A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection.
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.
Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian, Liaoning 116023, China. liujs@dlut.edu.cn
Junshan
J
Liu
Junyao
J
Wang
Zuanguang
Z
Chen
Yong
Y
Yu
Xiujuan
X
Yang
Xianbin
X
Zhang
Zheng
Z
Xu
Chong
C
Liu
D004553:Electric Conductivity; D046209:Electrophoresis, Microchip / Q000295:instrumentation*; D008839:Microelectrodes; D010984:Platinum / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D018511:Systems Integration
D010984:Platinum; D019904:Polymethyl Methacrylate