Radiative properties of a material is the core of thermal science and optics, which play critical roles in modern technologies, including microelectronics, energy conversion, and nanotechnology. The key to modify or enhance radiative properties is employing one-, two-, and three-dimensional (1, 2, and 3D) periodic micro/nanostructures. Since their applications are not fully uncovered and very few comprehensive studies are available, the objective of this dissertation is to explore applications of periodic micro/nanostructures with modified radiative properties in modern technologies through both numerically and experimentally investigations. Theses representative applications include the thermal control in rapid thermal processing, the design of a wavelength-selective radiator for thermophotovoltaic systems, and the nanothermal manufacturing. The theoretical foundation of the study is built on the rigorous coupled-wave analysis (RCWA) for numerical calculation of the far-field radiative properties and the electromagnetic field distribution in the near-field regime. Measurements of diffraction efficiencies are conducted on fabricated 1D and 2D periodic silicon microstructures with a laser scatterometer/diffractometer with high angular resolution. The diffraction efficiency can be employed for non-contact surface profile inspection tool because it strongly depends on structure patterns. For better temperature control during rapid thermal processing, the dissertation performs a parametric study on radiation absorption of a generic CMOS device together with its simplified nanoscale structures. The applicability of approximation models, which homogenize micro/nanostructures into a film, is also evaluated. Next, a new concept of complex gratings is proposed for actively tailoring the radiative properties and serving as a thermophotovoltaic (TPV) radiator. The radiator exhibits a wide-band and angle-independent high transverse magnetic wave emittance matching the bandgap of TPV cells so that the energy conversion efficiency can be improved. Furthermore, the nanoscale metallic slit arrays show polarization-dependant enhanced transmission and highly localized electromagnetic energy density, which hold promising potentials in nanothermal manufacturing. Three submicrometer metallic slit arrays are fabricated on top of a silicon substrate. Their spectral transmittance is measured with a Fourier-transform infrared spectrometer and largely agrees with RCWA modeling results. In short, the dissertation clearly demonstrates that precise control and tuning of radiative properties using micro/nanofabrication are not only feasible but also may have numerous technological impacts.

With the discovery of conductivity in doped polyacetylene (PA), a new era in synthetic metals has emerged by breaking the traditionally accepted view that polymers were always insulating. Conducting polymers are essentially characterized by the presence of conjugated bonding on the polymeric back bone, which facilitates the formation of polarons and bipolarons as charge carriers. Among the numerous conducting polymers synthesized to date, polypyrrole (PPy) is by far the most extensively studied because of prodigious number of applications owing to its facile polymerizability, environmental stability, high electrical conductivity, biocompatibility, and redox state dependent physico-chemical properties. Electrochemically prepared PPy is more interesting than the chemically prepared polymer because it adheres to the electrode surface and can be directly used for applications such as supercapacitors, electrochemical sensors, electromechanical actuators and drug delivery systems. In quest for improvement in quality of the device performances in the mentioned applications, micro and nano structured polymeric materials which bring in large surface area are studied. Finding a simple and efficient method of synthesis is very important for producing devices of PPy microstructures. Till date, Hard and soft template methods are the most employed methods for synthesis of these structures. Soft template based electrochemical methods are better than hard template methods to grow clean PPy microstructures on electrode substrates as procedures for removal of hard templates after the growth of microstructures are very complex. As per the literature, there is no unique method available to grow PPy microstructures which can demonstrate several applications. Although gas bubble based soft template methods are exploited to grow conducting polymer microstructures of sizes in few hundreds of micrometers, studies on applications of the same are limited. Hence it is planned to develop procedures to grow microstructures that can be used in several applications. In