SGER: The Fabrication of Biological Time Resolved Arrays of Chemical Energy Readers

University Of Delaware, Newark DE

Investigators

Abstract

0129535 Kolodzey The PI proposes to evaluate the performance of a novel bio-chemical sensor based on the electrochemical field effect in MOS-type transistor structures. He has fabricated prototypes of this MOS sensor, and have found that they produced non-linear current-voltage responses to DNA molecules in an aqueous solution. Calculations indicate that the device should be highly sensitive to the electrochemical potential of bio molecules such as DNA and proteins. It should be capable of nanosecond response times for time-resolved measurements. These preliminary results will be described briefly here and in more detail in the Motivation Section of this proposal. The operation of the sensor is based on the semiconductor surface field effect in MOS devices in which the electrochemical potentials (Fermi levels) of bio-compounds influence the electrical current flowing in a transistor-like device. The detected biomolecules are located within a Debye screening length of the gate insulator electrode. Calculations indicate that the proposed field effect device may be sensitive to less than 110 molecules per square micron of active sensor area. By reducing the active area to 100 nm square, which is within lithographic capabilities, the sensor may be able to detect the charge on one DNA molecule. The reason for the exploratory and high-risk status is that the PI has not yet performed a comparison of sensor responses with different types of DNA and other biomolecules. He has not yet measured the time resolved response. The sensitivity is unknown, and it is uncertain if the sensor can distinguish different concentrations and different types of DNA. For this SGER proposal, the PI wants to measure the sensor response with different types of DNA to determine its sensitivity and selectivity. The measurements will be calibrated with an optical fluorescence microscope. If it turns out that this bio-chemical sensor is a valuable instrument that can yield useful information on biomolecules, he plans to submit a full proposal for a comprehensive research program. A comprehensive proposal based on this sensor was submitted in November 2000 to the Nanoscience NIRT program, but was unsuccessful. The reviewers stated that a weakness was the lack of sufficient chemical and biological data on sensor operation. In this SGER proposal, the PI requests the funds to support a student and travel to obtain measurements of the sensor for different DNA molecules and reference solutions. These results would be used to justify further research and large funding programs.