A Survey on Modulation Techniques in Molecular Communication via Diffusion

This survey paper focuses on modulation aspects of molecular communication, an emerging field focused on building biologically-inspired systems that embed data within chemical signals. The primary challenges in designing these systems are how to encode and modulate information onto chemical signals, and how to design a receiver that can detect and decode the information from the corrupted chemical signal observed at the destination. In this paper, we focus on modulation design for molecular communication via diffusion systems. In these systems, chemical signals are transported using diffusion, possibly assisted by flow, from the transmitter to the receiver. This tutorial presents recent advancements in modulation and demodulation schemes for molecular communication via diffusion. We compare five different modulation types: concentration-based, type-based, timing-based, spatial, and higher-order modulation techniques. The end-to-end system designs for each modulation scheme are presented. In addition, the key metrics used in the literature to evaluate the performance of these techniques are also presented. Finally, we provide a numerical bit error rate comparison of prominent modulation techniques using analytical models. We close the tutorial with a discussion of key open issues and future research directions for design of molecular communication via diffusion systems.Comment: Preprint of the accepted manuscript for publication in IEEE Surveys and Tutorial

Optical trapping: optical interferometric metrology and nanophotonics

The two main themes in this thesis are the implementation of interference methods with optically trapped particles for measurements of position and optical phase (optical interferometric metrology) and the optical manipulation of nanoparticles for studies in the assembly of nanostructures, nanoscale heating and nonlinear optics (nanophotonics). The first part of the thesis (chapter 1, 2) provides an introductory overview to optical trapping and describes the basic experimental instrument used in the thesis respectively. The second part of the thesis (chapters 3 to 5) investigates the use of optical interferometric patterns of the diffracting light fields from optically trapped microparticles for three types of measurements: calibrating particle positions in an optical trap, determining the stiffness of an optical trap and measuring the change in phase or coherence of a given light field. The third part of the thesis (chapters 6 to 8) studies the interactions between optical traps and nanoparticles in three separate experiments: the optical manipulation of dielectric enhanced semiconductor nanoparticles, heating of optically trapped gold nanoparticles and collective optical response from an ensemble of optically trapped dielectric nanoparticles

Development and application of evanescent wave cavity ring-down spectroscopy as a probe of biologically relevant interfaces

The application of a hybrid instrument combining Evanescent Wave Cavity Ring-Down Spectroscopy (EW-CRDS) with electrochemical and fluidic methods is described. The electrochemical/fluidic methods were used to induce a surface process, the effects of which were subsequently monitored in situ and in real time with exquisite spectral sensitivity and excellent temporal resolution by EW-CRDS. The well-defined manner in which the surface processes were initiated allowed the extraction of kinetic rate constants by fitting the EW-CRDS data to mathematical models of the surface process coupled to convection-diffusion. The investigations described include: the study of the thermodynamics and kinetics of the adsorption of tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+) to polypeptide films using EW-CRDS with chronoamperometry; the real-time electrochemistry of cytochrome c immobilised on silica by EW-CRDS with chronoamperometry; the kinetics of adsorption and DNA-assisted desorption of 5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrin at the silica-water interface using EW-CRDS with an impinging jet flow cell; and the monitoring the adsorption of cationic phospholipid vesicles at the silica-aqueous interface and the interaction of 5,10,15,20-Tetraphenyl-21H, 23H-porphine-p,p′,p″,p′′′-tetrasulfonic acid tetrasodium hydrate with the resulting bilayer also using EW-CRDS with an impinging jet flow cell. The work described in this thesis provides a platform on which EW-CRDS can be used to study dynamics at biointerfaces, such as the association of ions, peptides, proteins and drugs with phospholipid bilayers, the electron transfer between redox enzymes in a biomimetic environment, and the lateral diffusion of protons, ions and proteins at biomembranes. Such studies are essential to the understanding of many important cellular processes in addition to the development and optimisation of a number of bio-inspired technologies

Development and application of evanescent wave cavity ring-down spectroscopy as a probe of biologically relevant interfaces

The application of a hybrid instrument combining Evanescent Wave Cavity Ring-Down Spectroscopy (EW-CRDS) with electrochemical and fluidic methods is described. The electrochemical/fluidic methods were used to induce a surface process, the effects of which were subsequently monitored in situ and in real time with exquisite spectral sensitivity and excellent temporal resolution by EW-CRDS. The well-defined manner in which the surface processes were initiated allowed the extraction of kinetic rate constants by fitting the EW-CRDS data to mathematical models of the surface process coupled to convection-diffusion. The investigations described include: the study of the thermodynamics and kinetics of the adsorption of tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+) to polypeptide films using EW-CRDS with chronoamperometry; the real-time electrochemistry of cytochrome c immobilised on silica by EW-CRDS with chronoamperometry; the kinetics of adsorption and DNA-assisted desorption of 5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrin at the silica-water interface using EW-CRDS with an impinging jet flow cell; and the monitoring the adsorption of cationic phospholipid vesicles at the silica-aqueous interface and the interaction of 5,10,15,20-Tetraphenyl-21H, 23H-porphine-p,p′,p″,p′′′-tetrasulfonic acid tetrasodium hydrate with the resulting bilayer also using EW-CRDS with an impinging jet flow cell. The work described in this thesis provides a platform on which EW-CRDS can be used to study dynamics at biointerfaces, such as the association of ions, peptides, proteins and drugs with phospholipid bilayers, the electron transfer between redox enzymes in a biomimetic environment, and the lateral diffusion of protons, ions and proteins at biomembranes. Such studies are essential to the understanding of many important cellular processes in addition to the development and optimisation of a number of bio-inspired technologies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Can Hydrodynamic Electrons Exist in a Metal? A Case Study of the Delafossite Metals PdCoO2 and PtCoO2

