Fabrication of a glass-implemented microcapillary electrophoresis device with integrated contactless conductivity detection

Abstract

Glass microdevices for capillary electrophoresis (CE) gained a lot of interest in the development of micrototal analysis systems (microTAS). The fabrication of a microTAS requires integration of sampling, chemical separation and detection systems into a microdevice. The integration of a detection system into a microchannel, however, is hampered by the lack of suitable microfabrication technology. Here, a microfabrication method for integration of insulated microelectrodes inside a leakage-free microchannel in glass is presented. A combination of newly developed technological approaches, such as low-temperature glass-to-glass anodic bonding, channel etching, fabrication of buried metal interconnects, and deposition of thin plasma-enhanced chemical vapour deposition (PECVD) silicon carbide layers, enables the fabrication of a CE microdevice with an integrated contactless conductivity detector. The fabrication method of this CE microdevice with integrated contactless conductivity detector is described in detail. Standard CE separations of three inorganic cations in concentrations down to 5 microM show the viability of the new microCE system.

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

“…46) or H 3 PO 4 (Ref. 47) can be added to the etching solution. The etch rate is a parabolic function of HF concentration and is strongly dependent on the glass composition; for Corning 7740, the etch rate in 49% concentration HF is around 8 lm/min (Ref.…”

Silicon Carbide BioMEMS

“…Amorphous-SiC was selected because of its very high resistance to etching in the 49% HF solution used to micromachine the glass substrate. Berthold et al used a similar a-Si/a-SiC dual layer etch mask to micromachine through substrate vias into glass substrates using a 5% HF/70% H 3 PO 4 solution to fabricate a microcapillary electrophoresis device [53]. In this structure, a thin (30 nm thick) a-SiC film was deposited over metal electrodes in the device to provide passivation as well as to insulate the electrodes to enable capacitive coupling to the liquid.…”

Silicon Carbide: A Biocompatible Semiconductor Used in Advanced Biosensors and BioMEMS/NEMS

“…Most compounds used for biochemical analysis do not possess a fluorescent functionality, and thus labeling with a fluorescent marker is required. Recently, the on-chip integration of electrochemical and conductivity detection has been reported [49]. A schematical drawing of the chip is shown in Fig.…”

“…Figure 9. Drawing of a microchemical detector containing electrophoresis separation and conductivity detection [49] Conductivity detection can be used for on-chip measurements. To avoid electrolysis and electrode fouling when the solution was in contact with the measurement electrodes, contactless conductivity detection was proposed.…”