Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 167-184). / T cells are required by their immunological roles to recirculate in the body and migrate to tissue sites, a journey that exposes them to distorting forces and physical obstacles that hinder their movement. Therefore, they must possess appropriate deformability to accommodate and adapt to these mechanical stimuli to migrate unimpeded. Since T cells alter their physical properties and migration routes upon activation, they may possess dissimilar mechanical properties as a result of this process. This hypothesis was tested using the techniques micropipette aspiration and atomic force microscopy, which allow the investigation of the elastic and viscous responses of single T cells. It was discovered that the activation process reduced T cell stiffness by more than three folds, a finding that agrees with the motility gain observed in activated T cells. The same testing procedure was applied to Wiskott-Aldrich syndrome protein (WASp)-deficient T cells that exhibit abnormal morphology and impaired chemotaxis. The stiffness of the diseased cells in the naive state was 1.5 times less than that of the non-diseased cells, a result that may be due to the disrupted polymerization and cross-linking of the actin cytoskeleton in the absence of WASp, a regulator of actin growth and organization. Furthermore, the viscous response of the diseased cells in the activated state was found to be impaired. Chemokines were found to dramatically reduce the stiffness of naive T cells that were induced to migrate. These findings suggest that WASp plays an important role in maintaining cell mechanical property and facilitating T cell extravasation by tailoring the cells' deformability. At the molecular level, activation of T cells is triggered by the binding of their surface receptors to antigens, a mechanism that is also key in T cell development. In both cases, the bond strength, conventionally measured by the affinity (KD) or the dissociation rate (koff) of the interacting pair, dictates the biological outcome. Since a few weak interactions may nudge a sub-threshold signal over the threshold strength, and observing that the current methods for measuring KD and koff lack the resolution to detect very weak bonds, this work explored the possibility of utilizing dynamic force spectroscopy (DFS) to study very weak binding strengths. Preliminary results confirm this capability. / by Irene Yin-Ting Chang. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / Includes bibliographical references (p. 191-204). / by Gerardo Damián Garbulsky. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 47-48. / by James Forrest Kirk. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2005. / Includes bibliographical references (p. 147-158). / Monolithic integration has been implemented successfully in complementary metal oxide semiconductor (CMOS) technology and led to improved device performance, increased reliability, and overall cost reduction. The next element to be incorporated on the silicon chip is the power unit; possibly as part of the back end process of the very large scale integrated (VLSI) circuits' production. This thesis describes the work done in developing and studying thin film integrated lithium ion batteries compatible with microelectronics with respect to the material system employed, the cells' fabrication methods, and performance. The project consisted of three stages; first, a material system new to the battery application field was explored and power cells were fabricated and characterized. In the second stage, the fabrication process of the first material system cells was optimized thereby improving their performance. The third stage dealt with a more conventional battery material system, utilizing thin film technology to fabricate and explore power cells. / (cont.) All the cells fabricated in this work were created using microelectronic technology and were characterized by thin film analysis techniques and by measurement equipment commonly used for microelectronic device testing. The cells were fabricated in four sizes of active areas: 5x5 mm², 2x2 mm², lxl mm², and 0.5x0.5 mm². The first material system consisted of a novel lithium-free electrolyte in the form of an ultra-thin SiO₂ layer, thermally grown from sacrificial polysilicon layer on a doped polysilicon anode. The concept of SiO₂ as an electrolyte is innovative since common solid state lithium and lithium ion batteries consist of 1-2 ptm thick lithium-containing electrolytes. The controlled transport of lithium through SiO₂, 9-40 nm thick, was studied for electrolyte application. The fabricated LiCoO₂/SiO₂/polysilicon cells were successfully charged and discharged. This stage of the project demonstrated the concept of an ultra-thin lithium free electrolyte layer and introduces SiO₂ as an interesting candidate material. The second stage of the project focused on improving the LiCoO₂/SiO₂/polysilicon cell's performance and optimizing its fabrication process. / (cont.) Chemical mechanical polishing (CMP), a typical planarization method