C-MEMS for bio-sensing applications

Song, Yin; Agrawal, Richa; Wang, Chunlei

doi:10.1117/12.2180127

Cited by 3 publications

(1 citation statement)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this process, a photolithographically-patterned organic precursor is reduced to GC at 900 °C in an oxygen-free environment [29]. The C-MEMS process for GC electrode fabrication has been successfully implemented for ACEO pumping [30], biosensing [31], energy generation [32] and energy storage [33], among others.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic channeling as a controlled flow reversal mechanism for bidirectional AC electroosmotic pumping using glassy carbon microelectrode arrays

Vázquez-Piñón

Pramanick

Ortega-Gama

et al. 2019

J. Micromech. Microeng.

View full text Add to dashboard Cite

Controlled bidirectional flow by AC electroosmotic means is achieved using asymmetric coplanar and high-aspect-ratio glassy carbon electrodes and without the involvement of moving elements. The forward and backward fluidic propulsion is the result of hydrodynamic channeling of the fluid in a microfluidic device. The asymmetric coplanar electrodes were fabricated by photolithographic patterning of SU-8 photoresist, followed by pyrolysis at 900 °C. Morphological characterization of the carbon structures was carried out by SEM and confocal microscopy. Then, Raman and EDX spectroscopies confirmed that the resulting carbon material is appropriate for electrokinetic applications. A finite element analysis was carried out to study the flow development by AC electroosmosis. Electrode arrays of three different asymmetry ratios (60 µm:20 µm, 80 µm:20 µm, and 100 µm:20 µm) were fabricated and tested. Fluid velocity was measured for an applied bias in the 2-20 V PP amplitude range, and in the 1 kHz to 200 MHz frequency range. Overall maximum measured forward and reverse fluid velocities were 28.59 µm s −1 and 338 µm s −1 , respectively. On an additional set of devices with the same asymmetry ratios, a second photolithography step was utilized to produce high-aspect-ratio microposts on top of the coplanar electrodes to study the effect of high electrode contact surface to generate bidirectional flow. Using the same amplitude and frequency ranges as for planar structures in experimental testing, the overall maximum measured velocities were 9.23 µm s −1 and 90.66 µm s −1 for the forward and reverse regimes, respectively. In contrast to the planar electrodes, microposts-containing electrodes had more balanced velocity magnitudes between reverse and forward flows as the asymmetry ratio increases. In this case, the use of this electrode topology can be useful when symmetry of the forward and backward flow is more important than the magnitude of the volumetric flow rate.

show abstract

Section: Introductionmentioning

confidence: 99%

Hydrodynamic channeling as a controlled flow reversal mechanism for bidirectional AC electroosmotic pumping using glassy carbon microelectrode arrays

Vázquez-Piñón

Pramanick

Ortega-Gama

et al. 2019

J. Micromech. Microeng.

View full text Add to dashboard Cite

show abstract

Microplasma direct writing for site-selective surface functionalization of carbon microelectrodes

et al. 2019

View full text Add to dashboard Cite

Carbon micro- and nanoelectrodes fabricated by carbon microelectromechanical systems (carbon MEMS) are increasingly used in various biosensors and supercapacitor applications. Surface modification of as-produced carbon electrodes with oxygen functional groups is sometimes necessary for biofunctionalization or to improve electrochemical properties. However, conventional surface treatment methods have a limited ability for selective targeting of parts of a surface area for surface modification without using complex photoresist masks. Here, we report microplasma direct writing as a simple, low-cost, and low-power technique for site-selective plasma patterning of carbon MEMS electrodes with oxygen functionalities. In microplasma direct writing, a high-voltage source generates a microplasma discharge between a microelectrode tip and a target surface held at atmospheric pressure. In our setup, water vapor acts as an ionic precursor for the carboxylation and hydroxylation of carbon surface atoms. Plasma direct writing increases the oxygen content of an SU-8-derived pyrolytic carbon surface from ~3 to 27% while reducing the carbon-to-oxygen ratio from 35 to 2.75. Specifically, a microplasma treatment increases the number of carbonyl, carboxylic, and hydroxyl functional groups with the largest increase observed for carboxylic functionalities. Furthermore, water microplasma direct writing improves the hydrophilicity and the electrochemical performance of carbon electrodes with a contact-angle change from ~90° to ~20°, a reduction in the anodic peak to cathodic peak separation from 0.5 V to 0.17 V, and a 5-fold increase in specific capacitance from 8.82 mF∙cm−2 to 46.64 mF∙cm−2. The plasma direct-writing technology provides an efficient and easy-to-implement method for the selective surface functionalization of carbon MEMS electrodes for electrochemical and biosensor applications.

C-MEMS for bio-sensing applications

Cited by 3 publications

References 25 publications

Hydrodynamic channeling as a controlled flow reversal mechanism for bidirectional AC electroosmotic pumping using glassy carbon microelectrode arrays

Hydrodynamic channeling as a controlled flow reversal mechanism for bidirectional AC electroosmotic pumping using glassy carbon microelectrode arrays

Microplasma direct writing for site-selective surface functionalization of carbon microelectrodes

C-MEMS Based Micro Enzymatic Biofuel Cells

Contact Info

Product

Resources

About