALLOY (SMA)
• Magnetic fields reach outside valve housing• Cross-talk may occur when valves close
together• +/- Polarity has to be considered
SOLENOID (FOR COMPARISON)
Pitch: 5 mm
* http://www.hydraforce.com/HFinsider/Dual-Coil_Polarity_Issues/Dual_Coil_Polarity_Issues.htm
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Active Fluid Control by Shape Memory Actuation
• memetis shape memory technology allows for innovative and adaptable solutions
• Unique expertise in foil actuation only commercially available from memetis
MEMETIS EXPERTISE: PLANAR ACTUATION USING SMA FOILS
memetis actuators made from thin foils enable unique specifications
Variable mechanical integration ✓Extreme design freedom for customization ✓Customer specific actuator geometry (2D) ✓Large range of force and stroke ✓Smallest installation space ✓Highest work density ✓Easy electrical integration (low voltages) ✓Silent operation ✓Robust & reliable design ✓
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B
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F
SM
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ACTU
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Unique SMA actuators from memetis enable valves specifically designed for life sciences and challenging miniaturized tasks
Valving technology by memetis
NC-valve “Series 09“ Bi-stable valve
• Media-separated allrounder for microfluidics
• Usable as proportional valve (closed loop)
• Liquids and gases• Tight stacking by pitch of 5 mm• Low power consumption <0.2 W
• Ultra-power-saving valve• Media separated, similar to
NC/NO-Valve• Fast and power saving: Current
only for switching (<40 ms @ 1A)• Compatibility to 9x9 mm 96-
wellplate format is planned
Let us know about your
needs and participate in our poll!
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Valving technology by memetis
ACTUATION PRINCIPLE
LARGE FORCES IN SMALL
DIMENSIONS
FOIL ACTUATOR
INTEGRATED FLUIDIC SYSTEMVALVES
A
B
NO/ NC VALVE BISTABLE VALVE 3/4-WAY NC VALVE
• Pressure up to 2 bar• Life span >1,000,000 cycles• Ultracompact design• No switching noise (<20 dB)• Low internal volume (< 4 µl)
• Pressure up to 2 bar• Life span >1,000,000 cycles• Ultracompact design• No switching noise (<20 dB)• Low internal volume (< 4 µl)
• Pressure up to 2 bar• Life span >1,000,000 cycles• Ultracompact design• No switching noise (<20 dB)• Low internal volume (< 4 µl)
memetis offers wide range of solutions and
products
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Strong foundation for future growth – memetis in 60 seconds
Company overview
COMPANY RESEARCH CLIENTS
PERSONNEL CAPABILITIES AWARDS
‣ Founded 2017‣ One-Stop Shop from ideation to
series production‣ Own research and
manufacturing facilities
‣ > 20 years of research‣ > 50 topic-related scientific
publications‣ 6 patents / patent applications
‣ 55 % valve related clients‣ 32 % international clients‣ + 50.000 p.a. produced for
one client
‣ 13 employees‣ 3 PhD, 7 Master degrees,
3 Bachelor degrees‣ Interdisciplinary backgrounds
‣ Rapid prototyping via 3D, milling, laser cutting etc.
‣ Series production for up to 100.000 pieces p.a.
‣ 1st place Elevator Pitch BW‣ Cyber Champions Innovation‣ Finalist WECONOMY‣ 2nd Cyber One Award‣ 1st KIT Venture
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Have we sparked your interest? – Contact us!
Dr. Hinnerk Oßmerp: +49 721 47000240
Christoph Wessendorfe: [email protected]
EAGER TO MEET YOUR CHALLENGE
www.memetis.com
You want to stay up to
date on memetis’ products
and developments? FOLLOW US ON LINKEDIN!
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SPECIFICATIONS
NC valve “Series 09” – the media-separated allrounder
Appendix
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SPECIFICATIONS
Bistable valve – the ultra power-saving option
Appendix
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SPECIFICATIONS
Vent valve for gas control – high flow rate at low pressure
Appendix
• Developed for security application• In-wall mounting• Ideal for combination with piezo pump
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Appendix
Electronic control units and evaluation kits
• 5V USB-powered• Pre-programmed and adjustable current supply
profiles• Manual control via push button• Automated control via digital IO channels or I2C
interface
ü Two-channel version
included in evaluation kits
ü Suitable for monostable
and bistable valve variants
ü Eight-channel version will
become available in 2021
üAdd-on module will allow
control of up to 96 bistable valves
SPECIFICATIONS
Get startetnow!
