Microslots : scalable electromagnetic instrumentation

Abstract

This thesis explores spin manipulation, fabrication techniques and boundary conditions of electromagnetism to bridge the macroscopic and microscopic worlds of biology, chemistry and electronics. This work is centered around the design of a novel electromagnetic device scalable from centimeters to micrometers called a microslot. By creating a small slot in a planarized waveguide called a microstrip, the boundary conditions of the system force an electromagnetic wave to create a concentrated magnetic field around the slot that can be used to detect or produce magnetic fields. By constructing suitable boundary conditions, a detector of electric fields can be produced as well. One of the most important applications of this technology is for Nuclear Magnetic Resonance (NMR). As demonstrated experimentally in this thesis, microslots improves the mass-limited detectability of NMR by orders of magnitude over conventional technology and may move us closer to the dream of NMR on a chip.

(cont.) Improving sensitivity in NMR may lead to a dramatic increase in the rate and accessibility of protein structural information accumulation and a host of other applications for fundamental understanding of biology and biomedical applications, and micro/macroscopic engineering. This microslot structure was constructed at both 6.9mm and 297 [mu]m in order to understand the properties as a function of scale. The 297 [mu]m structure has the best signal to noise ratio of any published planar detector and promises to have higher sensitivity with decreasing size. The detector has been used to analyze water and a relatively simple organic molecule with nanomole sensitivity. 940 picomoles of a small peptide was analyzed and a 2D correlation spectra was obtained which allowed identification of the amino acids in the peptide and could be further used to determine structure. This 297 [mu]m microslot probe was constructed using conventional printed circuit board fabrication and a laser micromachining center. A homebuilt probe was made to house the circuit board. Since this geometry is simpler than previously demonstrated techniques, fabrication can be automated for arrays and is inherently scalable to small sizes (less than 10 [mu]m).

(cont.) The planar nature of the device makes it ideal for integration with microfluidics, transceivers and applications such as cell/neuron chemistry, protein arrays, and HPLC-NMR on pico to nanomoles of sample. Furthermore, this work suggests that a physically scalable, near-field device may have a variety of further uses in integrated circuit chip diagnosis, spintronic devices, nanomanipulation, and magnetic/electric field imaging of surfaces.