Second-generation Prototype Research Articles

In Vivo Testing of a Second-Generation Prototype Accessory for Single Transapical Left Ventricular Assist Device Implantation.

A new accessory was developed to allow implantation of left ventricular assist devices (LVADs) without requiring an anastomosis to the ascending aorta. The accessory combines the LVAD inflow and outflow into a dual-lumen device. Initial prototypes encountered reduced pump performance in vitro, but a second-generation prototype successfully addressed this issue. This feasibility study aimed to demonstrate the anatomic fit, safe implantation, and hemodynamic effectiveness of the LVAD with the accessory. The accessory was implanted in ten female pigs (104 ± 13 kg). Following sternotomy and apical coring under cardiopulmonary bypass, a balloon catheter was retrogradely inserted and exteriorized through the coring site, where it was inflated within the distal third of the outflow graft. It was utilized to pull the accessory's outflow across the aortic valve. After LVAD attachment, the catheter was removed. Echocardiography revealed no relevant valve regurgitation post-implantation. During ramp testing, pump flow increased from 3.7 ± 1.2 to 5.4 ± 1.2 L/min. Necropsy confirmed correct accessory placement in nine animals. No valve lesions or device thrombosis were observed. The accessory enabled LVAD implantation without compromising pump performance. Future work includes design refinements for implantation without cardiopulmonary bypass and long-term testing in a chronic heart failure model.

Initial Clinical Images From a Second-Generation Prototype Silicon-Based Photon-Counting Computed Tomography System

To demonstrate the feasibility andpotential of using a second-generation prototype photon-counting computed tomography (CT) system to provide simultaneous high spatial resolution images and high spectral resolution material information across a range of routine imaging tasks using clinical patient exposure levels. The photon-counting system employs an innovative silicon-based photon-counting detector to provide a balanced approach to ultra-high-resolution spectral CT imaging. An initial cohort of volunteer subjects was imaged using the prototype photon-counting system. Acquisition technique parameters and radiation dose exposures were guided by routine clinical exposure levels used at the institution. Images were reconstructed in native slice thickness using an early version of a spectral CT reconstruction algorithm Samples of images across a range of clinical tasks were selected and presented for review. Clinical cases are presented across inner ear, carotid angiography, chest, and musculoskeletal imaging tasks. Initial reconstructed images illustrate ultra-high spatial resolution imaging. The fine detail of small structures and pathologies is clearly visualized, and structural boundaries are well delineated. The prototype system additionally provides concomitant spectral information with high spatial resolution. This initial study demonstrates that routine imaging at clinically appropriate patient exposure levels is feasible using a novel deep-silicon photon-counting detector CT system. Furthermore, a deep-silicon detector may provide a balanced approach to photon-counting CT, providing high spatial resolution imaging with simultaneous high-fidelity spectral information.

A precision-designed gastrostomy button securement device

BackgroundGastrostomy buttons (g-buttons) are commonly placed in children to facilitate weight gain, correct nutritional deficiencies, and provide hydration and/or medication delivery. At our institution, parents are taught to place a gauze sponge under their child's g-button and secure it with strips of tape; however, the g-button still moves in the tract, which delays wound healing and leads to a variety of tract-related complications. We viewed this universal problem as a challenge and a prime opportunity for innovation. MethodsIn 2016, a pediatric surgeon and a team of graduate engineering students outlined the problem, created a list of design requirements, and began to iterate on a variety of device designs. ResultsOver 400 design ideas were iterated upon to various degrees. The first prototype was studied in a small clinical trial, in which 80% of caregivers reported satisfaction with the design, but 90% noted difficulty connecting the extension feeding tube. A second-generation prototype was developed, which included a reusable lid and disposable base layer. Third- generation prototypes added “edge-grippers” to facilitate attaching the extension tubing, plus pre-cut absorbent, sterile gauze pads to fit around the stem of the g-button. Finally, in 2020, the design was finalized with the addition of a childproof hinge between the lid and base layer. ConclusionsAn intuitive g-button securement device was created to simplify daily gauze replacement, reduce tract-related complications, and lower the cost of care. A randomized controlled trial comparing the securement device to the “tic-tac-toe” dressing will begin in early 2022 with results available later this year.

