Microfabrication of 3D Oblique Structures by Inclined UV Lithography

Han, Moon Gyu; Lee, Woonseob; Lee, Sung-Keun; Lee, Seung S.

doi:10.1007/978-94-010-0295-0_35

Cited by 14 publications

(18 citation statements)

References 1 publication

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“…Several works have demonstrated that higher IDEA thickness or height of the electrodes results in higher redox amplification factors [ 49 , 54 , 126 , 127 ]. In addition, increasing the surface area of IDEA-based sensors can be achieved in various ways, such as by fabricating pillars on top of the 2D IDEAs [ 128 , 129 ], by controlling the spin-coated thickness and shape of the photoresist carbon precursor material [ 54 , 130 , 131 , 132 , 133 , 134 ], and by growing vertically aligned carbon nanotubes (VACNT) on top of planar IDEA [ 135 , 136 ]. Interestingly, without increasing the extent of the IDEA’s thickness, the integrated microchannel [ 121 , 137 , 138 ] and combination with a mesh [ 139 ] on IDEAs does improve the amplification factor due to the large surface area of the redox cycling event.…”

Section: Micro and Nano Ideamentioning

confidence: 99%

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

et al. 2022

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Micro and nano interdigitated electrode array (µ/n-IDEA) configurations are prominent working electrodes in the fabrication of electrochemical sensors/biosensors, as their design benefits sensor achievement. This paper reviews µ/n-IDEA as working electrodes in four-electrode electrochemical sensors in terms of two-dimensional (2D) planar IDEA and three-dimensional (3D) IDEA configurations using carbon or metal as the starting materials. In this regard, the enhancement of IDEAs-based biosensors focuses on controlling the width and gap measurements between the adjacent fingers and increases the IDEA’s height. Several distinctive methods used to expand the surface area of 3D IDEAs, such as a unique 3D IDEA design, integration of mesh, microchannel, vertically aligned carbon nanotubes (VACNT), and nanoparticles, are demonstrated and discussed. More notably, the conventional four-electrode system, consisting of reference and counter electrodes will be compared to the highly novel two-electrode system that adopts IDEA’s shape. Compared to the 2D planar IDEA, the expansion of the surface area in 3D IDEAs demonstrated significant changes in the performance of electrochemical sensors. Furthermore, the challenges faced by current IDEAs-based electrochemical biosensors and their potential solutions for future directions are presented herein.

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Section: Micro and Nano Ideamentioning

confidence: 99%

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

et al. 2022

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“…Han et al [16,17] developed a UV exposure process in which a photomask and a SU-8 coated substrate are in contact and the mask/SU-8 is placed on a inclined/rotated chuck. They demonstrated various 3D microstructures such as oblique angled cylinders, embedded channels, bridges, V-grooves, truncated cones, and so on (Figure 1).…”

Section: Inclined Uv Exposurementioning

confidence: 99%

Innovative SU-8 Lithography Techniques and Their Applications

2014

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SU-8 has been widely used in a variety of applications for creating structures in micro-scale as well as sub-micron scales for more than 15 years. One of the most common structures made of SU-8 is tall (up to millimeters) high-aspect-ratio (up to 100:1) 3D microstructure, which is far better than that made of any other photoresists. There has been a great deal of efforts in developing innovative unconventional lithography techniques to fully utilize the thick high aspect ratio nature of the SU-8 photoresist. Those unconventional lithography techniques include inclined ultraviolet (UV) exposure, back-side UV exposure, drawing lithography, and moving-mask UV lithography. In addition, since SU-8 is a negative-tone photoresist, it has been a popular choice of material for multiple-photon interference lithography for the periodic structure in scales down to deep sub-microns such as photonic crystals. These innovative lithography techniques for SU-8 have led to a lot of unprecedented capabilities for creating unique micro-and nano-structures. This paper reviews such innovative lithography techniques developed in the past 15 years or so.

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“…First, a 150 nm thick chromium (Cr) layer is deposited on to a Pyrex glass wafer (Corning). After the Cr layer is patterned to define the shape of the microneedle, an SU-8 structure is formed on the Cr-patterned glass wafer by inclined UV lithography [21][22][23]. In this step, the SU-8 layer should be thicker than the desired height of the in-plane microneedle.…”

Section: In-plane Microneedlementioning

confidence: 99%

A novel fabrication process for out-of-plane microneedle sheets of biocompatible polymer

Han

Hyun²,

Park

et al. 2007

J. Micromech. Microeng.

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This paper presents a novel process for fabricating out-of-plane microneedle sheets of biocompatible polymer using in-plane microneedles. This process comprises four steps: (1) fabrication of in-plane microneedles using inclined UV lithography and electroforming, (2) conversion of the in-plane microneedles to an out-of-plane microneedle array, (3) fabrication of a negative PDMS mold and (4) fabrication of out-of-plane microneedle sheets of biocompatible polymer by hot embossing. The in-plane microneedles are fabricated with a sharp tip for low insertion forces and are made long to ensure sufficient penetration depth. The in-plane microneedles are converted into an out-of-plane microneedle array to increase the needle density. The negative mold is fabricated for mass-production using a polymer molding technique. The final out-of-plane microneedle sheets are produced using polycarbonate for biocompatibility by employing the hot embossing process. The height of the fabricated needles ranges from 500 to 1500 µm, and the distance between the needles is 500 to 2000 µm. The radii of curvature are approximately 2 µm, while the tip angles are in the range of 39-56 • . Most of the geometrical characteristics of the out-of-plane microneedles can be freely controlled for real life applications such as drug delivery, cosmetic delivery and mesotherapy. Since it is also possible to mass-produce the microneedles, this novel process holds sufficient potential for applications in industrial fields.

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Microfabrication of 3D Oblique Structures by Inclined UV Lithography

Cited by 14 publications

References 1 publication

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

Innovative SU-8 Lithography Techniques and Their Applications

A novel fabrication process for out-of-plane microneedle sheets of biocompatible polymer

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