A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection
- 7 December 2010
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Lab on a Chip
- Vol. 11 (5), 969-973
- https://doi.org/10.1039/c0lc00341g
Abstract
A three-layer poly (methyl methacrylate) (PMMA) electrophoresis microchip integrated with Pt microelectrodes for contactless conductivity detection is presented. A 50 μm-thick PMMA film is used as the insulating layer and placed between the channel plate (containing the microchannel) and the electrode plate (containing the microelectrode). The three-layer structure facilitates the achievement of a thin insulating layer, obviates the difficulty of integrating microelectrodes on a thin film, and does not compromise the integration of microchips. To overcome the thermal and chemical incompatibilities of polymers and photolithographic techniques, a modified lift-off process was developed to integrate Pt microelectrodes onto the PMMA substrate. A novel two-step bonding method was created to assemble the complete PMMA microchip. A low limit of detection of 1.25 μg ml−1 for Na+ and high separation efficiency of 77 000 and 48 000 plates/m for Na+ and K+ were obtained when operating the detector at a low excitation frequency of 60 kHz.Keywords
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