A system for automated acquisition of digital flexion using a 3-D camera and custom gantry.

Automated measurement of digital range of motion (ROM) may improve the accuracy of reporting and increase clinical efficiency. We hypothesize that a 3-D camera on a custom gantry will produce ROM measurements similar to those obtained with a manual goniometer. A 3-D camera mounted on a custom gantry, was mechanized to rotate 200° around a platform. The video was processed to segment each digit and calculate joint angles in people with no history of any hand conditions or surgery to validate the system. A second-generation prototype was then assessed in people with different hand conditions. Metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joint flexion were measured repeatedly with a goniometer and the automated system. The average difference between manual and automatic measurements was calculated along with intraclass correlation coefficients (ICC). In the initial validation, 1,488 manual and 1,488 automated joint measurements were obtained and the measurement algorithm was refined. In people with hand conditions, 688 manual and 688 automated joint measurements were compared. Average acquisition time was 7s per hand, with an additional 2-3s required for data processing. ICC between manual and automated data in the clinical study ranged from 0.65 to 0.85 for the MCP joints, and 0.22 to 0.66 for PIP joints. The automated system resulted in rapid data acquisition, with reliability varying by type of joint and location. It has the potential to improve efficiency in the collection of physical exam findings. Further developments of the system are needed to measure thumb and distal phalangeal motions.

A Spatiotemporal Microenvironment Model to Improve Design of a Three-Dimensional Bioreactor for Red Cell Production.

Cellular microenvironments provide stimuli, including paracrine and autocrine growth factors and physicochemical cues, which support efficient in vivo cell production unmatched by current in vitro biomanufacturing platforms. While three-dimensional (3D) culture systems aim to recapitulate niche architecture and function of the target tissue/organ, they are limited in accessing spatiotemporal information to evaluate and optimize in situ cell/tissue process development. Herein, a mathematical modeling framework is parameterized by single-cell phenotypic imaging and multiplexed biochemical assays to simulate the nonuniform tissue distribution of nutrients/metabolites and growth factors in cell niche environments. This model is applied to a bone marrow mimicry 3D perfusion bioreactor containing dense stromal and hematopoietic tissue with limited red blood cell (RBC) egress. The model characterized an imbalance between endogenous cytokine production and nutrient starvation within the microenvironmental niches and recommended increased cell inoculum density and enhanced medium exchange, guiding the development of a miniaturized prototype bioreactor. The second-generation prototype improved the distribution of nutrients and growth factors and supported a 50-fold increase in RBC production efficiency. This image-informed bioprocess modeling framework leverages spatiotemporal niche information to enhance biochemical factor utilization and improve cell manufacturing in 3D systems. Impact statement Three-dimensional (3D) culture systems are becoming increasingly important because they recapitulate the architecture and, consequently, physiological function of the target tissue/organ. Design and optimization of these 3D biomanufacturing platforms require evaluation of in situ spatiotemporal information. We have developed an integrated experimental-computational framework that captures the spatiotemporal distribution of cells, nutrients, and cytokines within a marrow biomimicry perfusion bioreactor. The model simulated biochemical factor utilization and guided the design of an improved second-generation bioreactor that achieved 50-fold increase in RBC production with improved cost efficiency. Such a modeling framework provides an essential platform for the optimization of 3D biomanufacturing systems.

