Fabrication of a dielectrophoretic chip with 3D silicon electrodes

Iliescu, Ciprian; Xu, Guo Lin; Samper, Victor; Tay, Francis Eng Hock

doi:10.1088/0960-1317/15/3/009

Cited by 91 publications

(79 citation statements)

References 20 publications

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“…Electrodes forming the channel were demonstrated using highly doped silicon. 21 Electrodes on the walls of an elliptical microfluidic channel were demonstrated using multi-step optical lithography involving glass wet etching and metal deposition. 22 Vertical electrodes in the sidewall of a rectangular micro-or nano-fluidic channel were demonstrated using multi-step optical lithography involving SU-8 with metal deposition and electroplating.…”

Section: Introductionmentioning

confidence: 99%

3-dimensional electrode patterning within a microfluidic channel using metal ion implantation

et al. 2010

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The application of electrical fields within a microfluidic channel enables many forms of manipulation necessary for lab-on-a-chip devices. Patterning electrodes inside the microfluidic channel generally requires multi-step optical lithography. Here, we utilize an ion-implantation process to pattern 3D electrodes within a fluidic channel made of polydimethylsiloxane (PDMS). Electrode structuring within the channel is achieved by ion implantation at a 40 angle with a metal shadow mask. The advantages of three-dimensional structuring of electrodes within a fluidic channel over traditional planar electrode designs are discussed. Two possible applications are presented: asymmetric particles can be aligned in any of the three axial dimensions with electro-orientation; colloidal focusing and concentration within a fluidic channel can be achieved through dielectrophoresis. Demonstrations are shown with E. coli, a rod shaped bacteria, and indicate the potential that ion-implanted microfluidic channels have for manipulations in the context of lab-on-a-chip devices.

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Section: Introductionmentioning

confidence: 99%

3-dimensional electrode patterning within a microfluidic channel using metal ion implantation

et al. 2010

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“…Compared with conventional electrode fabrication methods, this technique provides a simpler scheme to reliably install electrodes with flexible configurations at any position in 3D microfluidic structures. In addition to the development of the 3D continuous control of the electro-orientation of cells and particles, we expect that this technique can be extended to the fabrication of different types of electrofluidic devices for 3D dielectrophoretic manipulation of biological samples [51][52][53] , 3D electrorotation in microscale spaces 54,55 , and electrical impedance sensors 56,57 . The incorporation of photonic components, such as optical waveguides, fibers, and microlenses 38 , into the fabricated electrofluidic devices using the same fs laser would significantly enhance the performance of biochips, paving the way to 3D 'all-in-one' lab-on-a-chip devices.…”

Section: Resultsmentioning

confidence: 99%

Controllable alignment of elongated microorganisms in 3D microspace using electrofluidic devices manufactured by hybrid femtosecond laser microfabrication

Kawano

Liu

et al. 2017

Microsyst Nanoeng

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This paper presents a simple technique to fabricate new electrofluidic devices for the three-dimensional (3D) manipulation of microorganisms by hybrid subtractive and additive femtosecond (fs) laser microfabrication (fs laser-assisted wet etching of glass followed by water-assisted fs laser modification combined with electroless metal plating). The technique enables the formation of patterned metal electrodes in arbitrary regions in closed glass microfluidic channels, which can spatially and temporally control the direction of electric fields in 3D microfluidic environments. The fabricated electrofluidic devices were applied to nanoaquariums to demonstrate the 3D electro-orientation of Euglena gracilis (an elongated unicellular microorganism) in microfluidics with high controllability and reliability. In particular, swimming Euglena cells can be oriented along the z-direction (perpendicular to the device surface) using electrodes with square outlines formed at the top and bottom of the channel, which is quite useful for observing the motions of cells parallel to their swimming directions. Specifically, z-directional electric field control ensured efficient observation of manipulated cells on the front side (45 cells were captured in a minute in an imaging area of~160 × 120 μm), resulting in a reduction of the average time required to capture the images of five Euglena cells swimming continuously along the z-direction by a factor of~43 compared with the case of no electric field. In addition, the combination of the electrofluidic devices and dynamic imaging enabled observation of the flagella of Euglena cells, revealing that the swimming direction of each Euglena cell under the electric field application was determined by the initial body angle.

