| An outstanding challenge in biomedical sciences is to devise systems that can enable rapid, simultaneous and quantitative imaging of tens to hundreds of species at ultra-low concentrations. Central to addressing this challenge is the availability of a modality capable of sensitive, rapid, cost-effective and multiplexed sensing. Further, the microscopic heterogeneity of intact biological systems necessitates that the sensing be in an imaging format. Vibrational spectroscopic imaging (both Raman and infrared) is an attractive tool due to its potential to obtain rich chemical and structural information using relatively accessible instrumentation. Its applicability in devising such modality however is limited by current detection limits, throughput and speed of acquisition. This dissertation discusses design of novel nanostructured devices for enhancing the sensitivity, acquisition rate and multiplexing capabilities in vibrational spectroscopic imaging.;First, Surface-enhanced Raman scattering (SERS)-based nanostructured particle probes are proposed. Their optical tunability with structure is discussed in detail and preliminary fabrication and validation are presented. Next, design and fabrication of a new class of filters for narrow-band optical reflection in mid-infrared spectral regions using guided mode resonances is demonstrated. The design principles and methodology presented in this dissertation are expected to provide a rational approach in development of sets of probes and filters to enable rapid, ultrasensitive acquisition of unlimited number of molecular targets. |