Optimizing correction of coma aberration in keratoconus with a novel soft contact lens

PurposeTo report on a second-generation prototype contact lens (modified lens) with enhanced optics to correct coma aberration and compare its performance with that of the prototype contact lens (conventional lens) used to optimise correction of coma aberration in keratoconus (KC). MethodsBoth lenses were designed as a set of standardised soft contact lenses (SCLs) with asymmetric powers along the posterior surface. The modified lens differs from the conventional lens in that the optical zone is decentred superiorly by 0.7 mm. The on-eye performance was compared between the SCLs and no-lens wearing in terms of manifest refraction, corrected distance visual acuity (CDVA), ocular aberrations, subjective quality of vision, and on-eye lens position relative to the pupil. ResultsThirty-four KC eyes were included. SCLs significantly decreased coma aberration compared to no-lens wear (none, 0.68 ± 0.27 μm; conventional lens, 0.37 ± 0.28 μm; modified lens, 0.19 ± 0.15 μm; P < 0.001), with the reduction in coma aberration being significantly greater with the modified lens than with the conventional lens (P = 0.018). No significant difference in manifest refraction or CDVA was found among the three conditions. Quality of vision was significantly better with the modified lens than with no SCL wear (P < 0.05) but no differences were found between the SCLs. The on-eye optical center position relative to the pupil was closer to the pupil centre using the modified lens than the conventional lens (P < 0.001). ConclusionOptimisation of the location of the optical zone in a standardised asymmetric SCL improves correction of coma aberrations and on-eye optical centration.

A novel multi-study intervention investigating the short and long term effects of a posture bra on whole body and breast kinematics

BackgroundPoor standing posture has been reported in women with larger breasts, increasing the risk of back pain. Whilst breast reduction surgery can improve posture, conservative measures such as special bras may offer short or long-term relief of symptoms without surgical intervention. Research questionThis study aimed to utilise a multi-study intervention to investigate the short and long-term kinematic effects of wearing a posture bra. MethodsStudy one utilised biomechanics and physiotherapy expertise to modify the design of a prototype bra to improve posture and breast kinematics; resulting in a second-generation posture bra. To test this bra, 24 females were randomly assigned to control and intervention groups. The control group wore their everyday bra; the intervention group wore the generation 2 posture bra in place of their everyday bra for three months. Pre and post intervention, posture (spine curvature, scapula position, whole body alignment) and breast kinematics were assessed during sitting, standing and walking. Short-term effects of the posture bra were compared to an everyday bra and no bra (study two), whilst the long-term effects were compared using the no bra condition (study three). ResultsBiomechanical intervention improved posture and breast kinematics in a prototype posture bra resulting in a second-generation prototype. Pre-intervention, the generation 2 posture bra significantly improved scapula retraction by 6° during both sitting and standing, but also increased deviation of whole body alignment compared to everyday bra and no bra conditions. During walking the posture bra reduced breast motion by 17 % compared to the everyday bra. Following the three-month wearer intervention, scapula depression significantly improved in the intervention group. SignificanceA biomechanically informed posture bra was able to effectively support the breasts and improve scapula position without compromising spinal curvature, reducing the risk of musculoskeletal pain associated with poor posture.

Active Vertical Takeoff of an Aquatic UAV

To extend the mission duration of smaller unmanned aerial vehicles, this letter presents a solar recharge approach that uses lakes as landing, charging, and standby areas. The Sherbrooke University Water-Air VEhicle (SUWAVE) is a small aircraft capable of vertical takeoff and landing on water. A second-generation prototype has been developed with new capabilities: solar recharging, autonomous flight, and a larger takeoff envelope using an actuated takeoff strategy. A 3D dynamic model of the new takeoff maneuver is conceived to understand the major forces present during this critical phase. Numerical simulations are validated with experimental results from real takeoffs made in the laboratory and on lakes. The final prototype is shown to have accomplished repeated cycles of autonomous takeoff, followed by assisted flight and landing, without any human physical intervention between cycles.

