Expanding research impact through engaging the maker community and collaborating with digital content creators.

This paper proposes a method for increasing the impact of academic research by providing materials for public use, thus engaging the maker community, and by collaborating with internet content creators to extend the reach. We propose a framework for engagement and report a multi-year study that evaluates short, intermediate, and long-term outcomes, with a second effort to demonstrate repeatability of the short-term outcomes. In the first study, we posted forty-one 3D printable compliant mechanisms on public repositories and collaborated with physicist and content creator Derek Muller (Veritasium YouTube channel). Outputs and outcomes from this interaction were measured over 3 years. The framework was exercised again with four new 3D printable mechanisms in collaboration with engineer and STEM influencer Mark Rober. The proposed methods aim to help researchers extend the reach of their work to broader audiences, including professional engineers, hardware designers, educators, students, researchers, and hobbyists. This work demonstrates promising impacts of the framework, including (1) extending public awareness of research findings to broader audiences by engaging the maker community and collaborating with content creators, (2) accelerating the pace of innovation and further hardware-based research through public application of research findings, (3) fostering a culture of open-source design and collaboration among other researchers, engineers, educators, and makers, and (4) increasing utilization of peer-reviewed published content. These outreach practices can be valuable tools for researchers to increase impact of and excitement for their research.

Transgene delivery via intracellular electroporetic nanoinjection.

Development of an effective cytoplasmic delivery technique has remained an elusive goal for decades despite the success of pronuclear microinjection. Cytoplasmic injections are faster and easier than pronuclear injection and do not require the pronuclei to be visible; yet previous attempts to develop cytoplasmic injection have met with limited success. In this work we report a cytoplasmic delivery method termed intracellular electroporetic nanoinjection (IEN). IEN is unique in that it manipulates transgenes using electrical forces. The microelectromechanical system (MEMS) uses electrostatic charge to physically pick up transgenes and place them in the cytoplasm. The transgenes are then propelled through the cytoplasm and electroporated into the pronuclei using electrical pulses. Standard electroporation of whole embryos has not resulted in transgenic animals, but the MEMS device allows localized electroporation to occur within the cytoplasm for transgene delivery from the cytoplasm to the pronucleus. In this report we describe the principles which allow localized electroporation of the pronuclei including: the location of mouse pronuclei between 21 and 28 h post-hCG treatment, modeling data predicting the voltages needed for localized electroporation of pronuclei, and data on electric-field-driven movement of transgenes. We further report results of an IEN versus microinjection comparative study in which IEN produced transgenic pups with viability, transgene integration, and expression rates statistically comparable to microinjection. The ability to perform injections without visualizing or puncturing the pronuclei will widely benefit transgenic research, and will be particularly advantageous for the production of transgenic animals with embryos exhibiting reduced pronuclear visibility.

Nanoinjection: pronuclear DNA delivery using a charged lance.

We present a non-fluidic pronuclear injection method using a silicon microchip "nanoinjector" composed of a microelectromechanical system with a solid, electrically conductive lance. Unlike microinjection which uses fluid delivery of DNA, nanoinjection electrically accumulates DNA on the lance, the DNA-coated lance is inserted into the pronucleus, and DNA is electrically released. We compared nanoinjection and microinjection side-by-side over the course of 4 days, injecting 1,013 eggs between the two groups. Nanoinjected zygotes had significantly higher rates of integration per injected embryo, with 6.2% integration for nanoinjected embryos compared to 1.6% integration for microinjected embryos. This advantage is explained by nanoinjected zygotes' significantly higher viability in two stages of development: zygote progress to two-cell stage, and progress from two-cell stage embryos to birth. We observed that 77.6% of nanoinjected zygotes proceeded to two-cell stage compared to 54.7% of microinjected zygotes. Of the healthy two-cell stage embryos, 52.4% from the nanoinjection group and 23.9% from the microinjected group developed into pups. Structural advantages of the nanoinjector are likely to contribute to the high viability observed. For instance, because charge is used to retain and release DNA, extracellular fluid is not injected into the pronucleus and the cross-sectional area of the nanoinjection lance (0.06 µm(2)) is smaller than that of a microinjection pipette tip (0.78 µm(2)). According to results from the comparative nanoinjection versus microinjection study, we conclude that nanoinjection is a viable method of pronuclear DNA transfer which presents viability advantages over microinjection.