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Appendix
Application-specific platform solutions
• Target applications: Research & development, academics, Start-ups, laboratory equipment
• Quick-start solution, e.g. for cell cultivation, process development, organ-on-chip
• Tailor-made and configurable systems for complex fluid control
• Selection of exchangeable fluid control and sensing modules
• Extendable plug&play solution
• Integration interface for custom fluidic chipsChip integration
Fluidic connectionMiniature valve Pump
Biocompatiblematerials
OFFER
Contact us for an
individual solution!
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SPECIFICATIONS
Various stand-alone actuation solutions
UA0203 UPSTROKE-ACTUATOR
Appendix
Examples: pinch valves,
disposable chip valves,
optics and sensor adjustment
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SPECIFICATIONS
Various stand-alone actuation solutions
TA0301 TILT-ACTUATOR
Appendix
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SPECIFICATIONS
Various stand-alone actuation solutions
IP0301 IN-PLANE-ACTUATOR
Appendix
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‣ Proportional control only closed loop investigated up to now
‣ Quality control 100% functionality test of flow rate and switching times @1 bar, RT
‣ Tests under harsh conditions for major design changes: T = 55 °C, storage conditions, vibration/impact
‣ Continuous control allows for exact regulation of flow rate even at flow-rates well below nominal value.
‣ Open-loop control to be tested regarding repeatability.
Proportional control characteristics
PROPORTIONAL CHARACTERISTICS
* increases power consumption
stand-alone valve. All three connections were tested up to a
pressure difference of 400 kPa and showed no leakage.
5 Characterization of the SMA multi-portmicrovalve
The characterization of the fluidic properties of the SMA
multi-port microvalve was first carried out in a tensiletesting machine. By this it is possible to measure simul-
taneously the force–displacement behavior required for
closing as well as the pressure-dependent flow rate. InFig. 12 the closing force and the pressure dependent flow
rate are shown as a function of the crosshead moving.
For a better understanding the individual steps aredescribed below: (I) A pressure difference is applied to the
inlet and the spindle of the tensile machine is moved
towards the valve seat until a force is detected. (I ? II)The force increases due to the elastic behavior of the
membrane and the applied pressure difference. At this state
the flow rate remains still at the pressure-depending valuedue to a sufficiently large flow-through area. (II ? III) As
the valve seat approaches, the force decreases rapidly, and
the flow rate drops to zero.These curves can be used to determine (1) the force
required by the actuator, (2) the force–displacement
behavior of the compression spring and (3) the expectedpressure-dependent flow rate. A force of 75 mN is required
to close or seal the valve for an applied pressure differenceof 50 kPa. If the pressure is increased, this necessary
closing force increases by about 1 mN per 1 kPa. Also the
flow increases from a value of about 1000 ml/min by about10 ml/min per 1 kPa.
5.1 Open loop control
The multi-port valves are suitable both for liquid media as
well as for gases. Figure 13 shows the flow of an NC SMAmulti-port microvalve as a function of the electrical heating
current at different pressure differences. To open the valve,
a minimum heating current of more than 100 mA is re-quired, which decreases for higher applied pressure dif-
ferences. For a heating current of 300 mA the valve is
completely open.The same measurement was also carried out with liquid
medium (water) and is shown in Fig. 14. The heating
currents for opening ([ 130 mA) as well as reaching acomplete open state ([ 400 mA) are higher compared to
Fig. 10 Photograph of an assembled SMA multi-port microvalvehaving outer dimensions of 12 9 11 9 9 mm3 (without tubingconnectors)
Fig. 11 Variants of fluidic connections for the SMA multi-portmicrovalve. a Flange connectors, b push-in fitting and c tubingconnectors
Fig. 12 Force (idle line) and flow (dotted line) depending on thedistance between a valve plunger and the valve seat for variouspressure differences
Fig. 13 Open loop control at one port of a SMA multi-portmicrovalve with nitrogen gas as test medium
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the gaseous media. The reasons for this are (1) the higher
viscosity of water and the associated higher closing forceas well as (2) an increased heat transfer.
5.2 Closed loop control
In addition to the static investigation of the valve behavior,
dynamic investigations were also carried out. In this case,three flow sensors with different properties were connected
between the pressure source and the inlet of the valve. Thedifferent sensors are necessary to measure the response
times as well as a precise flow rate with the same setup.
The control of the valve is realized by by a microcontroller(Arduino). Figure 15 shows the complete setup for flow
regulation consisting of the valve, the three flow sensors
(FS 1, FS 2 and FS 3) and the fluidic periphery.
5.3 Control results
Figure 16 shows the time-dependent closed loop-controlled
flow rate for 900 ml/min (@100 kPa) of the three flow
sensors and the required heating current. In this case a PIDcontrol was used. In particular, the proportional (P) and
integral (I) elements were heavily weighted, as the aim was
not to achieve particularly fast control, but to achieve apreferably exact control. The average heating current in
this case is about 200 mA.
