This thesis investigates end-effector systems used in a chemomechanical scribing process. Chemomechanical scribing is a method of patterning silicon to selectively deposit a monolayer of material on the surface of the silicon. This thesis details the development of a unique end-effector for chemomechanical scribing using a compliant mechanism solution. The end-effector is developed to scribe lines that have uniform geometry and produce less chipping on the surface of the silicon. The resulting scribing mechanism is passively controlled, has high lateral stiffness, and low axial stiffness. The mechanism is analyzed using the pseudo-rigid-body model and linear-elastic beam method to determine the axial stiffness, finite element methods to determine the lateral stiffness, and fatigue analysis to determine mechanism cycle life. This thesis also investigates the significance of mechanical factors on the chemomechanical scribing process using the compliant end-effector. The factors examined are scribing force, scribing speed, tip geometry, wafer orientation, and wetting liquid. The factors are analyzed using a two-step approach: first, an analysis of the influence of the mechanical factors on line characteristics and second, an analysis of the influence of line characteristics on line performance.

MEMS (MicroElectroMechanical Systems) sensors are used in acceleration, flow, pressure and force sensing applications on the micro and macro levels. Much research has focused on improving sensor precision, range, reliability, and ease of manufacture and operation. One exciting possibility for improving the capability of micro sensors lies in exploiting the piezoresistive properties of silicon, the material of choice in many MEMS fabrication processes. Piezoresistivity—the change of electrical resistance due to an applied strain—is a valuable material property of silicon due to its potential for high signal output and on-chip and feedback-control possibilities. However, successful design of piezoresistive micro sensors requires a more accurate model of the piezoresistive behavior of polycrystalline silicon. This study sought to improve the existing piezoresistive model by investigating the piezoresistive behavior of compliant polysilicon structures subjected to tensile, bending and combined loads. Experimental characterization data showed that piezoresistive sensitivity is greatest and mostly linear for silicon members subject to tensile stresses and nonlinear for beams in bending and combined stress states. The data also illustrated the failure of existing piezoresistance models to accurately account for bending and combined loads. Two MEMS force and displacement sensors, the integral piezoresistive micro-Force And Displacement Sensor (FADS) and Closed-LOop sensor (CLOO-FADS), were designed and fabricated. Although limited in its piezoresistive sensitivity and out-of-plane stability, the FADS design showed promise of future application in microactuator characterization. Similarly, the CLOO-FADS exhibited possible feedback control capability, but was limited by control circuit complexity and implementation challenges. The piezoresistive behavior exhibited by the Thermomechanical In-plane Microactuator (TIM) led to a focused effort to characterize the TIM's behavior in terms of force, displacement, actuation current and mechanism resistance. The gathered data facilitated the creation of an empirical, temperature-dependent model for the specific TIM. Based on the assumption of a nearly constant temperature for each current level, the model predicted the force and displacement for a given fractional change in resistance. Despite the success of the empirical model for the test TIM device, further investigation revealed the necessity of a calibration method to enable the model's application to other TIM devices.

The development of current golf club designs has followed an evolutionary process starting with the original wooden heads of a hundred years ago, to the thin-walled, hollow body titanium heads of today. Current designs utilize what has become known as the trampoline effect to increase the efficiency of the ball-club impact, which has a number of limiting factors that restrict clubhead performance. These limitations provided the motivation for this research to explore new mechanisms by which the efficiency of the ball club impact could be increased. In particular this research focuses on the development of compliant mechanisms to increase club performance. The results of this research, from concept development to initial prototype plans, are included in this study. A discussion of past and current research in the area of golf club design is presented. A new list of performance metrics for golf clubs and a number of new golf club concepts is also presented. This is followed by a static and dynamic analysis of the most promising golf club configuration. The study is concluded with a concept validation analysis and a presentation of possible prototype configurations for a new golf club design.

