AVS 51st International Symposium
    MEMS and NEMS Monday Sessions
       Session MN-MoP

Paper MN-MoP7
Development of a Disposable Microchip with Capillary Electrophoresis and Integrated Three-Terminal Electrochemical Detection

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: J.H. Kim, Myongji University, Korea
Authors: J.H. Kim, Myongji University, Korea
M.C. Moon, Myongji University, Korea
Y.S. Kim, Myongji University, Korea
Correspondent: Click to Email
We have developed a microsystem with capillary electrophoresis (CE) and electrochemical detector (ECD). The microfabricated CE-ECD systems are adequate for a disposable type and the characteristics are optimized for an application to the electrochemical detection. The system was realized with polydimethylsiloxane(PDMS)-glass chip and indium tin oxide (ITO) electrode. The injection and separation channels (80 m wide 40 m deep) were produced by moulding a PDMS against a micro fabricated master with relatively simple and inexpensive methods. ITO electrode was fabricated by patterning the ITO film deposited on a fusion glass. A capillary electrophoresis and a three-electrode electrochemical detector were fabricated on the same chip. Unlike analogous CE/ECD devices previously reported, no external electrodes were required. The surface of PDMS layer and ITO-coated glass layer was treated with UV-Ozone to improve bonding strength and to enhance the effect of electroosmotic flow. The running buffer was prepared by 10 mM 2-(N-morpholino)ethanesulfonic acid (MES) titrated to pH 6.5 using 0.1 N NaOH. The testing analytes are consisted of 1 mM catechol and 1 mM dopamine. Separation of catechol and dopamine was performed using an electric field strength of 60 V/cm after applying an injection electric field of 50 V/cm. The ECD circuit was adjusted to maintain a potential of +600 mV DC between the working and reference electrodes. The electrochemical detection circuit could mostly decouple the interference of a separation electric field. The root-mean-square noise level was ~10 pA on a signal 10 nA in 10 mM MES. The limit of detection for dopamine was ~0.5M The disposable CE/ECD system showed similar results with the previously reported expensive system in the limit of detection and peak skew. When we are using disposable microchips, it is possible to avoid polishing electrode and reconditioning.