5.4 Multi-port behavior
Table 1 shows the resulting flow rates for nominal flows of300 and 600 ml/min (nitrogen) in the inlet ports for an
applied pressure difference of 100 and 200 kPa and the
resulting flow in the common outlet port. The flow rate ofthe inlet and outlet ports are averaged over a time period of
30 s. The results show a control accuracy of 1 ml/min
deviation from the setpoint in the inlet ports. The higherdeviation of the common outlet is due to the read out of the
sensor signal. The blue color shows the measurements by
the MKS and the green color by the AWM flow sensor.Figure 17 shows the results of the same measurement
for a longer period (30 s), a setpoint value of 900 ml/min
and an applied pressure difference of 100 kPa.
Fig. 14 Open loop control at one port of a SMA multi-portmicrovalve with water (DI) as test medium
Fig. 15 Complete setup for flow regulation consisting of the valve,the three flow sensors (FS 1, FS 2 and FS 3) and the fluidic periphery
Fig. 16 Time-dependent flow rate (@100 kPa) of the three flowsensors and the required heating current
Table 1 Mixing behavior of nitrogen gas for different pressurizedinlet ports in a common outlet
Inlet 1 (ml/min) Inlet 2 (ml/min) Outlet (ml/min)
100 kPa 300.78 299.68 604.41
300.01 599.50 897.03
599.83 299.19 897.69
200 kPa 300.20 299.53 603.36
300.40 600.53 898.45
600.66 299.90 897.44
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the gaseous media. The reasons for this are (1) the higher
viscosity of water and the associated higher closing forceas well as (2) an increased heat transfer.
5.2 Closed loop control
In addition to the static investigation of the valve behavior,
dynamic investigations were also carried out. In this case,three flow sensors with different properties were connected
between the pressure source and the inlet of the valve. Thedifferent sensors are necessary to measure the response
times as well as a precise flow rate with the same setup.
The control of the valve is realized by by a microcontroller(Arduino). Figure 15 shows the complete setup for flow
regulation consisting of the valve, the three flow sensors
(FS 1, FS 2 and FS 3) and the fluidic periphery.
5.3 Control results
Figure 16 shows the time-dependent closed loop-controlled
flow rate for 900 ml/min (@100 kPa) of the three flow
sensors and the required heating current. In this case a PIDcontrol was used. In particular, the proportional (P) and
integral (I) elements were heavily weighted, as the aim was
not to achieve particularly fast control, but to achieve apreferably exact control. The average heating current in
this case is about 200 mA.
5.4 Multi-port behavior
Table 1 shows the resulting flow rates for nominal flows of300 and 600 ml/min (nitrogen) in the inlet ports for an
applied pressure difference of 100 and 200 kPa and the
resulting flow in the common outlet port. The flow rate ofthe inlet and outlet ports are averaged over a time period of
30 s. The results show a control accuracy of 1 ml/min
deviation from the setpoint in the inlet ports. The higherdeviation of the common outlet is due to the read out of the
sensor signal. The blue color shows the measurements by
the MKS and the green color by the AWM flow sensor.Figure 17 shows the results of the same measurement
for a longer period (30 s), a setpoint value of 900 ml/min
and an applied pressure difference of 100 kPa.
Fig. 14 Open loop control at one port of a SMA multi-portmicrovalve with water (DI) as test medium
Fig. 15 Complete setup for flow regulation consisting of the valve,the three flow sensors (FS 1, FS 2 and FS 3) and the fluidic periphery
Fig. 16 Time-dependent flow rate (@100 kPa) of the three flowsensors and the required heating current
Table 1 Mixing behavior of nitrogen gas for different pressurizedinlet ports in a common outlet
Inlet 1 (ml/min) Inlet 2 (ml/min) Outlet (ml/min)
100 kPa 300.78 299.68 604.41
300.01 599.50 897.03
599.83 299.19 897.69
200 kPa 300.20 299.53 603.36
300.40 600.53 898.45
600.66 299.90 897.44
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6 Conclusions and outlook
In this publication the integration of two individual SMA
foil actuators to a multi-port microvalve was shown for thefirst time. A 3/4-way valve was realized with mechanically
and electrically independent actuators that are fluidically
connected. The valve performance was investigated foroperation in an open as well as a closed loop control. The
presented valve layout in principle allows for extremely
compact integration of more than two valves in a commonhousing to increase the fluidic complexity. The membrane
(PDMS) and the fluidic part (PEEK) are made of bio-
compatible materials, whereby the valve can be used forin vitro biological investigations. In particular, the precise
mixing or separating of media is important for these pro-
cesses, as demonstrated in this publication. For the givenvalve concept different fluidic connections are presented
enabling to operate the valve as stand-alone device or to
flange it to fluidic periphery.Further improvements should be made to the flow con-
ditions to reduce the dead volume in the chamber and
pressure peaks in the outlet. Also it would be interesting tointerconnect to increase the fluidic complexity.
