Characterization of SU-8 for electrokinetic microfluidic applications

Sikanen, Tiina; Tuomikoski, Santeri; Ketola, Raimo A.; Kostiainen, Risto; Franssila, Sami; Kotiaho, Tapio

doi:10.1039/b503016a

Cited by 84 publications

(98 citation statements)

References 48 publications

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“…The SbF 6 2 is suggested to be the cause of the negative surface charge of SU-8. 29 We speculate that cations would be adsorbed or trapped by SbF 6 2 on Teflon or in SU-8, reducing electrowetting, especially when the bottom electrode is negatively biased. However, more studies are required to understand the physics of the phenomenon.…”

Section: Principle and Fundamental Studies Sessile Drop Experimentsmentioning

confidence: 94%

Asymmetric electrowetting—moving droplets by a square wave

et al. 2007

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Here droplet oscillation and continuous pumping are demonstrated by asymmetric electrowetting on an open surface with embedded electrodes powered by a square wave electrical signal without control circuits. The polarity effect of electrowetting on an SU-8 and Teflon coated electrode is investigated, and it is found that the h-V (contact angle-applied voltage) curve is asymmetric along the V = 0 axis by sessile drop and coplanar electrode experiments. A systematic deviation of measured contact angles from the theoretical ones is observed when the electrode beneath the droplet is negatively biased. In the sessile drop experiment, up to a 10u increment of contact angle is measured on a negatively biased electrode. In addition, a coplanar electrode experiment is designed to examine the contact angles at the same applied potential but opposite polarities on two sides of one droplet at the same time. The design of the coplanar electrodes is then expanded to oscillate and transport droplets on square-wave-powered symmetric (square) and asymmetric (polygon) electrodes to demonstrate manipulation capability on an open surface. The frequency of oscillation and the speed of transportation are determined by the frequency of the applied square wave and the pitch of the electrodes. Droplets with different volumes are tested by square waves of varied frequencies and amplitudes. The 1.0 ml droplet is successfully transported on a device with a loop of 24 electrodes continuously at a speed up to 23.6 mm s 21 when a 9 Hz square wave is applied.

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Section: Principle and Fundamental Studies Sessile Drop Experimentsmentioning

confidence: 94%

Asymmetric electrowetting—moving droplets by a square wave

et al. 2007

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“…Under these conditions, the electro-osmotic mobility of the background electrolyte and buffer in the presence of an SU-8 surface is approximately 5 10 À4 cm 2 V À1 s À1 . [14] The voltammograms exhibit initial oxidation and reduction peaks at AE 25 mV, before developing an ohmic shape at more anodic and cathodic potentials. This ohmic shape, which results from electrokinetic delivery of electroactive Fe(CN) 6 3/4À species driven by the potential applied at the EANEs, is characteristic of EANEs operated in this tightly coupled two-electrode configuration.…”

Section: Configuration 1: Single Working Electrode (Eane)mentioning

confidence: 99%

“…Devices studied in this work were constructed by milling highly anisotropic nanopores in membranes composed of SU-8 polymer insulating layers sandwiched around a Au EANE. As SU-8 exhibits varying electro-osmotic mobility with pH, [14] the faradaic current in these structures also varies with pH, indicating that electro-osmosis contributes strongly to the flux at higher pH values. The advective delivery of reagents to the EANE working electrode can increase steady-state currents up to 40 times, whereas nanofluidic confinement increases the efficiency of reactant-product conversion approximately tenfold over that obtained in a microchannel.…”

mentioning

confidence: 96%

Coupled Electrokinetic Transport and Electron Transfer at Annular Nanoband Electrodes Embedded in Cylindrical Nanopores

et al. 2014

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Convective mass transport is achieved in nanopore arrays containing embedded annular nanoband electrodes (EANEs) by using both two‐ and three‐electrode systems. In the two‐electrode configuration, the potential drop between the EANE and a counter/quasi‐reference electrode (CE/QRE) controls the electro‐osmotic flow (EOF). EOF enhances the rate of electron‐transfer reactions at an EANE array. Three‐electrode configurations, in which the EANE is placed between the CE/QRE and a second working electrode (WE2), are also studied. In the three‐electrode configuration, the position and magnitude of the current peaks are dependent on the WE2 potential. These shifts, which are characteristic of strong coupling between the EOF caused by WE2 and the faradaic processes monitored at the EANE, are explained by a combination of EOF and the concentration of analyte in the nanochannel. EOF is dictated collectively by the EANE and the WE2, because the potential at both electrodes is modified by substantial iR drops in the high‐resistance nanopores.

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“…3 SU-8 is a valuable material used in a wide range of applications such as optical waveguides for telecommunication; 4 microelectromechanical systems (MEMS) 5,6 including microuidic structures, 7,8 probes for microscopy 9,10 and molds for microembossing; 11,12 and microfabrication-based sensors. 13,14 Due to its chemical functionalization capability on demand and low cost, SU-8 is an attractive substrate candidate for the fabrication of bioanalytical micro and nano-devices.…”

mentioning

confidence: 99%

Development of a versatile biotinylated material based on SU-8

et al. 2013

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The negative epoxy-based SU-8 photoresist has a wide variety of applications within the semiconductor industry, photonics and lab-on-a-chip devices, and it is emerging as an alternative to silicon-based devices for sensing purposes. In the present work, biotinylation of the SU-8 polymer surface promoted by light is reported. As a result, a novel, effective, and low-cost material, focusing on the immobilization of bioreceptors and consequent biosensing, is developed. This material allows the spatial discrimination depending on the irradiation of desired areas. The most salient feature is that the photobiotin may be directly incorporated into the SU-8 curing process, consequently reducing time and cost. The potential use of this substrate is demonstrated by the immunoanalytical detection of the synthetic steroid gestrinone, showing excellent performances. Moreover, the naked eye biodetection due to the transparent SU-8 substrate, and simple instrumental quantification are additional advantages.

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Characterization of SU-8 for electrokinetic microfluidic applications

Cited by 84 publications

References 48 publications

Asymmetric electrowetting—moving droplets by a square wave

Asymmetric electrowetting—moving droplets by a square wave

Coupled Electrokinetic Transport and Electron Transfer at Annular Nanoband Electrodes Embedded in Cylindrical Nanopores

Development of a versatile biotinylated material based on SU-8

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