On-Chip Droplet Dispensing by a Magnetically Driven  Microtool

Yamanishi, Yoko; Kihara, Yuki; Sakuma, Shinya; Arai, Fumihito

doi:10.20965/jrm.2009.p0229

Cited by 13 publications

(6 citation statements)

References 11 publications

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“…Figure 4 shows the overview of PDMS chip, in the middle of this figure the blue long-hexagonal part is the chamber with an MMT installed in. The detailed method of fabrication and process flow is already published [23]. MMT is black and have a parallel plate structure.…”

Section: Concept Of On-demand and Size-controlled Chipmentioning

confidence: 99%

On-demand generation of droplet in size over a wide range by microfluidic control

Feng

Yamanishi

Arai

2009

2009 International Symposium on Micro-NanoMechatronics and Human Science

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We have successfully produced emulsion droplets on a chip with size-control and on-demand droplet generation by using magnetically driven microtool (MMT). The MMT has parallel plate structure to be constrained in translational motion. With a lateral motion of MMT in microchannels, the continuous phase can be cut into different size of droplets and the dispersed phase flow can inflow into the microchannels by the movement of MMT to obtain both of size-controlled and on-demand droplets actively. The size range of the produced droplet was improved three times as large as the previous system by employing novel hydraulic design of the chip, and also the leakage of the fluid was successfully prevented when it is chopped by using MMT.

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Section: Concept Of On-demand and Size-controlled Chipmentioning

confidence: 99%

On-demand generation of droplet in size over a wide range by microfluidic control

Feng

Yamanishi

Arai

2009

2009 International Symposium on Micro-NanoMechatronics and Human Science

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“…(MMT was actuated with the highest frequency (18 Hz) to cut droplet sufficiently. The relationship between MMT frequency and droplet size can be referred in the ref [23]) Figure 12(d) shows the hybrid MMT moving back to the initial position. The size of the produced emulsion droplet was in the range of 177.7 ± 2.3 Pm for the present condition.…”

Section: Emulsion Droplet Dispensing By Hybrid-mmtmentioning

confidence: 99%

Formation of microdroplets utilizing hybrid magnetically driven microtool on a microfluidic chip

Yamanishi

Feng

Kihara

et al. 2009

2009 IEEE International Conference on Robotics and Biomimetics (ROBIO)

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We proposed a polymer-metal hybrid MMT (magnetically driven microtool) which has properties of both elasticity and rigidity. A magnetic metal axle is made by electroplating, then it is mounted directly in the center of the MMT during molding. By using this process, we could fabricate a hybrid MMT whose fixed axes are elastic to move specific direction, while the center axle is rigid to prevent bending by the unwanted external force. The magnetic metal axle also has a merit to have higher magnetic property which contributes to the powerful actuation. We designed a hybrid MMT for on-demand droplet dispensing on a chip. It has a parallel plate structure to be constrained in translational motion. The displacement of the hybrid MMT was about 300 Pm which was 6 times larger than that of the conventional MMT, and on-demand droplet generation was successfully performed. We confirmed production of the 177.7±2.3 Pm droplet.

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“…Active materials for stimuli‐controlled microactuation can strongly improve the function of many applications related to lab‐on‐a‐chip devices, from the manipulation of single cells to controlling microfluidic systems. [ 1–4 ] Due to its thermoresponsive properties, poly( N ‐isopropylacrylamide) (pNIPAM) is an excellent material for generating actuators in aqueous environments. [ 5–7 ] The thermoresponsive properties of pNIPAM are based on a reversible phase transition at the lower critical solution temperature (LCST) due to a globule‐to‐coil transition.…”

Section: Introductionmentioning

confidence: 99%

Increasing the Efficiency of Thermoresponsive Actuation at the Microscale by Direct Laser Writing of pNIPAM

Spratte

Geiger

Colombo

et al. 2022

Adv Materials Technologies

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based on a reversible phase transition at the lower critical solution temperature (LCST) due to a globule-to-coil transition. [8] Below the LCST the polymer is in a hydrophilic, hydrated state, while above the LCST it is in a hydrophobic state. In this state, the interactions of the polymer with itself lead to a higher gain in free energy than would be achieved by solvation energy. The volume of pNIPAM materials in the hydrated, swollen state is much higher than in the hydrophobic state, because water is integrated into the material in the hydrated state. [9] As the actuation of pNIPAM hydrogel is based on its water-dependent shrinkage and swelling, the actuation efficiency and the forces generated by pNIPAM-based actuators critically depend on the in-and outflow of water through the pores of the material. Therefore, the actuation effect, including actuation dynamics as well as stroke forces, can be improved by introducing pores into the material. [10,11] Whereas in previous studies template-assisted methods have proven highly suitable for introducing pores into hydrogels, they lack local microstructural control, while being excellent for structuring macroscopic samples with an interconnected structure. [10] For generating highly efficient pNIPAM-based microactuators, a precisely defined design is required and thus methods are needed that allow for their highly precise 3D structuring at the micrometer scale.The technology of additive nano-and micromanufacturing opens doors to novel and remarkable microengineering possibilities and even enables printing of simple 3D volumetric structures at small scales. [12] Direct laser writing (DLW) involving two-photon polymerization of photoresists is one of the additive manufacturing techniques that can be used to fabricate intricate and miniaturized 3D structures, as they are required for the fabrication of microactuators. By utilizing twophoton absorption and a femtosecond pulsed laser, this fabrication method allows to print in sub-micrometer resolution, even with several materials and on different types of substrates. [13,14] Direct laser writing has also proven highly suitable for fabricating 4D materials, i.e., responsive materials that change their properties due to an external stimulus. [15] For example, the shape of such materials could be controlled at the micrometer scale by temperature and light. [16] Thermoresponsive hydrogels such as poly(N-isopropylacrylamide) (pNIPAM) are highly interesting materials for generating soft actuator systems. Whereas the material has so far mostly been used in macroscopic systems, here it is demonstrated that pNIPAM is an excellent material for generating actuator systems at the micrometer scale. Two-photon direct laser writing is used to precisely structure thermoresponsive pNIPAM hydrogels at the micrometer scale based on a photosensitive resist. This study systematically shows that the surface-to-volume ratio of the microactuators is decisive to their actuation efficiency. The phase transition of the pNIPAM is also demonstrated...

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On-Chip Droplet Dispensing by a Magnetically Driven Microtool

Cited by 13 publications

References 11 publications

On-demand generation of droplet in size over a wide range by microfluidic control

On-demand generation of droplet in size over a wide range by microfluidic control

Formation of microdroplets utilizing hybrid magnetically driven microtool on a microfluidic chip

Increasing the Efficiency of Thermoresponsive Actuation at the Microscale by Direct Laser Writing of pNIPAM

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