An ultra-wideband origami microwave absorber.

Microwave absorbers have been used to mitigate signal interference, and to shield electromagnetic systems. Two different types of absorbers have been presented: (a) low-cost narrowband absorbers that are simple to manufacture, and (b) expensive wideband microwave absorbers that are based on complex designs. In fact, as designers try to increase the bandwidth of absorbers, they typically increase their complexity with the introduction of several electromagnetic components (e.g., introduction of multi-layer designs, introduction of multiple electromagnetic resonators, etc.,), thereby increasing their fabrication cost. Therefore, it has been a challenge to design wideband absorbers with low cost of fabrication. To address this challenge, we propose a novel design approach that combines origami math with electromagnetics to develop a simple to manufacture ultra-wideband absorber with minimal fabrication and assembly cost. Specifically, we utilize a Tachi-Miura origami pattern in a honeycomb configuration to create the first absorber that can maintain an absorptivity above 90% in a 24.6:1 bandwidth. To explain the ultra-wideband behavior of our absorber, we develop analytical models based on the transmission-reflection theory of electromagnetic waves through a series of inhomogeneous media. The ultra-wideband performance of our absorber is validated and characterized using simulations and measurements.

Origami-inspired systems that improve adult diaper performance to enhance user dignity.

This paper proposes a novel origami-inspired adult diaper design that improves discretion by reducing sag and increasing wicking across the entire diaper pad. While other diapers rely on supporting elastics to reduce the sag of the diaper as a whole, this paper proposes an absorbent core that uses liquid activated shaping to take a specified shape. Origami-based folds are also incorporated into the diaper design to increase wicking performance. The paper introduces a disposable compliant mechanism waistband used to deploy the diaper, making it easier to put onto one's body.

Developable mechanisms on developable surfaces.

The trend toward smaller mechanism footprints and volumes, while maintaining the ability to perform complex tasks, presents the opportunity for exploration of hypercompact mechanical systems integrated with curved surfaces. Developable surfaces are shapes that a flat sheet can take without tearing or stretching, and they represent a wide range of manufactured surfaces. This work introduces "developable mechanisms" as devices that emerge from or conform to developable surfaces. They are made possible by aligning hinge axes with developable surface ruling lines to enable mobility. Because rigid-link motion depends on the relative orientation of hinge axes and not link geometry, links can take the shape of the corresponding developable surface. Mechanisms are classified by their associated surface type, and these relationships are defined and demonstrated by example. Developable mechanisms show promise for meeting unfilled needs using systems not previously envisioned.

Creating Linkage Permutations to Prevent Self-Intersection and Enable Deployable Networks of Thick-Origami.

Origami concepts show promise for creating complex deployable systems. However, translating origami to thick (non-paper) materials introduces challenges, including that thick panels do not flex to facilitate folding and the chances for self-intersection of components increase. This work introduces methods for creating permutations of linkage-based, origami-inspired mechanisms that retain desired kinematics but avoid self-intersection and enable their connection into deployable networks. Methods for reconfiguring overconstrained linkages and implementing them as modified origami-inspired mechanisms are proved and demonstrated for multiple linkage examples. Equations are derived describing the folding behavior of these implementations. An approach for designing networks of linkage-based origami vertices is demonstrated and applications for tessellations are described. The results offer the opportunity to exploit origami principles to create deployable systems not previously feasible.

Bistable Mechanisms for Space Applications.

Compliant bistable mechanisms are monolithic devices with two stable equilibrium positions separated by an unstable equilibrium position. They show promise in space applications as nonexplosive release mechanisms in deployment systems, thereby eliminating friction and improving the reliability and precision of those mechanical devices. This paper presents both analytical and numerical models that are used to predict bistable behavior and can be used to create bistable mechanisms in materials not previously feasible for compliant mechanisms. Materials compatible with space applications are evaluated for use as bistable mechanisms and prototypes are fabricated in three different materials. Pin-puller and cutter release mechanisms are proposed as potential space applications.

Packing and deploying Soft Origami to and from cylindrical volumes with application to automotive airbags.