Acknowledgements This work was performed at the Institute ofMicrostructure Technology (IMT) at the Karlsruhe Institute ofTechnology (KIT) and the memetis GmbH. The authors thank M.Sc.Florian Bruderlin and Dr. Dario Mager for providing lab equipmentand helpful support.
References
Barth J, Krevet B, Kohl M (2010) A bistable shape memorymicroswitch with high energy density. Smart Mater Struct19(9):094004. https://doi.org/10.1088/0964-1726/19/9/094004
Barth J, Megnin C, Kohl M (2011) A bistable shape memorymicrovalve. In: Proceedings of IEEE MEMS 2011, Cancun,Mexico, pp 1067–1070
Barth J, Megnin C, Kohl M (2012) A bistable shape memory alloymicrovalve with magnetostatic latches. J Microelectromech Syst21:76–84
Braun S, Haasl S, Sadoon S, Ridgeway AS, van der Wijngaart W,Stemme G (2005) Small footprint knife gate microvalves forlarge flow control. In: Proceedings of Transducers 05, Seoul,Korea, pp 329–332
Bruus H (2008) Theoretical microfluidics. Oxford-University PressChluba C, Ge W, Lima de Miranda R, Strobel J, Kienle L, Quandt E,
Wuttig M (2015) Ultralow-fatigue shape memory alloy films.Science 348(6238):1004–1007
Chowdhury P (2018) Frontiers of theoretical research on shapememory alloys: a general overview. Shape Mem Superelasticity4(1):26–40
Fischer AC, Gradin H, Braun S, Schroder S, Stemme G, Niklaus F(2011) Wafer-level integration of NiTi shape memory alloywires for the fabrication of microactuators using standard wirebonding technology. In: 2011 IEEE 24th international confer-ence on micro electro mechanical systems, pp 348–351
Gradin H, Braun S, Stemme G, van der Wijngaart W (2012) SMAmicrovalves for very large gas flow control manufactured usingwafer-level eutectic bonding. IEEE Trans Ind Electron59:4895–4906
Grund T, Guerre R, Despont M, Kohl M (2008) Transfer bondingtechnology for batch fabrication of SMA microactuators. EurPhys. J Spec Top 158:237–242
Grund T, Megnin C, Barth J, Kohl M (2009) Batch fabrication ofshape memory actuated polymer microvalves by transfer bond-ing techniques. J Microelectron Electron Packag 6:1–9
https://www.memetis.com/https://www.kit.edu/https://www.openfoam.com/Johann Rupitsch S (2017) Piezoelectric sensors and actuators:
fundamentals and applicationsJohnson D (1991) Vacuum-deposited TiNi shape memory film:
characterization and applications in microdevices. JMM 1(1):34Johnson D (1994) Shape memory alloy film actuated microvalve
(US5325880 A). PatentKim H, Najafi K (2008) Electrostatic hydraulic three-way gas
microvalve for high-pressure applications. In: Twelfth interna-tional conference on miniaturized systems for chemistry and lifesciences
Lima de Miranda R, Zamponi C, Quandt E (2012) Micropatternedfreestanding superelastic TiNi films. Eng Mater 15:66–69
Megnin C, Kohl M (2014) Shape memory alloy microvalves for afluidic control system. J. Micromech Microeng 24:25001
Oh KW, Ahn CH (2006) A review of microvalves. J MicromechMicroeng 16:13–39
Olander A (1932) The crystal structure of AuCd. CrystallineMaterials
Rao A, Srinivasa AR, Reddy JN (2015) Design of shape memoryalloy (SMA) actuators. Springer
Ray C, Sloan C, Johnson D, Busch J, Petty B (1992) A silicon-basedshape memory alloy microcvalve. MAt Res Soc Symp Proc276:161–166
Thielicke E, Obermeier E (2000) Microactuators and their technolo-gies. Mechatronics 10(4):431–455
Yang B, Wang B, Schomburg WK (2010) A thermopneumaticallyactuated bistable microvalve. J Micromech Microeng 20:1–8
Publisher’s Note Springer Nature remains neutral with regard tojurisdictional claims in published maps and institutional affiliations.
Fig. 17 Time-dependent flow rate (30 s, @100 kPa) s and heatingcurrent
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Appendix