Electrical detection of bio-molecular interactions using nanometer-scale gap electrode structures

by Cuffi, Joseph Dennis.

iii Detecting biological molecules faster and with greater sensitivity has immediate impact on medicine and healthcare. Disease identification and drug development rely on the ability to detect and identify biological chemicals and their interactions. Currently, most detection techniques rely on optical methods such as a color change to determine the presence of a biological compound. The ability to perform these tests electrically has the potential for faster and more sensitive results and the ability to couple easily with computer analysis. A unique sensor device and technique for detecting biological molecules has been developed. Here, an electrical sensor with nanometer-scale dimensions is made using standard processes and equipment found in the semiconductor industry. This sensor has the ability to be chemically modified to detect specific biological compounds. This is the first time a device combining these properties effectively for commercial use has been presented. Processes used in the fabrication of the device are shown to be critical in preserving the ability for chemical modification as a sensor. A unique chemical linking method has also been developed which allows effective biological modification of the device. This modification of the device allows for specific biological molecules to interact with surfaces of the device. The modification can be used to tailor the device to interact with a range of biological molecules including DNA, proteins and other small bio-molecules. The ability of the chemistry to interact with a variety of different species is important iv for commercialization, because a versatile platform is more economically viable to develop. Using an example system, this device electrically detected the interaction of two biological molecules. The detection scheme makes the use of biologically modified gold nano-particles, which change the electrical characteristics of the device. The sensitivity of the device is among the highest reported for electrical techniques, and the technique itself appears robust enough for commercial development. Overall, this unique and cost-effective sensor offers sensitive detection of biological molecules.