Packing soft-sheet materials of approximately zero bending stiffness using Soft Origami (origami patterns applied to soft-sheet materials) into cylindrical volumes and their deployment via mechanisms or internal pressure (inflation) is of interest in fields including automobile airbags, deployable heart stents, inflatable space habitats, and dirigible and parachute packing. This paper explores twofold patterns, the 'flasher' and the 'inverted-cone fold', for packing soft-sheet materials into cylindrical volumes. Two initial packing methods and mechanisms are examined for each of the flasher and inverted-cone fold patterns. An application to driver's side automobile airbags is performed, and deployment tests are completed to compare the influence of packing method and origami pattern on deployment performance. Following deployment tests, two additional packing methods for the inverted-cone fold pattern are explored and applied to automobile airbags. It is shown that modifying the packing method (using different methods to impose the same base pattern on the soft-sheet material) can lead to different deployment performance. In total, two origami patterns and six packing methods are examined, and the benefits of using Soft Origami patterns and packing methods are discussed. Soft Origami is presented as a viable method for efficiently packing soft-sheet materials into cylindrical volumes.

Rigidly foldable origami gadgets and tessellations.

Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented.

A self-reconfiguring metamorphic nanoinjector for injection into mouse zygotes.

This paper presents a surface-micromachined microelectromechanical system nanoinjector designed to inject DNA into mouse zygotes which are ≈90 µm in diameter. The proposed injection method requires that an electrically charged, DNA coated lance be inserted into the mouse zygote. The nanoinjector's principal design requirements are (1) it must penetrate the lance into the mouse zygote without tearing the cell membranes and (2) maintain electrical connectivity between the lance and a stationary bond pad. These requirements are satisfied through a two-phase, self-reconfiguring metamorphic mechanism. In the first motion subphase a change-point six-bar mechanism elevates the lance to ≈45 µm above the substrate. In the second motion subphase, a compliant folded-beam suspension allows the lance to translate in-plane at a constant height as it penetrates the cell membranes. The viability of embryos following nanoinjection is presented as a metric for quantifying how well the nanoinjector mechanism fulfills its design requirements of penetrating the zygote without causing membrane damage. Viability studies of nearly 3000 nanoinjections resulted in 71.9% of nanoinjected zygotes progressing to the two-cell stage compared to 79.6% of untreated embryos.

A standardized representation of spinal quality of motion.

The experimentally determined torque-rotation curve of the lumbar spine is mathematically described with a proposed dual-inflection point Boltzmann equation. The result is a method for describing functional spinal unit motion data. The benefit of the model is that each of the coefficients has a specific meaning in relation to the torque-rotation curve: the points A and B identify the respective minimum and maximum rotations of the functional spinal unit, m1 and m2 indicate the inflection points of the curve where the stiffness changes markedly, and α1 and α2 are associated with the rates of change of the curve at m1 and m2, respectively. The dual-inflection point Boltzmann captures the full quality of motion of the spinal segment and can also be used to derive relevant parameters such as range of motion, midrange stiffness, and hysteresis.

Characterization and prediction of rate-dependent flexibility in lumbar spine biomechanics at room and body temperature.

BACKGROUND CONTEXT: The soft tissues of the spine exhibit sensitivity to strain-rate and temperature, yet current knowledge of spine biomechanics is derived from cadaveric testing conducted at room temperature at very slow, quasi-static rates. PURPOSE: The primary objective of this study was to characterize the change in segmental flexibility of cadaveric lumbar spine segments with respect to multiple loading rates within the range of physiologic motion by using specimens at body or room temperature. The secondary objective was to develop a predictive model of spine flexibility across the voluntary range of loading rates. STUDY DESIGN: This in vitro study examines rate- and temperature-dependent viscoelasticity of the human lumbar cadaveric spine. METHODS: Repeated flexibility tests were performed on 21 lumbar function spinal units (FSUs) in flexion-extension with the use of 11 distinct voluntary loading rates at body or room temperature. Furthermore, six lumbar FSUs were loaded in axial rotation, flexion-extension, and lateral bending at both body and room temperature via a stepwise, quasi-static loading protocol. All FSUs were also loaded using a control loading test with a continuous-speed loading-rate of 1-deg/sec. The viscoelastic torque-rotation response for each spinal segment was recorded. A predictive model was developed to accurately estimate spine segment flexibility at any voluntary loading rate based on measured flexibility at a single loading rate. RESULTS: Stepwise loading exhibited the greatest segmental range of motion (ROM) in all loading directions. As loading rate increased, segmental ROM decreased, whereas segmental stiffness and hysteresis both increased; however, the neutral zone remained constant. Continuous-speed tests showed that segmental stiffness and hysteresis are dependent variables to ROM at voluntary loading rates in flexion-extension. To predict the torque-rotation response at different loading rates, the model requires knowledge of the segmental flexibility at a single rate and specified temperature, and a scaling parameter. A Bland-Altman analysis showed high coefficients of determination for the predictive model. CONCLUSIONS: The present work demonstrates significant changes in spine segment flexibility as a result of loading rate and testing temperature. Loading rate effects can be accounted for using the predictive model, which accurately estimated ROM, neutral zone, stiffness, and hysteresis within the range of voluntary motion.