In an electron fluid, both resistive and viscous mechanisms can be present. In systems with perfect translational invariance momentum is a conserved quantity, and as the electrons carry both charge and momentum, the current cannot decay. Predictions from theories at the particle physics-condensed matter physics interface using the `AdS/CFT' correspondence suggest that hydrodynamic charge flow might exist in some exotic metallic states. In the high-Tc cuprates the T-linear resistivity in the strange metal regime is conjectured to be due to hydrodynamic effects. In this dissertation, I start out drawing a theoretical outline of the hydrodynamic theory of electron transport in solids. In the search for a high purity metal that can host such a hydrodynamic electron transport, we looked at the non-magnetic delafossite oxides PdCoO2 and PtCoO2, which have the highest conductivities of any known oxides, and whose key properties I will review. As the signatures of viscosity can only be realised in transport through boundary scattering, the samples had to be taken down to the mesoscopic limit, where the momentum conserving and relaxing scattering mean free paths of the material are comparable to the channel width. I will discuss the focussed ion beam (FIB) micro-structuring technique that I have implemented to fabricate the mesoscopic devices. To interpret the transport in the mesoscopic regime, a comprehensive understanding of the bulk transport is first necessary and I will present my measurements of the magnetoresistance and Hall effect in both materials, which show deviations from the predictions of standard models highlighting some intriguing physics even in the bulk limit. Finally, I will present the data from magnetotransport measurements at the mesoscopic limit. Magnetic field introduces a variable length scale, the cyclotron radius, in the system which can be used to tune through different transport regimes. I will discuss the ballistic and hydrodynamic signatures in the transport that becomes accessible through magnetic field tuning in the mesoscopic samples of the delafossites PdCoO2 and PdCoO2

Free-Space Diffraction Effects in an All Optical Passive Driven System

Physic

High-Energy-Density Physics Experiments of Rayleigh-Taylor Instability Growth at Low-Density-Contrast

This dissertation describes experiments performed at the Omega-60 laser facility to investigate the nonlinear growth stage of the Rayleigh-Taylor instability (RTI) at a low-density-contrast embedded interface initialized with 2D and 3D single-mode sinusoidal perturbations. RTI occurs at the interface between two fluids of different densities when the lower-density fluid pushes the higher-density fluid. Such a system is energetically unstable: a small-amplitude perturbation at the interface evolves into features described as "bubbles" (parcels of light-fluid rising upward) and "spikes" (regions of heavy-fluid falling downward). Bubbles and spikes interpenetrate across the interface, forming a mixed-fluid region which continues to grow, thereby lowering the potential energy of system. This fundamental hydrodynamic instability is encountered throughout nature and engineered systems. In the realm of high-energy-density (HED) physics, RTI occurs in astrophysical phenomena such as supernovae explosions and in the laboratory during implosion of inertial confinement fusion (ICF) capsules. The ability to model and predict the evolution of RTI has important consequences for fundamental scientific understanding and engineering applications. Theoretical approaches to RTI consider three separate cases: single-mode, multi-mode, and turbulent mixing, which evolve differently. Analytical models successfully predict macroscopic growth rates of the mixed-fluid layer for these three cases under certain conditions, but neglect the small-scale mixing dynamics, which are essential to describing transitional states. To develop reliable predictive capabilities, we must understand how the seed spectrum, density contrast of the two fluids, miscibility, acceleration history, and Reynolds number affect the evolution of RTI. Experiments with well-controlled initial conditions enable us to isolate and study particular aspects of the problem. Recent classical fluids experiments and numerical simulations investigate the late-nonlinear growth stage of single-mode RTI and dependence on density contrast. At low-density-contrast, single-mode RTI growth appears to reaccelerate, beyond the terminal velocity predicted by potential-flow models. In the late-nonlinear stage, secondary instabilities arise which modify the internal mixing dynamics and growth rate. No existing models describe this stage of RTI growth, where the mixed-fluid region is partially coherent, partially chaotic, but not fully turbulent. The work presented here investigates this regime in a high-energy-density system relevant to astrophysics and ICF. In this dissertation, I describe experiments performed at Omega-60, a 10-kJ-class laser facility. In this experimental platform, a blast wave drives RTI growth at an embedded interface inside a shock tube. Using dual-axis X-ray radiography, we observed the evolution of the mixed-fluid region from 17-47 ns. Experimentally measured spike- and bubble-front positions are compared with buoyancy-drag models and radiation-hydrodynamics simulations. The experiments at Omega-60 did not sustain acceleration for long enough to drive RTI into the desired regime, but provided valuable information to inform the design of future experiments at the National Ignition Facility, a MJ-class laser facility.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/153442/1/lelgin_1.pd