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The creation of new systems for nanomanufacturing can be catalysed by a knowledge of manufacturing systems. A method for comparing macro-scale manufacturing metrics and nanoscale manufacturing processes allows a design engineer to objectively evaluate similarities between macro-scale and nano-scale processes. The result of mapping manufacturing metrics is that a design engineer will have a better understanding of which currently-available manufacturing technology can be easily modified to enable a given nano-scale process. Furthermore, a design engineer will be able to clearly identify areas where new technology must be developed in order to satisfy the performance requirements for a nanomanufacturing process not met by existing technology. A metric mapping method for comparing manufacturing process metrics to nanomanufacturing processes has been developed, which can be used to aid in the design of systems for manufacturing nano-scale products; metric mapping has been utilised to help create a machine for enabling high-throughput dip pen nanolithography.

Feature size predictions in dip pen nanolithography are typically based upon the constant transport rate or the constant tip−concentration approximations. Models based upon these approximations are inaccurate due to the erroneous assumption that the diffusion of ink upon the surface and ink dissolution at the tip are independent. Herein, we explain that these two steps are related and that they share the same ink flow via the meniscus. We use this insight to generate a comprehensive ink transport model. Our model provides new insight into the (i) relative importance of tip-side transport and surface diffusion, (ii) cause of intermittent line writing at high writing speeds, and (iii) critical role of proper tip inking with respect to feature size accuracy and high-speed writing. We show that the constant rate and constant tip−concentration approaches are limiting cases of the same model, thereby unifying the two approaches and reducing errors in line width prediction by up to 30%.

A process flow is described for the low cost, flexible fabrication of metal micro-electromechanical systems (MEMS) with high performance integrated sensing. The process is capable of producing new designs in ≈1 week at an average unit cost of <$1 k/device even at batch sizes of ≈1–10, with expected sensing performance limits of about 135 dB over a 10 kHz sensor bandwidth. This is a ≈20× reduction in cost, ≈25× reduction in time, and potentially >30× increase in sensing dynamic range over comparable state-of-the-art compliant nanopositioners. The nonlithographically based microfabrication (NLBM) process is uniquely suited to create high performance nanopositioning architectures which are customizable to the positioning requirements of a range of nanoscale applications. These can significantly reduce the cost of nanomanufacturing research and development, as well as accelerate the development of new processes and the testing of fabrication process chains without excess capital investment. A six degrees-of-freedom (6DOF) flexural nanopositioner with integrated sensing for all 6DOF was fabricated using the newly developed process chain. The fabrication process was measured to have ≈30 μm alignment. Sensor arm, flexure, and trace widths of 150 μm, 150 μm, and 800 μm, respectively, were demonstrated. Process capabilities suggest lower bounds of 25 μm, 50 μm, and 100 μm, respectively. Dynamic range sensing of 52 dB was demonstrated for the nanopositioner over a 10 kHz sensor bandwidth. Improvements are proposed to approach sensor performance of about 135 dB over a 10 kHz sensor bandwidth.

Herein, we discuss the folding of highly compliant origami structures—“Soft Origami.” There are benefits to be had in folding compliant sheets (which cannot self-guide their motion) rather than conventional rigid origami. Example applications include scaffolds for artificial tissue generation and foldable substrates for flexible electronic assemblies. Highly compliant origami has not been contemplated by existing theory, which treats origami structures largely as rigid or semirigid mechanisms with compliant hinges—“mechanism-reliant origami.” We present a quantitative metric—the origami compliance metric (OCM)—that aids in identifying proper modeling of a homogeneous origami structure based upon the compliance regime it falls into (soft, hybrid, or mechanism-reliant). We discuss the unique properties, applications, and design drivers for practical implementation of Soft Origami. We detail a theory of proper constraint by which an ideal soft structure's number of degrees-of-freedom may be approximated as 3n, where n is the number of vertices of the fold pattern. Buckling and sagging behaviors in very compliant structures can be counteracted with the application of tension; we present a method for calculating the tension force required to reduce sagging error below a user-prescribed value. Finally, we introduce a concept for a scalable process in which a few actuators and stretching membranes may be used to simultaneously fold many origami substructures that share common degrees-of-freedom.

