Performance of a Magnetic Shape Memory Micropump
1,2
Chen ,
2
Barker ,
2
Müllner
Yueli
Sam
Peter
1Department of Chemistry, CUNY Queensborough Community College, NY 11364
2Department of Material Science and Engineering, Boise State University, 83725
Introduction
Objective /Design
•  Solid-state micropumps -a promising market for point of care
diagnostics, biomedical research and lab-on-a-chip test
devices. •  Desirable features of micropump: free from electrical
contacts, sealed within a potentially disposable lab-on-a-chip
unit, pumping without ancillary mechanical devices, precise
and sensitive over a wide range of volume, etc. Magnetic shape memory
(MSM) alloy Ni-Mn-Ga
elements: -  Strain up to 6%, through
twinning process, when
exposed to a magnetic
field. Twining boundary
-  Allow for a wide range of
precise volumes to be
C
x
A
z
delivered.
C
φ
-  Magnetic field can be
c
a
a
generated by an off-chip
c
source b
Objective: to carry out systematic experiments measuring the
pumping flow rate as a function of rotational speed of the magnet.
Perpendicular Magnetic
field from the diametrically
magnetized cylindrical
magnet.
Experimental Setup b
•  Top view of MSMA element
with twins produced by a
diametrically magnetized
cylindrical magnet.
•  MSMA micropump pumping:
the magnetic field creates a
cavity on the MSMA element.
The cavity moves along the
MSM element upon rotation
of the cylindrical magnet and
transports fluid.
K. Ullakko, L. Wendell, A. Smith, P. Müllner, G. Hampikian. Smart Mater. Struct., 2012, 21,
115020. The magnetic shape memory
micropump with Ni2MnGa element
was designed at Boise State
University by Kari Ullakko. The NiMn-Ga single crystal element was
grown in the Magnetic Materials
laboratory of Dr. Peter Müllner's
group.
Experimental Procedures/Results
Mechanism
•  Schematic side view of MSMA
element with twin structure of
localized shrinkage.
MSMA Micropump 1 mm •  When moved forward to test flow rate
of MSM micropump, MSM element
cracked.
•  Multiple cracks formed indicating that
the damage was not due to mechanical
overload.
•  SEM images of fracture surface of the
MSMA element exhibit ripples which
may correlate with twins.
•  Performed experiments to test
efficiency of the MSM micropump.
•  Diametrically magnetized
cylindrical magnet was turned by a
drill for approximate 4s.
•  Magnified view of MSM miropump
moving water from left to right.
•  The MSM miropump successfully
pumped water in both directions.
0.5 mm 0.5 mm •  Constructed micropump by a single component Ni-Mn-Ga
element.
•  MSMA micropump successfully delivered a drop of water
(≈0.05ml) in both directions.
•  Failure of the MSMA element could be caused by
following reasons:
- Impurity of the MSMA element.
- Turning magnet by a drill made twins move, and it
also caused the MSMA micropump vibrate.
Field Parallel to Face
- Fatigue life of Ni-Mn-Ga
is varied from 4,000 cycles u
810,000 Cycles
to 800,000 cycles. After NiInitial
Mn-Ga elements have been
cycled many times, twinning
activity would be reduced.
Magnetization (Am2/kg)
Procedures/Materials Conclusions/Discussion
Effective Magnetic Field (MA/m)
Future Work
•  Determine Fatigue life of Ni-Mn-Ga magnetic shape memory
alloys.
•  Prevent any sealants (Epoxy, Silicone and Sylgard) from
leaking into MSMA element to help render micropumps
effective.
•  Fasten diametrically magnetized cylindrical magnet right
under MSMA element to help increase efficiency of twins
motion.
•  Characterize flow rate, pressure, temperature and power
consumption of MSMA micrpumps.
References
(1) K. Ullakko, L. Wendell, A. Smith, P. Müllner, G.
Hampikian. Smart Mater. Struct., 2012, 21, 115020.
(2) A Smith, A. Saren, J. Jarvinen, K. Ullakko, Microfluid
Nanofluid, 2015, 18, 1255-1263.
(3)T. Lawrence, P. Lindquist, K. Ullakko, P. Müllner. Fatigue
life and fracture mechanics of unconstrained Ni-Mn-Ga single
crystals in a rotating magnetic field. Manuscript unpublished.
Acknowledgements
50 µm 0.2 mm The US National Science Foundation
supported this research at Boise State
University through project NSFIIP-1500240.