in microelectronics, new to the battery application field, was introduced in order to enhance the cell's properties and performance. LiCoO₂/SiO₂/polysilicon cells consisting of Si0₂ layers 7-40 nm thick were studied. Cells with the planarized polysilicon anode were characterized and the planarization effect was evaluated. This stage demonstrates the importance of interfacial quality in thin film batteries and the advantages incorporation of CMP as a planarization step in the fabrication process. Finally, the third stage of the project focused on applying the thin film technology knowledge and expertise to a more commonly used material system V₂0₅/LiPON/LiCoO₂. With the aim of reducing interfacial roughness, a surface morphology study of V₂0₅ was performed, tailoring different deposition conditions and surface morphology. Implementing the optimized conditions obtained from this analysis, a V₂0₅/LiPON/LiCoO₂ rocking-chair battery was studied next. The cells consisted of approximately 100 or 350 nm thick lithium phosphorus oxynitride (LiPON) electrolyte. / (cont.) This stage demonstrated the advantage of thin film technology in reducing film thickness and the performance enhancement achieved. The work described in this thesis approached the thin film battery subject from the microelectronic perspective, in order to "bring the battery into the clean room". / by Nava Ariel. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 207-225). / Polyelectrolyte multilayers (PEMs) are a versatile type of thin film that is created via layer-by-layer assembly of positively and negatively charged polymers from aqueous solutions. Precise control of the PEM thickness, chemical functionality, and molecular architecture is made possible by changing the polyelectrolytes and assembly conditions during film growth, allowing films to be designed with properties suitable for a given application. This thesis elucidates the intra-film structure and interactions of PEMs through the use of optical, mechanical, and chemical techniques. PEM rugate filters, wherein the refractive index varies through the depth of the film in a continuous, periodic fashion, were constructed by confining silver nanoparticle growth to layers of nanometer-scale thickness. The ability to construct such structures is shown to be dependent on the ability to precisely control the concentration of metal-binding carboxylic acid groups throughout the depth of the film. Software to enable the computation design and optical simulation of these and similar structures was developed. / (cont.) A buckling instability technique was used to probe the Young's modulus of PEM assemblies as a function of polyelectrolyte type, assembly pH, and the relative humidity of the ambient environment. In particular, a two-plate methodology was developed to allow testing on a broad array of multilayer films, and an experimental apparatus was constructed to allow in situ modulus measurements of PEM films under controlled humidity conditions. These techniques are used to elucidate the strong effects that polyelectrolyte type, assembly pH, and the ambient humidity can have on the stiffness of PEM films. The controlled removal of material from assembled PEMs was accomplished via etching of films in solutions of increasing ionic strength. The properties of etched films and process dynamics point to evidence of a polydispersity-enabled phenomenon driven by dissolution of polyelectrolyte complexes containing chains of disproportionate molecular weight. Kinetic and equilibrium data are presented that support this hypothesis. Beyond elucidation of the underlying mechanisms governing molecular interactions within PEMs, possible practical applications for the particular PEM assemblies described in this thesis are discussed, including conformable interference filters and buckling-enabled patterning. / by Adam John Nolte. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / Includes bibliographical references (leaves 79-80). / by Corey J. Foster. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, February 2004. / Includes bibliographical references (p. 200-215). / The first step in two of the most troublesome biological responses to the implantation of blood-contacting biomaterials, i.e. thrombosis and inflammation, is the adhesion of blood plasma proteins to the biomaterial surface, which may then initiate platelet adhesion and activation, and thereby set in motion a cascade of adverse host responses. If devices could be developed that prevent that first step from occurring altogether, a new generation of "stealth" biomaterials would be born. Such was the motivation of this project, which sought to investigate the constituent intermolecular interaction forces governing protein adhesion to biomaterials, using the technique of high resolution force spectroscopy. The model protein chosen for our study was human serum albumin (HSA), the smallest and most abundant blood protein in the human body, and typically the first to adsorb to a blood-contacting, implanted device. In the first stage of our investigation, HSA was covalently