<p>In this thesis, a study of the rational design and fabrication of microfluidic systems for microsphere generation is presented. The required function of microfluidic systems is to produce microspheres with the following attributes: (i) the microsphere size being around one micron or less, (ii) the size uniformity (in particular coefficient of variation (CV)) being less than 5%, and (iii) the size range being adjustable as widely as possible.</p> <p>Micro-electro-mechanical system (MEMS) technology, largely referring to various micro-fabrication techniques in the context of this thesis, has been applied for decades to develop microfluidic systems that can fulfill the foregoing required function of microsphere generation; however, this goal has yet to be achieved. To change this situation was a motivation of the study presented in this thesis.</p> <p>The philosophy behind this study stands on combining an effective design theory and methodology called Axiomatic Design Theory (ADT) with advanced micro-fabrication techniques for the microfluidic systems development. Both theoretical developments and experimental validations were carried out in this study. Consequently, the study has led to the following conclusions: (i) Existing micro-fluidic systems are coupled designs according to ADT, which is responsible for a limited achievement of the required function; (ii) Existing micro-fabrication techniques, especially for pattern transfer, have difficulty in producing a typical feature of micro-fluidic systems - that is, a large overall size (~ mm) of the device but a small channel size (~nm); and (iii) Contemporary micro-fabrication techniques to the silicon-based microfluidic system may have reached a size limit for microspheres, i.e., ~1 micron.</p> <p>Through this study, the following contributions to the field of the microfluidic system technology have been made: (i) Producing three rational designs of microfluidic systems, device 1 (perforated silicon membrane), device 2 (integration of hydrodynamic flow focusing and crossflow principles), and device 3 (liquid chopper using a piezoelectric actuator), with each having a distinct advantage over the others and together having achieved the requirements, size uniformity (CV ⤠5%) and size controllability (1-186 &#x00B5;m); (ii) Proposing a new pattern transfer technique which combines a photolithography process with a direct writing lithography process (e.g., focused ion beam process); (iii) Proposing a decoupled design principle for micro-fluidic systems, which is effective in improving microfluidic systems for microsphere generation and is likely applicable to microfluidic systems for other applications; and (iv) Developing the mathematical models for the foregoing three devices, which can be used to further optimize the design and the microsphere generation process.</p>

<p>In this thesis, a study of the rational design and fabrication of microfluidic systems for microsphere generation is presented. The required function of microfluidic systems is to produce microspheres with the following attributes: (i) the microsphere size being around one micron or less, (ii) the size uniformity (in particular coefficient of variation (CV)) being less than 5%, and (iii) the size range being adjustable as widely as possible.</p> <p>Micro-electro-mechanical system (MEMS) technology, largely referring to various micro-fabrication techniques in the context of this thesis, has been applied for decades to develop microfluidic systems that can fulfill the foregoing required function of microsphere generation; however, this goal has yet to be achieved. To change this situation was a motivation of the study presented in this thesis.</p> <p>The philosophy behind this study stands on combining an effective design theory and methodology called Axiomatic Design Theory (ADT) with advanced micro-fabrication techniques for the microfluidic systems development. Both theoretical developments and experimental validations were carried out in this study. Consequently, the study has led to the following conclusions: (i) Existing micro-fluidic systems are coupled designs according to ADT, which is responsible for a limited achievement of the required function; (ii) Existing micro-fabrication techniques, especially for pattern transfer, have difficulty in producing a typical feature of micro-fluidic systems - that is, a large overall size (~ mm) of the device but a small channel size (~nm); and (iii) Contemporary micro-fabrication techniques to the silicon-based microfluidic system may have reached a size limit for microspheres, i.e., ~1 micron.</p> <p>Through this study, the following contributions to the field of the microfluidic system technology have been made: (i) Producing three rational designs of microfluidic systems, device 1 (perforated silicon membrane), device 2 (integration of hydrodynamic flow focusing and crossflow principles), and device 3 (liquid chopper using a piezoelectric actuator), with each having a distinct advantage over the others and together having achieved the requirements, size uniformity (CV ⤠5%) and size controllability (1-186 &#x00B5;m); (ii) Proposing a new pattern transfer technique which combines a photolithography process with a direct writing lithography process (e.g., focused ion beam process); (iii) Proposing a decoupled design principle for micro-fluidic systems, which is effective in improving microfluidic systems for microsphere generation and is likely applicable to microfluidic systems for other applications; and (iv) Developing the mathematical models for the foregoing three devices, which can be used to further optimize the design and the microsphere generation process.</p>