Feedback control of MEMS devices has the potential to significantly improve device performance and reliability. One of the main obstacles to its broader use is the small number of on-chip sensing options available to MEMS designers. A method of using integrated piezoresistive sensing is proposed and demonstrated as another option. Integrated piezoresistive sensing utilizes the inherent piezoresistive property of polycrystalline silicon from which many MEMS devices are fabricated. As compliant MEMS structures flex to perform their functions, their resistance changes. That resistance change can be used to transduce the structures' deflection into an electrical signal. This dissertation addresses three topics associated with integrated piezoresistive sensing: developing an empirical model describing the piezoresistive response of polycrystalline-silicon flexures, designing compliant MEMS with integrated piezoresistive sensing using the model, and implementing feedback control using integrated piezoresistive sensing. Integrated piezoresistive sensing is an effective way to produce small, reliable, accurate, and economical on-chip sensors to monitor compliant MEMS devices. A piezoresistive flexure model is presented that accurately models the piezoresistive response of long, thin flexures even under complex loading conditions. The model facilitates the design of compliant piezoresistive MEMS devices, which output an electrical signal that directly relates to the device's motion. The piezoresistive flexure model is used to design a self-sensing long displacement MEMS device. Motion is achieved through contact-aided compliant rolling elements that connect the output shaft to kinematic ground. Self-sensing is achieved though integrated piezoresistive sensing. An example device is tested that demonstrates 700 micrometers of displacement with a sensing resolution of 2 micrometers. The piezoresistive microdisplacement transducer (PMT) is a structure that uses integrated piezoresistive sensing to monitor the output displacement of a thermomechanical inplane microacutator (TIM). Using the PMT as a feedback sensor for closed-loop control of the TIM reduced the system's response time from 500~$mu$s to 190~$mu$s, while maintaining a positioning accuracy of $pm$29~nm. Feedback control of the TIM also increased its robustness and reliability by allowing the system to maintain its performance after it had been significantly damaged.

Proper positioning of Microelectromechanical Systems (MEMS) components influences the functionality of the device, especially in devices where the motion is in the range of hundreds of micrometers. There are two main obstacles to positioning: off-axis displacement, and position determination. This work studies four large-displacement devices, their axial and transverse stiffness, and piezoresistive response. Methods for improving the device characteristics are described. The folded-beam suspension, small X-Bob, large X-Bob and double X-Bob were characterized using non-dimensional metrics that measure the displacement with regard to the size of the device, and transverse stiffness with regard to axial stiffness. The stiffness in each direction was determined using microprobes to induce displacement, and microfabricated force gauges to determine the applied force. The large X-Bob was optimized, increasing the transverse stiffness metric by 67%. Four-point resistance testing and microprobes were used to determine the piezoresistive response of the devices. The piezoresistive response of the X-Bob was maximized using an optimization routine. The resulting piezoresistive response was over seven times larger than that of the initial design. Piezoresistive encoders for ratcheting actuation of large-displacement MEMS are introduced. Four encoders were studied and were found to provide information on the performance of the ratcheting actuation system at frequencies up to 920 Hz. The PMT encoder produced unique signals corresponding to distinct ideal and non-ideal operation of the ratchet wheel actuation system. Encoders may be useful for future applications which require position determination.

The purpose of this research is to investigate the use of compliant mechanisms in space applications and design, analyze, and test a compliant space mechanism. Current space mechanisms are already highly refined and it is unclear if significant improvements in performance can be made by continuing to refine current designs. Compliant mechanisms offer a promising opportunity to change the fundamental approach to achieving controlled motion in space systems and have potential for dramatic increases in mechanism performance given the constraints of the space environment. A compliant deployment hinge was selected for development after industry input was gathered. Concepts for large-displacement compliant hinges are investigated. A design process was developed that links the performance requirements of deployment to the design parameters of a deployment hinge. A large-displacement monolithic compliant rotational hinge, the Flex-16, is designed, analyzed, and tested. It was developed for possible application as a spacecraft deployment hinge and designs were developed using three different materials (polypropylene, titanium, and carbon nanotubes) and manufacturing processes (CNC milling, electron beam manufacturing metal rapid prototyping, and a carbon nanotube framework) on two size scales (macro and micro). A parametric finite element model allowed for prediction of prototype behavior before fabrication. The Flex-16 hinge is capable of 90 degrees of deflection without failure or contact and can be designed to meet industry requirements for space.

Origami can be a powerful source of design inspiration in the creation of reconfigurable systems with unparalleled performance. This thesis provides fundamental tools for designers to employ as origami-based designs are pursued in their respective fields of expertise. The first chapter introduces origami and makes connections between origami and engineering design through a survey of engineered applications and characterizing the relationship between origami and compliant mechanisms. The second chapter evaluates the creasing of non-paper sheet materials, such as plastics and metals, to facilitate origami-based compliant mechanism design. Although it is anticipated that most origami-based design will result from surrogate folds (indirect methods of replacing the crease), it is valuable to provide information that may help in more direct approaches for origami-based design in materials other than paper. Planar sheets of homogeneous material are considered as they maintain the principles fundamental to origami (flat initial state, low cost, readily available). The reduced stiffness along the axis of the crease is an enabling characteristic of origami. Hence a metric based on the deformation of the crease compared to the deformation of the panels enables engineering materials to be evaluated based on their ability to achieve the "hinge-like" behavior observed in folded paper. Advantages of both high and low values of this metric are given. Testing results (hinge indexes, residual angles, localized hinge behavior and cyclic creasing to failure) are presented for various metals and polymers. This methodology and subsequent findings are provided to enable origami-based design of compliant mechanisms. The third chapter proposes a basic terminology for origami-based design and presents areas of considerations for cases where the final engineering design is directly related to a crease pattern. This framework for navigating from paper art to engineered products begins once the crease pattern has been selected for a given application. The four areas of consideration are discussed: 1) rigid foldability 2) crease characterization 3) material properties and dimensions and 4) manufacturing. Two examples are concurrently presented to illustrate these considerations: a backpack shell and a shroud for an adjustable C-Arm x-ray device used in hospitals. The final chapter provides concluding remarks on origami-based design.