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“…Glass/silicon/glass structures Another structure of interest for transparent microfluidic devices is glass/silicon/glass, 98,99 where the glass layers form the ceiling and the floor of the microfluidic channel, while the silicon defines the walls. The microfluidic channels are defined using a deep RIE process (in this case, a small notching effect can occur at the silicon-glass interface 100 ). In order to perform a double anodic bonding, the first bonding process must be incomplete so that the wafer pair remains somewhat conductive.…”

Section: Anodic Bondingmentioning

confidence: 99%

“…Higher temperature also increases the conductivity of the stack, promoting the anodic bonding process. 100 …”

Section: Anodic Bondingmentioning

confidence: 99%

A practical guide for the fabrication of microfluidic devices using glass and silicon

Iliescu¹,

Taylor²,

Avram³

et al. 2012

Biomicrofluidics

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310

207

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This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow. I. WHY USE SILICON AND GLASS IN MICRO-AND NANO-FLUIDIC APPLICATIONS?Micro-and nano-fluidic technology continues to be embraced by biologists, 1-3 chemists, 4 and engineers throughout academia and industry. As its applications have expanded, there has been an explosion in the range of materials and processes used to fabricate these devices. The earliest microfluidic devices (e.g., gas 5 and liquid 6 chromatography devices) were made from silicon and glass and borrowed processes directly from semiconductor and microelectromechanical systems (MEMS) manufacturing. 7 Now, however, many researchers have moved away from silicon and glass, and instead use cast elastomers such as polydimethylsiloxane (PDMS)-which is ideal for swift prototyping-or thermoplastic polymers, which can be hot-embossed or injection-molded and are well suited to inexpensive manufacturing. Yet, there remain many applications where glass and silicon offer advantages over polymeric materials. In this paper, we highlight these advantages and offer a framework for selecting fabrication processes when using silicon and glass. A. The dominance of soft lithographyOver the last decade, PDMS has become virtually the default material for forming microfluidic devices, 8 because of the sheer ease with which it can be cast on to a micro-scale mould and then strongly bonded to glass. 9 The elastomeric nature of the material has been exploited to integrate fluidic valves and pumps on-chip and has simplified the production of multi-layer devices because the soft layers readily conform to each other. 10,11 Yet, the low stiffness (usually <1 MPa) of PDMS relative to amorphous thermoplastics, silicon, and glass has its own a) Authors to whom correspondence should be addressed. Electronic addresses: ciliescu@ibn.a-star.edu.sg and hkt@ntu.edu.sg. 6, 016505 (2012) drawbacks. High aspect-ratio channels are notoriously difficult to fabricate in PDMS because of their propensity to collapse. 12 Moreover, difficulties in automating the handling of such a soft material have hampered efforts to scale up PDMS device manufacturing. Meanwhile, PDMS's high oxygen and water permeabilities have proved both a blessing and a curse in different applications.The hydrophobic nature of PDMS can be an important consideration for some biological applications. In drug screening applications, for example, hydrophobic drugs as well as metabolites (urea or albumin) can be absorbed into the device's material due to hydrophobic--hydrophobic interaction...

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Fabrication of a dielectrophoretic chip with 3D silicon electrodes

Cited by 91 publications

References 20 publications

3-dimensional electrode patterning within a microfluidic channel using metal ion implantation

3-dimensional electrode patterning within a microfluidic channel using metal ion implantation

Controllable alignment of elongated microorganisms in 3D microspace using electrofluidic devices manufactured by hybrid femtosecond laser microfabrication

A practical guide for the fabrication of microfluidic devices using glass and silicon

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