Wrinkling of thin films is a strain-driven process that enables scalable and low-cost fabrication of periodic micro- and nano-scale patterns. In the past, single-period sinusoidal wrinkles have been applied for thin-film metrology and microfluidics applications. However, real-world adoption of this process beyond these specific applications is limited by the inability to predictively fabricate a variety of complex functional patterns. This is primarily due to the inability of current tools and techniques to provide the means for applying large, accurate, and nonequal biaxial strains. For example, the existing biaxial tensile stages are inappropriate because they are too large to fit within the vacuum chambers that are required for thin-film deposition/growth during wrinkling. Herein, we have designed a compact biaxial tensile stage that enables (i) applying large and accurate strains to elastomeric films and (ii) in situ visualization of wrinkle formation. This stage enables one to stretch a 37.5 mm long film by 33.5% with a strain resolution of 0.027% and maintains a registration accuracy of 7 μm over repeated registrations of the stage to a custom-assembled vision system. Herein, we also demonstrate the utility of the stage in (i) studying the wrinkling process and (ii) fabricating complex wrinkled patterns that are inaccessible via other techniques. Specifically, we demonstrate that (i) spatial nonuniformity in the patterns is limited to 6.5%, (ii) one-dimensional (1D) single-period wrinkles of nominal period 2.3 μm transition into the period-doubled mode when the compressive strain due to prestretch release of plasma-oxidized polydimethylsiloxane (PDMS) film exceeds ∼18%, and (iii) asymmetric two-dimensional (2D) wrinkles can be fabricated by tuning the strain state and/or the actuation path, i.e., the strain history. Thus, this tensile stage opens up the design space for fabricating and tuning complex wrinkled patterns and enables extracting empirical process knowledge via in situ visualization of wrinkle formation.

In this paper, we present the design, analysis, and testing of an ankle rehabilitation device (ARD), the purpose of which is to improve the efficacy of ankle joint complex (AJC) injury diagnosis and treatment. The ARD enables physicians to quantitatively measure the severity of an injury. This is done by measuring deficiencies in the joint’s range of motion, as well as force, torque, and power output. Evaluation of the relative degree of recovery over time can also reduce the error associated with current methodologies for rehabilitation, which rely on measurements based on the patient’s verbal response. A Wheatstone bridge circuit is used for the measurement of the various parameters as applied to the blades of complementary rotational flexures; the device is designed to measure motion about three axes of rotation in the ankle joint: pitch, roll, and yaw. A full bridge circuit is applied to each axis of rotation, and the use of multiple axes increases anatomically accurate measurement, enabling characterization of coupled motions. The device has flexibility and a range of motion such that it can be adjusted to take measurements of multiple different degrees of plantar or dorsiflexion of the AJC. The ARD is able to measure both range of motion, force, and torque output simultaneously. Experimental results show that there is significant coupled motion among the ankle joint rotations but that it is highly dependent on a subject’s own physical development.

Carbon nanotubes (CNTs) may be used to create nanoscale compliant mechanisms that possess large ranges of motion relative to their device size. Many macroscale compliant mechanisms contain compliant elements that are subjected to fixed-clamped boundary conditions, indicating that they may be of value in nanoscale design. The combination of boundary conditions and large strains yield deformations at the tube ends and strain stiffening along the length of the tube, which are not observed in macroscale analogs. The large-deflection behavior of a fixed-clamped CNT is not well-predicted by macroscale large-deflection beam bending models or truss models. Herein, we show that a pseudo-rigid-body model may be adapted to capture the strain stiffening behavior and, thereby, predict a CNT’s fixed-clamped behavior with less than 3% error from molecular simulations. The resulting pseudo-rigid-body model may be used to set initial design parameters for CNT-based compliant mechanisms. This removes the need for iterative, time-intensive molecular simulations during initial design phases.