This thesis addresses a number of challenges designers face when designing deployable origami-based arrays, specifically joint selection, design, and placement within an array. In deployable systems, the selection and arrangement of joint types is key to how the system functions. The kinematics and performance of an array is directly affected by joint performance. This work develops joint metrics which are then used to compare joint performances, constructing a tool designers can use when selecting joints for an origami array. While often a single type of joint is used throughout an array, this work shows how using multiple types of joints within the same array can offer benefits for motion deployment, and array stiffening. Origami arrays are often used for their unique solutions for stowing and deploying large planar shapes. Folds, enabled through joints, within these patterns allow the arrays to fold compactly. However, it can be difficult to fully deploy arrays, particularly array designs with a high number of joints. In addition, it is a challenge to stabilize a fully deployed array from undesired re-folding. This work introduces a strain-energy storing joint that is used to deploy and stiffen foldable origami arrays, the Lenticular Lock (LentLock). Geometry of the LentLock is introduced and the deploying and stiffening performance of the joint is shown. Folds within an origami array create the constraints that link motion between panels, and can be used to create kinematic benefits, such as creating mechanisms with a single degree-of-freedom. While many fold-constraints are required to define motion, this work shows that origami-based system contain many redundant constraints. The removal of redundant joints does not affect the motion of the array nor the observed mobility, but may decrease the likelihood of binding, simplify the overall system and decrease actuation force. This work introduces a visual and iterative approach designers can use to identify redundant constraints in origami patterns, and techniques that can be used to remove the identified redundant constraints. The presented techniques are demonstrated by removing redundant constraints from prototyped origami mechanisms. As a result of this work, designers will be better able to approach and design deployable origami-based mechanisms.

A pragmatic method for designing compliant mechanisms is developed in this thesis, by selecting among existing mechanisms one that may be modified as required. This method complements existing techniques by answering questions of the existence and multiplicity of solutions for the given specifications of a practical problem. The premise for the method is a 2D map that juxta- poses the problem-specifications and the characteristics of compliant mechanisms in a database. The selection of the most suitable mechanisms is similar to Ashby's method of material selection. In our method, stuffiness, inertia, and the inherent kinematic characteristics of compliant mechanisms are analogous to material properties in Ashby's method. These characteristics capture the lumped behavior of compliant mechanisms in static and dynamic situations using spring-lever (SL) and spring-mass-lever (SML) models. The work includes the development of computation- ally efficient methods to compute the SL and SML model characteristics of single-input and single-output compliant mechanisms. Also developed in this work is a method to determine a feasible map by solving the governing equations of equilibrium and several inequalities pertaining to problem- specifications. The map helps not only in assessing the feasibility of the specifications but also in re-designing the mechanisms in predetermined ways to nd multiple solutions, all of which account for practical considerations. The method pays due attention to the overall size, strength considerations, manufacturability, and choice of material. It also enables minimal alterations of the problem-specifications when the user prefers a particular mechanism in the database. All these features are implemented in a web-based Java program with a graphical user interface that can be accessed at http://www.mecheng.iisc.ernet.in/ m2d2/CM design. Six case- studies that include micro machined inertial sensors, miniature valve mechanisms, ultra-sensitive force sensors, etc., are documented in detail to demonstrate the usefulness of the method in practice.

The aim of this study is to design a compliant lock mechanism for a dishwasher, using a systematic approach. Functionally binary pinned-pinned segment that exhibits bistable behavior is utilized. Pseudo-rigid-body model of the whole mechanism and the half segment is developed separately and the corresponding calculations are carried out. Among current solutions a different method namely &ldquo / arc fitting method&rdquo / is developed and it is utilized to construct the model. A software code is written to get the exact solutions, which require the evaluation of elliptic integrals. Results are compared with the analytical model and confirmed with physical prototype. Predefined tip forces are seen to provide the transition from one stable position to other. Durability, reliability and compactness characteristics are particularly considered.