QA bearing technologies Ltd. (hereafter QA) is a custom manufacturer of bearings in a variety of types and sizes. This research concerns one of the processes in QA’s bearing manufacturing in which the individual bearings, once assembled, are packaged to prevent corrosion and attack from any environmental influence. QA currently employs a manual process, which is time-consuming and significantly limits QA’s productivity. This greatly raises a need to improve this process through the design of an automated process for bearing packaging. Various kinds of packaging machine are available in the market for this application. However, most of them are designed for general packaging purpose and simply combining them may result in the functional overlap as applied to the packaging process. This research aims to design an automatic bearing packaging system (ABPS) based on an advanced design theory, i.e., Axiomatic Design Theory (ADT). In the first part of this research, a set of general functional requirements (FRs) and constraints (CONs) were defined specifically based on the needs from the customers. All FRs were maintained independent to each other such that the following design wouldn’t result in functional overlap. Then, design parameters (DPs) in general level were created to satisfy the defined FRs, each being a functionally independent subsystem consists of both custom-design components and products existing in the market. The second part of the research was to decompose the FRs and DPs based on independent axiom of ADT into further levels until the conceptual design was accomplished. In this process, acceptable alternatives in different hierarchies were proposed for comparison in the decision making process. Also, the relationship between FRs and DPs in the same level was always maintained one-to-one, which allows readily for modification in future, if needed. In the third part of this research, the information axiom of ADT was utilized to find the best solution from alternatives. For this, each alternative was evaluated in terms of the information content that reflects the possibility of satisfying the objective FR. The one with least information content was determined as the best alternative. As a result of this research, two solutions with different degree of automation were recommended for the bearing packaging system. The first solution is featured with higher degree of automation and capable of packaging bearings with limited human interface and as result, the total cost for its implementation is relatively high. The second solution integrates semi-automated machines and simplified sealing strategy and as such, the cost for its implementation is significantly reduced. After the conceptual design is complete, ADT is further applied in the detailed design level for oiling system with custom-designed components and mechanism. For the design of certain DPs, the design process applying ADT is used to compare with conventional methods, proved to be more efficient and simplified. Eventually, the final solution proposed for the detailed design of oiling system is consistent with independent axiom of ADT.

In this research, component oriented development is supported with design guidance by extending the Axiomatic Design Theory for component orientation, and utilizing domain engineering and ontology mechanisms. Guidance is offered in the form of suggesting missing components and discovering incompatibilities among the candidate elements of software development, corresponding to different phases such as requirement analysis, design, and implementation. A mature domain concept is developed suggesting the availability of reference models for customer needs, software system requirements, software design, and also a rich set of implemented components. As the system is being defined starting with the customer needs and progressing towards components, at every step the developer is presented what is available in the domain and what becomes unavailable. This guidance is based on the selections made so far, utilizing ontology based constraint checking. Feature Models are incorporated for modeling customer needs. Case studies are presented for demonstration purposes.