grafted to a nanosized probe tip at the end of a soft, microfabricated cantilever force transducer. The intermolecular interaction potential, U(D), was recorded between the HSA-modified probe tip and four different model surfaces, including: 1) gold, 2) a hydrophobic, CH3-terminated alkanethiol self-assembling monolayer (SAM), 3) a hydrophilic, COO-terminated alkanethiol SAM, and 4) individual, covalently end-grafted molecules of poly(ethylene oxide), in aqueous sodium phosphate buffer solution (PBS, ionic strength IS = 0.01M, pH = 7.4). Both theoretical and numerical modeling were employed to evaluate the experimental results on each of the different surfaces, and to characterize the nature of the protein-bound probe tip. In the second part of this study, / (cont.) we aimed to elucidate the various constituent intermolecular interaction forces contributing to U(D) by strategically manipulating experimental conditions such that we were able to isolate, and in some cases quantify, the electrostatic, steric, and hydrophobic components. It was found theoretically that electrostatic and steric forces accounted for approximately 8% and 4% of the total intermolecular interaction force; experimentally, these forces are observed to be completely dominated by a repulsive force which increases in magnitude as the ionic strength of the solution is increased. It is believed that this additional force is imparted by the PEO, and may be due to a change in the conformation of the PEO coil, or the structure of the network of water molecules in the space between the PEO coil and the approaching probe tip. The hydrophobic component was experimentally quantified to be approximately 20% of the total intermolecular interaction force at D [approx.] 1 nm. In the third part of this investigation, we sought to study the interactions between HSA and a series of oligosaccharide-functionalized surfaces inspired by the glycocalyx, which coats all living cells and is naturally and necessarily hemocompatible. The results of this study were then compared to experiments conducted in parallel on poly- and oligo(ethylene oxide) modified surfaces. Our results suggest that higher oligosaccharides ... / by Monica Ann Rixman. / Ph.D.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007. / Includes bibliographical references. / The discovery of high brightness (white) light emitting diode (LED) is considered as a real threat to the current lighting industry in various applications. One of the most promising sectors would be using white LED to replace the current Cold Cathode Fluorescent Light (CCFL) technology as the backlight of the large screen Liquid Crystal Display (LCD) screen due to the fact that LCD is a rapidly booming market. / by Chian Myau Soon. / M.Eng.

Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, June 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (page 35). / Thin film BCZT was processed, optimized, and analyzed from powder to ceramic to film for use in a capacitive thermos-electric converter. The idea of using a temperature dependent dielectric to turn heat into electricity has been around for several decades but has never been feasible due to low efficiency and the practical difficulty of being able to thermally cycle the dielectric material quickly enough. However, thin film materials are able to be thermally cycled at high enough frequencies. One material that has potential to be used as the dielectric in a capacitive thermo-electric converter is Ba(TixZr1-x)O3-(BayCa1-y)TiO3. Known as BCZT, this perovskite has previously been studied as an alternative to piezo electrics which are traditionally made with lead. BCZT has a very high dielectric constant of several thousand and, because of its triple point just above room temperature, the dielectric constant is temperature dependent around room temperature. In this paper, BCZT is studied for its potential as a thin film dielectric material in a capacitive thermo-electric converter. Several different compositions around the triple point are created from powder sources, sintered into targets for PLD, analyzed, and the most promising composition was deposited into a thin film and patterned with in-plane capacitor contacts. Analysis using XRD and dielectric measurements was done at several stages. / by Emily Thomson. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008. / Includes bibliographical references (p. 39-43). / A novel processing method was developed for sub-50 nm structures by integrating quantum dots (QDs) on patterned polymer substrates. Poly(styrene-alt-maleic anhydride) (PSMa) was prepared by the initiated chemical vapor deposition (iCVD) method, an alternative to spin-on deposition. The sub-50 nm PSMa polymer patterns were prepared by low energy oxygen plasma etching by using CNTs as the masks. The water soluble, amine-functionalized QDs underwent the nucleophilic acyl substitution reaction with the PSMa containing anhydride functional groups. This integration method is use to incorporate high performance QDs on inexpensive, lightweight flexible substrate. / by Chia-Hua Lee. / S.M.