Every year an estimated 17 million people worldwide die of cardiovascular disease, making it responsible for one-third of all deaths. Even though vascular problems have been around for a long time there are still many factors that are not well understood. Atherosclerosis the most common form of cardiovascular disease. It is a complex biological process in which plaque gradually develops at susceptible locations in certain arteries (e.g., carotid, femoral). Plaque typically consists of a core containing lipids and cellular material separated from the blood stream by fibrous tissue (cap). Rupture of plaque tissue can lead to the formation of blood clots that often produce cardiovascular complications such as heart attacks, strokes and acute limb ischemia. Plaque development is believed to start with cholesterol deposition and foam cell formation. Further progression leads to the formation of mature plaques that often have a fibrous tissue containing smooth muscle cells, elastin, and collagen fibrils. Underneath the fibrous tissue are often softer materials containing cellular components and cholesterol crystals. The strength of fibrous cap is thought to contribute to plaque stability. Over time, bio-mineralization (calcified regions) of a plaque may occur and cholesterol crystals may penetrate into the fibrous tissue. Within prosthetic grafts, intimal hyperplasia can form fibrous tissue by a process that differs from atherosclerosis. The tissue may seriously impede blood flow. For the purposes of this dissertation, the key aspects of plaque tissue explored are the microstructural arrangement of collagen fibrils, the presence of the bio-mineral hydroxyapatite and cholesterol crystals and the use of collagen fibrils as micro strain sensors. The use of small X-ray scattering (SAXS) to characterize the orientation of collagen fibrils in human plaque tissue was explored, for what is believed to be the first time. A specimen tilting methodology was developed to find 3D collagen fibril orientation. Changes in collagen fibril orientation approaching macroscopic calcifications (millimeters in size) were observed in plaque tissue specimens from femoral and carotid arteries. In most cases, collagen fibrils were found to be oriented in the circumferential direction away from such calcifications. Spatial distribution maps of hydroxyapatite (HA) and cholesterol crystals (CC) in carotid and femoral plaque tissue specimens were obtained, for the first time. Wide angle X-ray scattering (WAXS) was shown to be suitable for that purpose. HA crystal sizes in tissue specimens were also determined and mapped. It was found that HA crystal sizes examined were comparable to sizes in bone. HA sizes within a given specimen varied by a factor of two to three in most cases and from specimen-to-specimen (patient-to-patient) by roughly 50%. Sizes were often greatest in regions of macroscopic calcification with high X-ray absorption and smaller near edges of calcifications having lower absorption. The use of SAXS to measure strains in collagen fibrils of specimens of human plaque tissue and porcine aorta was explored. Collagen fibril strains in aorta tissue were measured successfully and related to tissue-level macroscopic strains. The experiments provided useful insights in the possibility of using fibrils as microscopic "strain sensors" if changes in collagen fibril D-period can be monitored. Experimental difficulties prevented a similar assessment for plaque tissue specimens. An attempt was made for the first time to measure residual strains in cardiovascular tissue using SAXS. The results, although inconclusive, provide a starting point to spark interest in possible future work. Technology advancements have allowed for very precise measurement tools such as SAXS and WAXS to be developed, which can be utilized to help understand atherosclerotic plaque tissue. It is my hope that researchers can take what was learned in this study and continue the research further.

In a world of boundaries, silos, and division, engineers have been called to address so-called "wicked" design challenges such as energy insecurity and inequity that are ill-structured, complex, and tied to multiple groups of stakeholders and potential contributors. As engineers, we are typically untrained in facilitating meaningful engagement with people beyond our knowledge group and organizational boundaries—engaging members of other groups as design contributors, not just as design consultants or recipients of designs. This thesis works to build theory on how designers within organizations and potential design contributors within and outside those organizations span their knowledge group and organizational boundaries as they co-design together. The findings are based on inductive grounded theory analyses of ethnographic fieldwork over two-five years, some of which was collected by a team of researchers, in partnership with design firms in the energy and automotive industries. The main contributions of the thesis are twofold. Firstly, I build theory on how product development professionals engage with objects and each other to support collaborative inquiry, discovery, and design across knowledge group boundaries. Secondly, I build theory on how co-creative capacity is developed or diminished between a firm and an open online community. This work answers recent calls from within the design research community to move toward "theory-driven" research. I build directly upon theories from organization studies, namely "absorptive capacity" and "objects of collaboration." Additionally, the work contributes to a sparse but growing literature that uses a multi-year ethnographic approach with practicing engineers in design organizations in contrast to studies with students or based on surveys, interviews, or controlled experiments that provide only snapshots in time or are divorced from professional design contexts. Taken together, the findings have practical implications for how those engaged in product development can build co-creative capacity, use objects of collaboration, and engage across knowledge group and organizational boundaries to co-design a better world

