Artificial flagella: bio-inspired responsive polymers for micro-object manipulationCitation for published version (APA):Liu, D., Broer, D. J., Bastiaansen, C. W. M., & Toonder, den, J. M. J. (2009). Artificial flagella: bio-inspiredresponsive polymers for micro-object manipulation. Poster session presented at Mate Poster Award 2009 : 14thAnnual Poster Contest, .

Document status and date:Published: 01/01/2009

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Materials and MethodsMagnetite embedded polymer

The first version of our artificial flagella consists of a micro-flap with a

photo-curable polymeric material as the principle component, in which

magnetic nanoparticles are dispersed to achieve a magnetic structure.

Figure 2: Sketch of our first magnetically-actuated artificial flagellum

Using the compounds listed listed, and after polymerization, we observedthat the magnetical nanoparticles are dispersed quite evenly in thepolymer. See figure 3.

•Toluene based ferrofluid (magnetite) 28.6wt%

•2-Ethylhexylacrylate (base material) 61.0wt%

•1,6-Hexanediol diacrylate (crosslinker) 9.7wt%

•Irgacure 2959 (photo initiator) 0.7wt%

Polymer Technology

/ Department of mechanical engineering DPI #699

Artificial flagella: Bio-inspired responsive

polymers for micro-object manipulationDanqing Liu1, Dick Broer3, Kees Bastiaansen3, Jaap den Toonder1,2

IntroductionIn lab-on-a-chip devices in, it is important that one is able to accurately

move and position micro-objects to be analyzed (cells, organelles) within

the micro-fluidic features of the device. Nature has solved this problem by

means of active hair-like structures, known as flagella, which are able to

propel the cells to which they are attached, see figure 1.

Figure 1: Micro-organisms propelled by means of flagella

Figure 3: Optical microscopy image of magnetite dispersed in the polymer. The scale bar

indicates 50µm (left) and 5µm (right)

Figure 4: Schematic of the inkjet printing process (left) and the optical microscopy image

of the printing result (right). The original design is a 1mmx0.2mm rectangle, represented

as the dashed contour.

Magnetic ActuationFigure 5 shows the magnetic set-up used. Each coil is addressed with a

sinusoidal current that has a phase lag of 90˚ w.r.t. the adjacent coil. This

creates a rotating magnetic field between the coils, with a strength 40 mT.

ConclusionsWe demonstrated that the magnetite embedded polymer can be

structured via inkjet printing. After releasing from the substrate, our

artificial flagellum can be actuated using an external magnetic field.

ObjectiveInspired by nature, we aim to develop polymer based artificial flagella,

that can be actuated by a magnetic field. Also, we intend to attach these

to an object to create an artificial swimmer and control which the

swimming direction by another trigger such as temperature, PH or light.

After inkjet printing, the material is polymerized by UV light under

nitrogen flow. Figure 4 shows that the printing result is close to the

design. Finally, the flagella are released from the substrate using the

dissolution of a polyvinyl alcohol layer from underneath the flap.

Figure 6: Artificial flagelum rotates along with the magnetic field. Without magnetic field

(a) ; snapshots at different angles of field rotation (b) 90˚, (c)180˚, (d) 270˚, (e) 360˚

Figure 5: (a) Photo of the quadrupole used, (b) sketch of cross sectional view of the

quadrupole; the red arrow indicates the rotation direction of the magnetic field.

CH2=CH-C-O-CH2-CH2-CH2-CH2-CH2-CH2-O-C-CH-CH2

=O =O

CH2=CH-C-O-CH2-C-CH2-CH2-CH2CH3

=O

H

C2H5-

1TU/e MaTe, 2Philips Applied Technologies, 3TU/e SKT

Fabrication

Inkjet printing of the uncured mixture including the magnetic particles is

used to structure the flagella. Compared with the conventional

lithographic approach, inkjet printing reduces the processing steps and

the material used by depositing material on demand and in a direct way.

Using a microscope we took movies of our artificial flagellum placed

between the poles. The flagellum perfectly responded to the applied field.