A flexure-based ankle rehabilitation device utilizes the linear elastic force-deflection characteristics of certain types of flexure beams to measure the forces and torques output by the human ankle joint complex (AJC). Three sets of flexures, placed so as to allow rotation about the three primary rotational axes of the AJC, allow for a measurement of all three major rotations applied by the ankle joint and coupled motions essential for walking, balancing, and running. Currently, there is no method or universally accepted device used to measure and quantify the strength, speed, and stabilizing ability of the AJC. This is especially important when it is considered that ankle injuries are perhaps the most common type of musculoskeletal injury. Furthermore, AJC integrity is recognized as critical to the maintenance of balance and prevention of falls among older adults. We have developed a device that would primarily be used by physicians or rehabilitative professionals as part of a more standardized methodology of musculoskeletal care and to determine the extent of an ankle’s recovery after injury. It has potential to help researchers better understand the recovery process and the mechanics of ankle injuries. Additionally, it could be useful to the footwear and orthopedic industries as a means of evaluating products for AJC protection and recovery. The architecture of the device could also be modified to fit other multi-DOF joints, such as the wrist, shoulder, hip, or spine. Single-DOF devices could also be developed to potentially increase efficacy of rehabilitation practices for single-DOF joints such as the knee and the elbow. Upon fulfilling its initial functional requirements, this device still has a lot of potential for further development. The current design can be tuned fairly easily by exchanging different flexure modules of varying stiffness. This allows for testing of different materials, stiffness values, and flexure module designs. Furthermore, it would be possible to expand on the design so that it can be used as a training tool, instead of just as an evaluation device. A rehabilitation program utilizing such a device would serve to isolate the ankle much more than current recovery exercises, helping to reduce the chances of re-injury. Current technology used to evaluate ankle rehabilitation focuses solely either on the foot’s range of motion or on the joint’s ability to balance the rest of the body. While the former ignores the ankle strength, the latter disregards any information regarding the ankle beyond the standing configuration. The flexure-based ankle rehabilitation device measures ankle strength and power output through a range of motion that is anatomically similar to walking, running, etc. Also, measuring power output is not feasible with currently available devices and is believed to be very important for further injury prevention. Also, a wide range of foot configurations can be achieved, suggesting that regardless of the patient’s physical abilities, the device can still be used to safely and effectively rehabilitate a person’s injured joint and return it to a healthy state. Results from the initial prototype suggest that an ankle rehabilitation device utilizing compliant mechanisms can measure the expected torque outputs from the ankle joint. Use of compliant mechanisms allows for the design of a more cost-effective, compact device that can be handled by physicians even outside of a hospital setting. The final paper will present the second design iteration and the results of measurements that will be performed on patients’ rehabilitating ankles in the interim so as to determine what other adjustments need to be made in the system to account for the coupled motions of the ankle joint. A full working system including data acquisition equipment utilized to collect patient information and the final device iteration will be presented in the final technical paper.

This paper focuses on the design and implementation of a percutaneous catheter-based device to provide physicians with an externally controlled tool capable of manipulating and cutting specific chordae tendinae within the heart to alleviate problems associated with some forms of mitral valve (MV) regurgitation. In the United States alone, approximately 500,000 people develop ischemic or functional mitral regurgitation per year. Many of these patients do not possess the required level of health necessary to survive open-heart surgery, and the development of a chordal cutting procedure and device is needed to allow these patients to receive treatment. A deterministic design process was used to generate several design concepts and then evaluate and compare each concept based on a set of functional requirements. A final concept to be alpha prototyped was then chosen, further developed, and fabricated. Experiments showed that the design was capable of locating and grabbing a chord and that ultrasound imaging is a viable method for navigating the device inside of the human body. Once contact between the chord and radio-frequency (RF) ablation tip was confirmed, the chord was successfully ablated.