AVS 51st International Symposium
    Semiconductors Thursday Sessions
       Session SC+EM-ThM

Paper SC+EM-ThM10
Direct Electronic Sensing of Biological Binding Events on Diamond Thin Films

Thursday, November 18, 2004, 11:20 am, Room 304B

Session: Wide Bandgap Semiconductors
Presenter: W. Yang, University of Wisconsin-Madison
Authors: W. Yang, University of Wisconsin-Madison
J.E. Butler, Naval Research Laboratory
J.N. Russell, Jr., Naval Research Laboratory
R.J. Hamers, University of Wisconsin-Madison
Correspondent: Click to Email
The chemical and physical inertness of diamond combined with its semiconducting electrical properties make it an attractive substrate for biological sensing. We have investigated the direct covalent modification of diamond with a variety of biomolecules including DNA and antibodies, and have investigated the relationships between the interfacial structure and the resulting electrical response observed upon DNA hybridization and antibody-antigen binding. The biological sensitivity and selectivity on diamond surfaces have been optimized using traditional fluorescence methods. By using electrical impedance spectroscopy (EIS), we have been able to detect DNA hybridization and antigen-antibody interactions in real time with high sensitivity. EIS measurements allow us to map out the impedance response as functions of both frequency and potential, helping to separate the electrical properties of the diamond space-charge region, the molecular layers, and the remaining solution. At low frequencies binding can be detected by the ion diffusion through the modified interfacial layers. At higher frequencies binding can be detected through a field effect induced in the diamond. The field effect mechanism allows us to directly detect biological molecules based on the different molecular charges. Complementary measurements on n-type and p-type silicon confirm the overall picture of the transduction process. Our results suggest the possibility of fabricating biological FET devices on diamond thin films.