Design theories and methodologies are guidelines to develop design solutions. Among many, the Axiomatic design theory (ADT) and Systematic design procedures (SDP) are two well-known approaches to design. For practical applications, the choice of the design methodology is difficult as there is no study to compare them. To close in such gap in literature, this thesis presents a study on comparison of these two design approaches. To facilitate the comparison, design of a solid state fermenter was taken as a vehicle. The fermenter chosen for this study is was used for detoxification of phorbol esters from Jatropha curcas. Jatopha curcas is a woody plant and is one of the major sources for the production of bio-diesel as it is readily available and has unique composition. Processing Jatopha curcas for biodiesel also yields protein rich Jatopha curcas seed cake. This can be used as animal feedstock, cattle fodder or live feed stock. It is however known that phorbol esters present in the seed cake hinder the utilization of the seed cake as live feed stock. Solid state fermentation by fungi is an effective process to denature phorbol esters, which has been demonstrated at the laboratory scale. Development of an industrial scale solid state fermenter (SSF) is necessary. This study applies SDP and ADT the same deign problem of SSF and compared based on the result of the design. It is noted that in ADT, the evaluation of design alternatives neither considers the cost of the system under design nor the delivery time of the system, but SDP does. To make the comparison on the same ground, an extension of ADT enabling it to consider the cost and delivery time (or time) was developed. Several conclusions can be drawn from this study and they are: (1) ADT and SDP are complementary to each other and the one that integrates both is more effective to design; (2) The essence of Axiom 2 of ADT is to evaluate design alternatives with all factors that lead to difficulty to realize the design, but unfortunately the information content in the current ADT literature only considers the functional or quality aspect; (3) Previous reports suggest the presence of zigzag process only in ADT, However in this study it is evident that SDP exercises the zigzag process as well; (4) the proposed formulation of information content by taking into consideration of the quality, cost, time aspects is more effective in design practice as quite often the cost and time are very important aspects to the customer. The contribution of this thesis study is of two-fold. First, the SSF designed in this study is a pilot one in the field of the biochemical process and it has potential to be implemented. Second, this study concludes several unique findings of ADT and SDP with their relationship, which have further resulted in an integrated ADT and SDP design approach and a more complete formulation of information content capable of evaluating design alternatives from all aspects rather than the functional aspect only.

The aesthetic aspect of a functional product is growing to be an important reason for the consumers choice to buy the product. Despite this importance, aesthetics has not generally been incorporated into engineering design which makes much sense of functional and ergonomic designs. The study presented in this thesis aims to remedy this observed gap. The study focuses on the integration of aesthetic attributes with functional attributes of a product and on the quantification of the aesthetic principle from fine arts into design variables of the product. In particular, two hypotheses underlie this study: (1) design variables can be classified in terms of their relevance to functional, ergonomic, and aesthetic attributes, and (2) a particular aesthetic principle, namely visual balance, helps to achieve an improved aesthetic product.<p>The cell phone is used to ground this study. A statistic experiment using the cell phone product positively tests the first hypothesis, resulting in two design variable which are only related to the aesthetic attribute of the cell phone product. The study of the visual balance principle results in a more general formula which relates design variables to visual balance with consideration of both geometry and color of the cell phone product. Finally, another statistic experiment is designed, which positively tests the second hypothesis.<p>This study concludes: (1) the effective integration of aesthetics with function and ergonomics requires an analysis and classification of design variables, and (2) there is a potential to quantify all aesthetic principles from fine arts into design variables.

The aesthetic aspect of a functional product is growing to be an important reason for the consumers choice to buy the product. Despite this importance, aesthetics has not generally been incorporated into engineering design which makes much sense of functional and ergonomic designs. The study presented in this thesis aims to remedy this observed gap. The study focuses on the integration of aesthetic attributes with functional attributes of a product and on the quantification of the aesthetic principle from fine arts into design variables of the product. In particular, two hypotheses underlie this study: (1) design variables can be classified in terms of their relevance to functional, ergonomic, and aesthetic attributes, and (2) a particular aesthetic principle, namely visual balance, helps to achieve an improved aesthetic product.<p>The cell phone is used to ground this study. A statistic experiment using the cell phone product positively tests the first hypothesis, resulting in two design variable which are only related to the aesthetic attribute of the cell phone product. The study of the visual balance principle results in a more general formula which relates design variables to visual balance with consideration of both geometry and color of the cell phone product. Finally, another statistic experiment is designed, which positively tests the second hypothesis.<p>This study concludes: (1) the effective integration of aesthetics with function and ergonomics requires an analysis and classification of design variables, and (2) there is a potential to quantify all aesthetic principles from fine arts into design variables.