Second generation prototype of a variable stiffness transverse plane adapter for a lower limb prosthesis

The prescription and fitting of a traditional lower limb prosthesis often focuses on straight walking, neglecting maneuvers such as turning and pivoting that require flexibility in the transverse plane. Current devices that allow transverse plane movement only offer a fixed stiffness and are incapable of adapting to varying daily activities. Pilot testing of a first-generation variable stiffness torsion adapter (VSTA I) showed a benefit for individuals with lower limb amputation by reducing peak transverse plane moments at the residual limb which could lead to increased comfort, but testing was limited due to excessive device height and mass. The VSTA II, a second-generation prototype, is capable of discrete stiffness variation from 0.31 to 1.29 Nm/° in 0.25 Nm/° increments with ±30° of motion in addition to fully locked operation. Stiffness variation is enabled by five independent spring subunits that can be combined in parallel to create different, linear, stiffness settings. The VSTA II features a reduced mass (51% reduction) and height (42% reduction) compared to its predecessor along with a tether-free controller and power system. These improvements will permit greater recruitment for amputee studies, and allow for advanced testing both in and out of the lab.

Investment analysis of marine cage culture by applying bioeconomic reference points: A case study of the spotted rose snapper (Lutjanus guttatus) in Mexico

ABSTRACTIn Mexico, marine finfish cage culture is envisioned as an economic alternative for coastal fishermen. Because research and outreach have not yet proved that this is profitable, assessing the investment through financial risk assessment and setting reference points for expected outcomes is useful. For Lutjanus guttatus, this research reports on a 10-year investment analysis of a pilot-scale, ongrowing four-cage module tested in Mazatlán, Mexico that incorporated a) hatchery-reared fry, b) species-specific feed and c) a second-generation prototype cage, all of them results of almost a decade of research. Two production scenarios were examined: Scenario I, with a high survival rate (90%–95%) and a low feed conversion ratio (FCR) (1.4–1.7), and Scenario II, with a low survival rate (67%–75%) and a high FCR (1.8–2.0). The net present value results are positive for Scenario I (mean = US$134,709, and a 95% probability interval (PI) [US$91,621; US$176,436]) and negative for Scenario II (mean = US-$79,082, 95% PI [US-$116,140; US-$42,054]). To identify feasibility improvement, reference points (threshold values) for survival, FCR, fry and feed costs were determined.

A Dual Image Sensor Approach for Automated, High Resolution, Region-of-Interest Imaging in a 96-Well Plate

Phenotypic screens are performed on model organisms to understand how chemical compounds affect biological systems. High-throughput devices are needed to efficiently gather large volumes of data for these screens. Recently we developed a low cost high-throughput imaging solution to capture the effects of chemicals on the egg-laying behaviour of C. elegans. We present a second-generation prototype capable of high-resolution (0.2 µm/px) imaging of individual worms and their internal structures. It features an automatic real time segmentation of C. elegans worms and is compatible with 96-well plates. In order to maximize efficiency in data collection, we developed an approach for simultaneous dual imaging through a single objective. A low-resolution (15 µm/px) arm continuously collects images of an entire well using a CCD camera (1280 px by 1024 px). The images are continuously fed into a Python image algorithm that tracks the movement of the worms in regions of interest (ROIs). Using this information, high resolution images of the worms are captured using a linescan camera (8000 px). This solution provides automated high-resolution imaging minimizing acquisition time by eliminating the need for multiple objectives, allowing image collection with a continuously moving system (high speed linescan camera) and minimizing the amount of stitching (large linescan sensor). The scan time of a 96-well plate is proportional to the number of ROIs, which is significantly less than imaging an entire plate. The high-resolution images can be fed into an image processing pipeline that will be able to classify the effects of chemicals on the internal structure of the worms. Simultaneous acquisition of high and low resolution data can be used to correlate deformations of internal structure with changes in mobility. This low cost solution provides users with an automated approach to obtain high-resolution images and mobility statistics of C. elegans.

