AVS 52nd International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI2-WeM

Paper BI2-WeM1
Fabrication of Well Structures with Electrode by Synchrotron Radiation Etching and Formation of Lipid Bilayer Giga-Ohm Seals

Wednesday, November 2, 2005, 8:20 am, Room 312

Session: Biomembranes and Spectroscopy
Presenter: Md. Rahman, The Graduate University for Advanced Studies, Japan
Authors: Md. Rahman, The Graduate University for Advanced Studies, Japan
R. Tero, NINS, Japan
Y.-H. Kim, The Graduate University for Advanced Studies, Japan
T. Yano, NINS, Japan
M. Aoyama, NINS, Japan
R. Sasaki, AISHIN SEIKI Co., Ltd., Japan
H. Nagai, AISHIN SEIKI Co., Ltd., Japan
M. Yoshida, AISHIN SEIKI Co., Ltd., Japan
T. Urisu, NINS, Japan
Correspondent: Click to Email
Supported membrane is a lipid bilayer supported on solid surfaces, and is useful as an artificial cell membrane for the study of biological reactions of membrane proteins. We are developing supported membrane biosensors for the purpose of developing the new research tool of the cell membrane surface reactions. These devices are interesting also from the view point of the application to the large scale screening method for the new medicine development. We have established a technique to fabricate a well-type microelectrode with about 1 µm diameter on the surface of a SiO@sub 2@/CoSi@sub 2@/Si substrate. The SiO@sub 2@/CoSi@sub 2@/Si was covered by Co contact mask by sputtering deposition. The circle pattern was made on the Co mask using the femto-second laser ablation. The SiO@sub 2@ was etched by synchrotron radiation (SR) etching. SR was used because of its unique features such as high spatial resolution, extremely high material selectivity between CoSi@sub 2@ and SiO@sub 2@, low damage, and clean etching atmosphere. AFM images of the SiO@sub 2@ surface after the removal of the Co mask with 0.1 M HNO@sub 3@ aq. showed that the surface was very flat (R@sub a@=0.8 nm). Ag (50 nm) was deposited by electroplating on the CoSi@sub 2@ which is exposed at the bottom of the etched well. Then the surface of the Ag was coated with AgCl also by electroplating. A single planar lipid bilayer (DPPC : POPS = 90:10) was deposited on these microelectrodes by the rapture of giant unilamellar vesicles. From the I-V characteristics of the membrane, the resistance of the lipid bilayer was 1.2 G@ohm@. This value was larger enough for the single channel current measurement. The measured capacitance was 10.7 pF, which is larger than that estimated from the total electrode area. This may be due to that the charge is accumulated at the larger area of the lipid bilayer than the area of just the electrode holes by the current through the thin (1 nm) water layer under the lipid bilayer.