| A unique molecular scale gap (30nm and 50nm) structure was designed, developed, and fabricated using micro- and nanomachining techniques. This molecular gap structure was created for investigating interactions between bio-molecules. The basic structure is highly manufacturable and shows an excellent yield (more than 80%). For the performance tests of the basic device, AC and DC measurements were used and the device showed a high sensitivity distinguishing different kinds of solvents and concentrations of buffer solution. In addition, it is very robust in a high electric field environment, and can tolerate about 5.6 × 106 V/cm of electric field in air when Pt electrodes are used.; The basic device structure can cover a wide range of applications by using different monolayers of self assembled molecules on the electrode surfaces. In this thesis, the basic device electrodes were modified using self-assembly to allow the device to function as a target DNA detection sensor or as a protein detection sensor. For the target DNA detection, the detection process was monitored using AC measurements, and presence of the DNA was observed in low frequency conditions (less than 50KHz), taking advantage of the sensitive measurements enabled by the nanoscale gap structure. The DNA monolayer formed on electrode surface was also checked using a unique method (monitoring of electrical resistance of the device and controlled DI water rinsing), and the ability for DNA to retain salt ions was exploited to detect the presence of DNA. For protein detection, a new detection technique using device break down in a high DC bias condition and in the presence of protein coated nanoparticles was introduced. For this protein detection approach, the molecular scale gap structure showed its unique dimensional advantages. The similar size ranges of the structure and protein carrying nanoparticles provided very sensitive device break down results. |