Intervertebral disc degeneration alters lumbar spine segmental stiffness in all modes of loading under a compressive follower load.

BACKGROUND CONTEXT: Previous studies have investigated the relationship between the degeneration grade of the intervertebral disc (IVD) and the flexibility of the functional spinal unit (FSU) but were completed at room temperature without the presence of a compressive follower load. This study builds on previous work by performing the testing under more physiological conditions of a compressive follower load at body temperature and at near 100% humidity. PURPOSE: The present work evaluates the effects of IVD degeneration on segmental stiffness, range of motion (ROM), hysteresis area, and normalized hysteresis (hysteresis area/ROM). This study also briefly evaluates the effect of the segment level, temperature, and follower load on the same parameters. STUDY DESIGN: In vitro human cadaveric biomechanical investigation. METHODS: Twenty-one FSUs were tested in the three primary modes of loading at both body temperature and room temperature in a near 100% humidity environment. A compressive follower load of 440 N was applied to simulate the physiological conditions. Fifteen of the 21 segments were also tested without the follower load to determine the effects of the follower load on segmental biomechanics. The grade of degeneration for each segment was determined using the Thompson scale, and the torque-rotation curves were fit with the Dual-Inflection-Point Boltzmann sigmoid curve. RESULTS: Intervertebral disc degeneration resulted in statistically significant changes in segmental stiffness, ROM, and hysteresis area in axial rotation (AR) and lateral bending (LB) and statistically significant changes in ROM and normalized hysteresis in flexion-extension (FE). The progression of these changes with increased degeneration is nonlinear, with changes in the FE and LB tending to respond in concert and opposite to the changes in AR. The lumbosacral joint was significantly stiffer and demonstrated a decreased ROM and hysteresis area as compared with other lumbar segments in AR and LB. Temperature had a significant effect on the stiffness and hysteresis area in AR and on the hysteresis area in LB. Application of a compressive follower load increased the stiffness in all three modes of loading but was significant only in AR and LB. It also reduced the ROM and increased normalized hysteresis in all three modes of loading. CONCLUSIONS: The results from this testing quantify the effects of degeneration on spinal biomechanics. Because the testing was conducted under physiological conditions (including a compressive follower load and at body temperature), we expect the measured response to closely match the in vivo response. The testing results can be used to guide the selection of appropriate surgical treatments in the context of IVD degeneration and to validate the mathematical and engineering models of the lumbar spine, including finite element models.

A compliant-mechanism approach to achieving specific quality of motion in a lumbar total disc replacement.

BACKGROUND: The current generation of total disc replacements achieves excellent short- and medium-term results by focusing on restoring the quantity of motion. Recent studies indicate that additional concerns (helical axes of motion, segmental torque-rotation behavior) may have important implications in the health of adjacent segments as well as the health of the surrounding tissue of the operative level. The objective of this article is to outline the development, validation, and biomechanical performance of a novel, compliant-mechanism total disc replacement that addresses these concerns by including them as essential design criteria. METHODS: Compliant-mechanism design techniques were used to design a total disc replacement capable of replicating the moment-rotation response and the location and path of the helical axis of motion. A prototype was evaluated with the use of bench-top testing and single-level cadaveric experiments in flexion-extension, lateral bending, and axial torsion. RESULTS: Bench-top testing confirmed that the moment-rotation response of the disc replacement matched the intended design behavior. Cadaveric testing confirmed that the moment-rotation and displacement response of the implanted segment mimicked those of the healthy spinal segment. CONCLUSIONS: Incorporation of segmental quality of motion into the foundational stages of the design process resulted in a total disc replacement design that provides torque-rotation and helical axis-of-motion characteristics to the adjacent segments and the operative-level facets that are similar to those observed in healthy spinal segments.