The current paradigm in engineering education promotes linear, convergent thinking focused on gaining technical knowledge. Although convergent thinking is important in engineering, divergent thinking is critical to considering the context in which engineering design problems are situated and to generating innovative ideas to address those problems. This is especially true in today's professional engineering workplace where, more and more often, we are tackling engineering problems from a broader perspective in larger, more interdisciplinary teams. Engineering work requires divergent thinking skills that are not emphasized in most engineering programs. To this end, there is a growing body of research showing that a fundamental human capacity, mindfulness, fosters divergent thinking, and that mindfulness can be cultivated through practice. Mindfulness is defined as intentionally paying attention with openness, curiosity and discernment. Although psychologists continue to explore the exact mechanisms by which mindfulness facilitates divergent thinking, there is convincing evidence that there is a causal link between a mindfulness and divergent thinking ability. In the present work, I develop a conceptual framework connecting mindfulness, divergent thinking, and innovation to explore three outcomes: does mindfulness predict (1) divergent thinking in an ideation task (2) divergent thinking in an engineering problem scoping task, and (3) one's confidence in his/her ability to be innovative. This dissertation covers the methods and findings designed to answer these questions and concludes with discussion of the results and recommendations for application of this research to engineering education and engineering practice.

While the changing nature of design activity is a topic supported by a range of popular and academic publications, the role that design tools have taken in that change is less well studied. The tools used in the trade, both by industrial designers and mechanical engineers, have undergone a rapid transformation in the last fifty years. The research that has been performed on design tools has centered on technological developments. There has also been notable popular speculation on how an expanded user base might take advantage of accessible design tools. However, there have been few formal studies of how novice users, especially those outside of the professions traditionally associated with CAD and 3D printing, can learn and implement these tools. Access to CAD and a 3D printer is not enough to enable users with ideas to realize them. The users must also be taught the affordances and limitations of the tools in order to use them. The existing research on CAD education was developed primarily for engineering college students. Because the technology has only been accessible to non-engineering professionals in the last few years, it is unknown if the existing educational methods are acceptable for the wider demographic, or if they can be improved upon. This knowledge gap leads to the following research questions: -Do engineering college students and non-engineering students learn digital design tools differently? -How are students' perceived ability to learn digital design tools affected by their professional identity and confidence? -What unique challenges do teachers face in educating non-engineering students in digital design tool use? To answer these questions, a survey of existing mechanical engineering degree programs was conducted to document existing digital tool education approaches. The information gathered from institutional web-sites was paired with a set of ten in-depth interviews of digital tool education professionals to produce three models of existing education approaches. Three independent, in depth case studies were then conducted in three different learning environments: a traditional mechanical drawing/CAD class taught to engineering college students, a new CAD and 3D printing class taught to a mixed group of undergraduate and graduate college students, and a CAD and 3D printing workshop taught to a group of practicing nurses. These case studies supported the educational models proposed in the earlier program surveys and interviews, and highlighted the conflicts that arose from the models inherent assumptions about their target demographic. These conflicts arose primarily from educational systems built for a single context of digital tool use engaging with students who wish to apply them in radically different contexts. The context mismatch between education model and student is particularly troublesome given that contextual knowledge, as opposed to detailed operational or strategic knowledge, was found to have the greatest impact on rapidly building design confidence in novices. Built on these findings, a new educational model, emphasizing end use context and ongoing, as needed education, is proposed as a guide to further curriculum development for the non-traditional student and classroom.

