Fundamental Tests of Physics with Optically Trapped Microspheres details experiments on studying the Brownian motion of an optically trapped microsphere with ultrahigh resolution and the cooling of its motion towards the quantum ground state. Glass microspheres were trapped in water, air, and vacuum with optical tweezers; and a detection system that can monitor the position of a trapped microsphere with Angstrom spatial resolution and microsecond temporal resolution was developed to study the Brownian motion of a trapped microsphere in air over a wide range of pressures. The instantaneous velocity of a Brownian particle, in particular, was studied for the very first time, and the results provide direct verification of the Maxwell-Boltzmann velocity distribution and the energy equipartition theorem for a Brownian particle. For short time scales, the ballistic regime of Brownian motion is observed, in contrast to the usual diffusive regime. In vacuum, active feedback is used to cool the center-of-mass motion of an optically trapped microsphere from room temperature to a minimum temperature of about 1.5 mK. This is an important step toward studying the quantum behaviors of a macroscopic particle trapped in vacuum.

This thesis makes significant advances in the use of microspheres in optical traps as highly precise sensing platforms. While optically trapped microspheres have recently proven their dominance in aqueous and vacuum environments, achieving state-of-the-art measurements of miniscule forces and torques, their sensitivity to perturbations in air has remained relatively unexplored. This thesis shows that, by uniquely operating in air and measuring its thermally-fluctuating instantaneous velocity, an optically trapped microsphere is an ultra-sensitive probe of both mass and sound. The mass of the microsphere is determined with similar accuracy to competitive methods but in a fraction of the measurement time and all while maintaining thermal equilibrium, unlike alternative methods. As an acoustic transducer, the air-based microsphere is uniquely sensitive to the velocity of sound, as opposed to the pressure measured by a traditional microphone. By comparison to state-of-the-art commercially-available velocity and pressure sensors, including the world’s smallest measurement microphone, the microsphere sensing modality is shown to be both accurate and to have superior sensitivity at high frequencies. Applications for such high-frequency acoustic sensing include dosage monitoring in proton therapy for cancer and event discrimination in bubble chamber searches for dark matter. In addition to reporting these scientific results, the thesis is pedagogically organized to present the relevant history, theory, and technology in a straightforward way.

Fundamentals and Applications of Nano Silicon in Plasmonics and Fullerines: Current and Future Trends addresses current and future trends in the application and commercialization of nanosilicon. The book presents current, innovative and prospective applications and products based on nanosilicon and their binary system in the fields of energy harvesting and storage, lighting (solar cells and nano-capacitor and fuel cell devices and nanoLEDs), electronics (nanotransistors and nanomemory, quantum computing, photodetectors for space applications; biomedicine (substance detection, plasmonic treatment of disease, skin and hair care, implantable glucose sensor, capsules for drug delivery and underground water and oil exploration), and art (glass and pottery). Moreover, the book includes material on the use of advanced laser and proximal probes for imaging and manipulation of nanoparticles and atoms. In addition, coverage is given to carbon and how it contrasts and integrates with silicon with additional related applications. This is a valuable resource to all those seeking to learn more about the commercialization of nanosilicon, and to researchers wanting to learn more about emerging nanosilicon applications. Features a variety of designs and operation of nano-devices, helping engineers to make the best use of nanosilicon Contains underlying principles of how nanomaterials work and the variety of applications they provide, giving those new to nanosilicon a fundamental understanding Assesses the viability of various nanoslicon devices for mass production and commercialization, thereby providing an important source of information for engineers

This book highlights cutting-edge research in surface plasmons, discussing the different types and providing a comprehensive overview of their applications. Surface plasmons (SPs) receive special attention in nanoscience and nanotechnology due to their unique optical, electrical, magnetic, and catalytic properties when operating at the nanoscale. The excitation of SPs in metal nanostructures enables the manipulation of light beyond the diffraction limit, which can be utilized for enhancing and tailoring light-matter interactions and developing ultra-compact high-performance nanophotonic devices for various applications. With clear and understandable illustrations, tables, and descriptions, this book provides physicists, materials scientists, chemists, engineers, and their students with a fundamental understanding of surface plasmons and device applications as a basis for future developments.

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome.

This thesis reports on the development of the first quantum enhanced microscope and on its applications in biological microscopy. The first quantum particle-tracking microscope, described in detail here, represents a pioneering advance in quantum microscopy, which is shown to be a powerful and relevant technique for future applications in science and medicine. The microscope is used to perform the first quantum-enhanced biological measurements -- a central and long-standing goal in the field of quantum measurement. Sub diffraction-limited quantum imaging is achieved, also for the first time, with a scanning probe imaging configuration allowing 10-nanometer resolution.

Cells are the basic unit of living organisms and consist of a cytoplasm, which is enclosed by a membrane. As building blocks of life with a plethora of functions, cells have to be equipped with a high degree of mechanical resistance, durability, and variability. In eukaryotic cells three filamentous protein types – actin filaments, microtubules, and intermediate filaments (IFs) – form the so-called cytoskeleton, a network that is known to play a key role for the mechanical properties of cells. Among the three filament systems, IFs are special in terms of, for example, their hierarchical architecture, and their cell-type specific expression. In this thesis, vimentin, an IF mostly found in mesenchymal cells, is studied as a model system to learn more about the mechanical properties of IFs, and the underlying mechanisms that determine their robustness, stiffness, and flexibility. Using a combination of optical trapping and atomic force microcopy experiments and stochastic and numerical modelling, vimentin is found to possess impressive physical properties, such as an extendibility of about 3.6 times its initial length and a tensile memory that can be directly linked to the molecular architecture of the protein and the hierarchical construction of the filament. The experimental results show a clear loading-rate- and strain-dependent behavior of single vimentin IFs supporting the hypothesis that vimentin acts as a “safety belt” for cells, protecting them especially at large and fast deformations. The potential to dissipate a large amount of energy that is attributed to distinct non-equilibrium unfolding and refolding of the α-helices, which are the main structural feature of the vimentin monomer, enables vimentin to act as a shock absorber when exposed to large deformations. In case of cyclic deformations, such as in the cardiovascular system, the observed tensile memory could potentially help cells to be compliant with the repeated strain. In conclusion, vimentin is found to display highly interesting and diverse mechanical properties depending on the applied stress that could be linked to the molecular architecture of the filaments and enable vimentin to determine the mechanical properties of cells to a large extend.