the current work, PPy microstructures with high coverage densities are synthesized on various electrode substrates by soft template based electrochemical techniques. Hollow, hemispherical and spherical PPy microstructures are developed by a two step method using electro generated hydrogen bubble templates on SS 304 electrodes. In the first step, Hydrogen bubbles are electro generated and stabilized on the electrode in the presence of β- naphthalene sulfonic acid (β-NSA). In the second step, Pyrrole is oxidised over the bubble template to form PPy microstructures. Microstructures (open and closed cups) of average size 15 μm are uniformly spread on the surface with a coverage density of 2.5×105 units /cm2. Globular PPy microstructures are developed by a single step method using concomitantly electro generated oxygen bubble templates on SS 304 electrodes during electropolymerization. Microstructures of average size 4 μm are uniformly spread on the surface with a coverage density of 7×105 units/cm2. Surfactant properties of Zwitterionic 4-(2-hydroxyethyl)-1-piperazine ethane sulfonic acid (HEPES) are exploited for the first time to grow conducting polymer microstructures. Ramekin shaped PPy microstructures are developed using HEPES as the surfactant to stabilize hydrogen bubble templates in a two step electrochemical synthesis method. Microramekins of size 100 µm are uniformly spread on the surface with a coverage density of 3000 units/cm2. Micropipettes and microhorns of PPy are synthesised by a single step electrochemical route using HEPES as a surfactant. Hollow micropipettes of length 7 µm with an opening of 200 nm at the top of the structure are observed. Similarly microhorn/celia structures are observed with length 10-15 µm. Microcelia are uniformly distributed over the surface with each structure having a diameter of 2 µm at the base to 150 nm at the tip. Growth mechanism based on contact angle of the reactant solution droplets on the substrate is proposed. PPy microstructures are characterized by scanning electron microscopy, X-Ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman Spectroscopy and UV-Visible spectroscopy to study morphology, ‘chemical bonding and structure’ , ‘defects and charge carriers’. Applicability of the electrodes with PPy microstructures in supercapacitors is investigated by cyclic voltammetry, chronopotentiometry and electrical impedance spectroscopy. Electrodes developed by all the above methods demonstrated very good supercapacitance properties. Supercapacitor studies revealed very high specific capacitances (580, 915, 728 and 922 F/g,) and specific powers (20, 25, 13.89 and 15.91 kW/kg) for electrodes with PPy microstructures (H2 bubble based two step method, O2 bubble based single step method, HEPES stabilized H2 bubbble method and HEPES based microhorn/celia structures respectively). Supercapacitive behavior of all the electrodes is retained even after an extended charge-discharge cycling in excess of 1500 cycles. Horseradish peroxidase entrapped, bowl shaped PPy microstructures are developed for H2O2 biosensing. Amperometric biosensor has a performance comparable to the sensors reported in the literature with high sensitivity value of 12.8 μA/(cm2.mM) in the range 1.0 mM to 10 mM. Glucose oxidase entrapped PPy amperometric biosensor is developed for Glucose sensing. Sensitivity of 1.29 mA/(cm2.mM) is observed for β-D-Glucose sensing in the 0.1 mM to 5.0 mM range while 58 μA/(cm2.mM) is observed in the 5.0 to 40 mM range. Potentiometric urea sensor with urease entrapped PPy microstructures on SS electrode is developed. It is able to sense urea in the micromolar ranges down to 0.1 μM. It represented an excellent performance with sensitivity of 27 mV/decade. Sensitivity in the micromolar range is 4.9 mV/(μM.cm2). Drug encapsulation and delivery is successfully demonstrated by two actuation means (i) by electrochemical actuation, (ii) by actuation based on pH changes. Concepts are proved by delivering a fluorescent dye into neutral and acidic solutions. Drug delivery is confirmed by UV-Visible spectroscopy and Fluorescence microscopy. Finally, Micro/nanostructures with Tangerine, Hollow globular (Pani Poori), Chip, Flake, Rose, Worm, Horn and Celia shapes are synthesized electrochemically and scanning electron microscopic studies are presented. Controlled growth of microstructures on lithographically patterned gold interdigital electrodes is demonstrated with a future goal of creating addressable microstructures. The studies reported in the thesis provide an insight on various applications of PPy microstructures (supercapacitors, sensors and drug delivery systems) developed by a unique methodology based on electrochemically generated gas bubble templates.