The mechanics of microelectromechanical systems (MEMS) are typically designed using a set of popular building blocks (rectangular cantilevers, folded flexure beams, crab legs etc.). Optimization of these structures or their variants is often performed using scaling laws, parametric optimization, or some insight gained from studying relationships between certain features and a device's behavior. Topology optimization is a more powerful tool that systematically generates the full topology of a design, including the size, shape, and location of features, and can satisfy several goals despite potentially complex relationships. The focus of this thesis is to answer the following question: Is it advantageous to design MEMS structures such as RF MEMS capacitive switches using topology optimization? This thesis takes the reader through a full design process. The problem setup and problem formulation are justified in depth. The mechanical behaviors of devices with stresses and stress gradients resulting from typical micro-fabrication processes are explained. The finite element simulations are described, and the modeling decisions that can be particularly relevant to other MEMS problems are highlighted. The topology optimization method is thoroughly explained, and the challenges and necessary adaptations to the method are exposed. Sets of topology optimized designs are presented; guidelines for future intuitive design are extracted from an examination of the resulting geometries. Experimental data is provided, justifying many of the decisions taken during the design process, and validating the finite element models and topology optimization results. The experimental results also provide supplemental understanding regarding capacitive switch mechanics. The new knowledge should be integrated into any future problem formulation. We conclude that topology optimization can be used for MEMS design, significantly increasing the design possibilities and solving complex, non-intuitive problems.

Research into how the gecko lizard is able to climb a wide variety of surfaces has re- vealed an adhesive system that takes a fundamentally different approach than is found in conventional pressure-sensitive adhesives such as sticky tape. The gecko's adhesive system is composed of setal stalks, each thinner than a human hair and terminating in spatulae only 250 nm across. The entire hierarchical system is composed of beta- keratin, a tough, hydrophobic material, somewhat harder than the alpha-keratin of human fingernails. The geometry of the setae and spatulae allow them to conform to surfaces in a manner similar to very soft materials, but without the tendency of tacky materials to become fouled with dirt. Using the gecko adhesive system as inspiration, Biomimetics and Dexterous Ma- nipulation Laboratory developed an adhesive that is suitable for robotic climbing ap- plications. The smallest features of this adhesive are arrays of sharp wedges molded from silicone rubber. A tapered feature was pursued because it is capable of repro- ducing the "frictional adhesion" property of the gecko's adhesive system. Frictional- adhesion defines a behavior for which increasing the shear stress imposed at a contact increases the available adhesive stress perpendicular to the surface. A consequence of frictional adhesion is that one can control the amount of adhesion by controlling the applied shear load. In the present case, the behavior arises from the fact that sharp wedge-shaped features initially present very little area as they are brought into contact with a surface. However, they bend over when the array is loaded in shear, so that the contact area and the adhesion grow in proportion. This thesis seeks to understand how the details of the tapered wedge geometry, including the wedge profile and angle of inclination, influence the frictional adhesive behavior. The analysis includes a combination of numerical finite element modeling and empirical pull-off tests. The constraints on material stiffness, wedge geometry and spacing are also studied, as affected by possible failure modes such as self-sticking of adjacent wedges (leading to "clumping"). The desire to test wedges at various angles of inclination lead to the development of a new micro-machining process for creating molds for the wedge arrays. This process affords much greater freedom to control the wedge size and geometry than a previous lithographic process. However, a byproduct of the machining process is that the wedges have a non-negligible surface roughness on their contacting faces, which compromises their performance. Consequently, a new process was developed to improve the surface finish by "inking" the molded wedges, depositing a thin film of liquid silicone rubber onto their faces and providing a smoother surface. The resulting microwedges achieve more than double the maximum adhesion and several times the adhesion at low levels of shear than previous microwedges from molds created using the lithographic process. Although the microwedges stick well to smooth, flat surfaces such as glass, they cannot conform to surfaces with undulations higher than a couple of micrometers. In addition, the array of microwedges must be precisely aligned with surfaces so that all wedges are uniformly loaded. To mitigate these limitations, some approximation to the gecko's compliant hierarchy of lamellae, setae and spatulae is needed. The solution presented in this thesis is a two-layer hierarchical system in which the arrays of wedges are supported by a larger array of angled pillars. In between the pillars and wedges is a film of solid silicone rubber, which bridges the gaps between pillars and helps to create a relatively uniform loading of the wedges. A combination of numerical analysis and empirical pull-off tests is used to understand the relationships among pillar dimensions, pillar spacing and film thickness that govern the performance of this structure. At one extreme, the loading can become sufficiently non-uniform that some wedges lose contact with the surface, resulting in a loss of adhesion. At the other extreme, the structure is too stiff to accommodate surface undulations and misalignment. The thesis concludes with a summary of the results on wedges and hierarchical adhesive structures, and discusses the implications for future work.

