B.A. College of Notre Dame of Maryland 2002
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SERS nanoimaging probe
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System Schmatic
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Technological advances in the manipulation and fabrication of nanoscale systems and objects, both naturally occuring (cellular components, etc.) and man-made (nanotubes, biological circuits, polymer surfaces, etc.), have led to increased interest in the development of devices and instrumentation for the characterization of these systems. One means by which these systems can be further characterized and understood is through high-resolution chemical imaging. My project focuses on developing novel surface enhanced Raman scattering (SERS)-based nanoimaging probes for dynamic chemical imaging in a non-scanning format.
These SERS nanoimaging probes have been developed for obtaining sub-diffraction limited chemical images of various biochemical species (e.g., lipids, proteins, etc.) as well as biological organisms (e.g., bacteria, etc.). They combine qualitative and quantitative information obtained from SERS with the imaging capabilities of coherent fiber optic bundles. Nanoimaging probes are fabricated from coherent fiber optic bundles composed of 30,000 individual 4 ?m diameter fiber elements. Using a CO2 laser based micropipette puller, bundles are tapered on one end resulting in the formation of equi-diameter individual elements tens of nanometers to hundreds of nanometers in dimension. Employing these probes, inherent image magnification and submicron spatial resolution is possible. Across these tapered probe tip, uniformly roughened surface features are creating by HF acid etching. These surface features consist of six cladding peaks that surround each individual fiber elements core and they are uniform in size, shape, structure, and spacing. SERS active surfaces are created on the tapered tips of the probes by selectively depositing silver onto these cladding peaks, creating an array of highly ordered uniform silver islands across these nanoimaging probes’ surfaces. This fabrication process results in a high degree of uniformity in SERS enhancement across the image surface of the probes (< 3.0% RSD), which is key for reproducible quantitative imaging applications. Further SERS enhancement and specific excitation wavelength tuning can be achieved by controlling the spacing between silver islands and the overall size of the silver islands uniformly arrayed across these SERS probe tips.
