Small-Scale Liquid-State Dynamics in Nanometer Size Devices

Citation

Barsic, David Nicholas (2004) Small-Scale Liquid-State Dynamics in Nanometer Size Devices. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BWJB-7K61. https://resolver.caltech.edu/CaltechETD:etd-12122003-110405

Abstract

This dissertation will present research on state-of-the-art micrometer- and nanometer-scale machining techniques to fabricate fluid channels with integral sensing electrodes. The motivation for this project is to create new instruments for investigating the behavior and properties of particles or molecules in solution and confined in a fluid channel with cross-sectional dimensions ranging from less than 50 nanometers to one micron.

The objective of this research is to develop techniques for building fluid analysis systems which combine fluid channels with sensing electrodes. Design of physical devices and the measurement circuit are both important steps in accomplishing this task. The design issues necessary for optimizing these aspects are investigated in detail. The size scale of these systems is at the lower limit achievable with current technology. Such devices require critical dimensions of less than 100 nanometers in order to perform measurements on small-scale fluid systems. Applications of this type of system include detection of both the presence and the motion of particles and molecules suspended in the small volume of fluid confined within the fluid channel. The motion of particles in the fluid channel is detected by measuring the change in electrode capacitance as particles move past the electrodes. Typical fluid volumes used in this type of system range from 50 femtoliters to less than one femtoliter.

Accomplishing this task required a careful look at the machining techniques for making microscopic devices. The approach is to use lithographic and circuit manufacturing techniques to make small fluid channels on either side of which are sets of electrodes. Existing techniques for making small-scale devices were modified to provide the required performance. In some cases the development of entirely new techniques was necessary.

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