Design transforms people and the stuff they make. How technical engineers learn and advance a human-centered design approach, and what catalysts and barriers for their learning exist, will be illustrated with research done with student mechanical engineering designers engaged in work practice. Ambidextrous Mindsets for Innovation is a framework for relating designerly ways of knowing-doing-acting and engineering ways of knowing-doing-acting. Empirical findings are based on evidence collected from nine engineering design teams in a graduate mechanical engineering course. The focus is on their prototyping habits over time, supported by observations of team meetings and review of team documentation reports.

Concept generation activity, an activity in which a number of design concepts are generated for further evaluation through prototyping and testing, is an important stage in the engineering design process. In design practice and design education, concept generation activity is often conducted in teams. During this activity, designers interact with one another to generate a number of design concepts. Prior research on concept generation activity in design teams has either looked into understanding the inter-relations between concepts generated, or into identifying specific behaviors in interpersonal interaction. There is a lack of understanding of the manner through which design concepts are generated moment-to-moment from the interpersonal interactions between designers. The present work aims to provide an explanation of concept generation through moment-to-moment interpersonal interaction behaviors by developing a visual representation of the phenomenon. In order to develop this visual representation, an empirical study is conducted in which the concept generation activity of two teams is analyzed through the point of view of collective improvisation. Based on improvisation principles, a visual notation called the Interaction Dynamics Notation is developed. In order to evaluate the effectiveness of this visual notation, it is applied to concept generation activity of three teams selected from a field context of ongoing graduate engineering design projects. The resultant visual representation of the concept generation activity is successful in identifying eight patterns of interaction that characterize moment-to-moment concept generation, such as transitions between ideas and facts, the presence of periods of sustained idea expressions, the occurrence of improvisation behavior, question-asking and humor in periods of sustained idea expressions, the existence of blocking behavior which at times influenced further ideas, the presence of interruptions that were not detrimental to concept generation, and the resumption of concepts in conversation. The Interaction Dynamics Notation thus enables us to 'see' concept generation through moment-to-moment interpersonal interactions in design teams. The main contribution of this study is the development of a visual representation, the Interaction Dynamics Notation that brings together prior research on concept generation and prior research on interpersonal behaviors in a team. The notation provides a detailed explanation of concept generation activity through moment-to-moment interpersonal interactions in an intuitive visual form.

This dissertation explores ways to embed human needs and equity into sustainable energy and transportation systems models. Part I explores ways to integrate human perspective in wind and solar models. Part II takes a holistic approach to integrating human perspective in sociotechnical models with an explicit focus on integrating equity. For the second part, we focus on the transition to clean mobility for all - how to transition to a decarbonized transportation sector in a way that is inclusive and empowers communities, especially those that are underrepresented and underserved, to have choice over their transportation. Sustainable energy and transportation systems are crucial to decarbonizing the global energy portfolio and fighting climate change. A deeper examination reveals that not everyone's needs are served equitably in the current energy and transportation systems nor in the transition to sustainable ones. There is a need to ensure these systems are studied, analyzed, and implemented from a human-centered design approach to ensure efficient engineered outcomes are equitably designed to meet the needs of the people who rely on them and the planet in which they exist. Part I contains two separate studies. The first study presents an agent-based model that investigates decision making and interactions of landowners and developers during the wind farm development process. The main contribution of this study is a scenario analysis to inform how landowner decisions and developer actions can affect wind project implementation. The second study in Part I presents a decision model that can be used to help funding agencies allocate solar research and development funding based on industry priorities. The decision model in this study is based on a utility-scale solar cost model, built through the lens of a developer, and a sensitivity analysis using industry data. The main contribution of this study is an industry-driven approach to prioritizing human-driven research and development projects when allocating funding and a cost model that includes both hard and soft costs. Part II focuses on the transition to clean mobility for all. The first half of Part II formulates the overall problem, reviews past literature to understand ways that equity has been integrated into energy and transportation models, and presents a human-centered framework to approach optimizing sociotechnical systems. The main contributions of the first half of Part II are 1) a definition of True Decommissioning, the removal of internal combustion engine vehicles permanently, quickly, and equitably and 2) our Human-Centered Design Cycle framework to build optimization models from multiple points of view while keeping equity front and center. The second half of Part II applies the Design Cycle to a clean mobility case study in Sonoma County, California. These chapters present work to define the problem perspective in the county, conduct community engagement, and suggest redesign directions for an equity mobility program to better serve the county's low-income communities. The main contributions of the second half of Part II are 1) a strategy to engage with communities, integrating data-driven and informal interview approaches, and 2) learnings from our case study that can be used to guide future mobility work in Sonoma County as well as other communities working toward the broader goal of transitioning to clean mobility for all. Human perspective can show up in multiple forms within models and can change outcomes that drive decision making, depending on what perspectives are included. Gathering both qualitative and quantitative data are equally important when designing models. Integrating equity into modeling is complex and requires careful efforts to define the problem context and stakeholders before any mathematical formulas are considered. The case study in Sonoma County showed that equity must be driven from granular analyses - high-level approaches risk averaging out certain populations in the analyses and may not contribute to driving equitable outcomes. Future work to apply the Design Cycle in other areas and sociotechnical systems may offer additional insights to help speed the transition to sustainable energy and transportation without causing undue harm to communities

Engineering design researchers tend to study design processes and methodology from one of two primary approaches. The first, and more traditional approach, is the positivist treatment of design as rational problem solving, exemplified by Herbert Simon. A second, somewhat less prevalent approach is illustrated in Donald Schön's constructivist theory of design as reflective practice. Schön's study of reflective practice in design centers on the concept of "reflection-in-action", referring to intentional and conscious reflection by the designer. This perspective serves as the starting point and foundation for this dissertation research. Our focus remains primarily on the individual designer, whose mind serves as the locus of reflection, but with attention to the physical, social, and mental context, which form the setting for reflective practice. The current work was driven by the following questions: 1. What kinds of activities do designers engage in when they get ideas? 2. Can we identify common characteristics of these activities and their context? 3. Do some activities and/or characteristics of activities correlate better than others with the generation of creative ideas? 4. Are reflective practices outside of the work tasks of design a frequent source of creative ideation and insight for designers? The initial phase was largely exploratory in nature and grounded in observation, examining design artifacts for evidence of reflective practice, and surveying designers on the context surrounding their recent ideas. Analysis reveals that idealogs, as artifacts of design work, show evidence of many different reflective practices engaged by student designers in an ME design course. It also leads us to an expanded view and refined understanding of what might be considered a reflective practice and a catalyst for ideation. In the second phase, designers talked through and sketched out the design process they used for a recent project, yielding rich descriptions of novice and intermediate designers' design processes and reflective practices. Some common trends in descriptions of the characteristics of participants' reflective practices include: reference to "mindless" activities, exercise and physical activities, conversation/social activities, and prototyping. Phase three consistsed of two surveys aimed at identifying characteristics of reflective practices. The first was geared toward discovering what general activities designers engage in when they get ideas and differentiating between most and least helpful activities through a series of bipolar attributes. The second asked participants to focus on a particular idea or insight they had, and then to describe the contextual setting in which they had gotten it. We find that designers use a variety of reflective practices. Some activities, such as conversations with friends and family and thinking before going to bed, are not traditionally thought of as productive work activities, and yet respondents often reported them as helpful to creative ideation. A second survey asked respondents about their reflective practices in light of an actual experience of an "Aha!" moment. An exploratory factor analysis conducted on the Likert section of this survey reveals four factors, including engagement, attention, stress, and enthusiasm.

Many complex, biologically-derived materials have extremely useful properties (think wood or silk), but suf- fer from production, manufacturing, and processing limitations. Cells naturally specialize in making complex biomaterials on a micro scale. This work explores a technology concept combining this ability with the re- cently emergent fields of synthetic biology and additive manufacturing in which the end product is a nonliving biomaterial with human-designed shape, structure and composition. A 3D printer capable of printing living cells with near single-cell resolution is used to create 3D-structured arrays of cells bioengineered to secrete different materials. The cells produce the materials in rates and quantities determined by human-controlled stimuli. A proof of concept is described consisting of a two-material array of non-structural proteins. Each step in the end-to-end demonstration has been proven to reach the minimum level of critical functionality. Adding a vast new set of biomaterials, both natural and newly designed, to the traditional metal, plastic and ceramic material toolkit has applications limited by our future imagination; this work is an important first step on that path.