Preliminary performance characterization of DbPET2.1, a PET scanner dedicated to the imaging of the breast and extremities

The combined effort of several laboratories at our institution resulted in the building of the first high-resolution PET/CT prototype dedicated to imaging the extremities of the body. Ongoing clinical trials for breast-cancer diagnosis and assessment of the response to treatment underlined the need for a second-generation prototype with improved electronics and spatial resolution. A preliminary version has been assembled and fully characterized. In this work, we present further improvements in detector performance, as well as the readout electronics for the PET component. The detector consists of a 16 × 16 array of 1.27 × 1.27 × 20 mm3 lutetium yttrium orthosilicate crystals, the smallest crystal size for completed breast PET prototypes to date, directly coupled to a position-sensitive photomultiplier tube (PSPMT). The scintillator crystals are polished on all six faces and separated by a ∼70 μm enhanced specular reflector. The readout electronics were redesigned to reduce their footprint and improve timing resolution. We report a detector energy and timing resolution of 12% and 1.0 ns, respectively, and an average intrinsic spatial resolution of 1.29 mm (central row in one detector array). The new PET/CT has been fully assembled, and initial system characterization is being performed. We report a system energy resolution of 15.7%, a timing resolution of 1.5 ns and a filtered back-projection image spatial resolution in the center of the field of view of 1.6 mm.

A Fluidic Colorimetric Sensor Design for Water Hardness Detection

A new sensor design for detecting water hardness using complexometric and colorimetric concepts is presented in this paper. Calmagite, a metal ion indicator, changes color of a solution to wine red in presence of calcium (Ca <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ) and magnesium (Mg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ) ions at pH 10. Ethylenediaminetetraacetic acid (EDTA) displaces the indicator from the metal-indicator complex after it is added to a solution and turns it blue. A red solution is transparent to a red light whereas nontransparent to a blue light and vice versa. A photodiode placed across the solution will give out a reading of voltage (V) variation across the diode depending on the amount of red or blue light passing through the solution and striking the photodiode. A sensor prototype is 3D printed with a channel embedded in it to hold water sample. Water hardness is detected based on visual inspection of color change of the sample and voltage change occurring when calmagite and EDTA are mixed to the sample. For a first-generation prototype, voltage variation of ~30% and 13% for blue light and 6% and 74% in average for red light in comparison to the baseline, i.e., when neither calmagite nor EDTA is mixed to the water sample, is observed due to color change. Then, a second-generation prototype is printed, which shows improvement in voltage readings compared with the first generation. Transmittance and absorbance of the solution are computed using the voltage variation data recorded across the photodiodes. A calibration curve is then compiled by measuring absorbance of various concentrations of standard CaCO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> solution, which is then used to predict the water hardness type of the water sample.

Demand for the Early Detection of Diabetic Risk at Annual Health Examinations and A Probable Solution

Despite medical examinations, the number of cases of undiagnosed diabetes has reached 17.9 million. Hence, there is a strong need for diagnostic criteria that uses proper biomarkers at annual health examinations, even in developing countries. Recently, we developed a second-generation prototype of a multimarker analysis system that facilitates a rapid assay of a single, small-volume sample for numerous biomarkers. Clinicians may be able to manage and/or advise subjects regarding their food and exercise habits before the onset of diabetes by evaluating their biomarker levels using this system. We have begun 5 years of cohort testing to evaluate these multibiomarkers.

In-car game design for children: Promoting interactions inside and outside the car

Abstract Long car rides can become a source of boredom for children, consequently causing tension inside the car. Common solutions against boredom include entertainment devices suitable for in-car use. Such devices often disengage children from other family members inside the car, as well as from the outside world. We set out to create a novel in-car game that connects children with their family and their environment, instead of only their entertainment devices. The game, called Mileys, integrates location-based information, augmented reality and virtual characters. We developed Mileys in an iterative process — findings from the first round of prototyping and evaluation guided the design of a second-generation prototype and lead to additional evaluations. In this paper we discuss lessons learned during the development and evaluation of Mileys, present challenges for location-based in-car game design, and suggest potential solutions for promoting interactions inside and outside the car.

Integrative advances for OCT-guided ophthalmic surgery and intraoperative OCT: microscope integration, surgical instrumentation, and heads-up display surgeon feedback.

PurposeTo demonstrate key integrative advances in microscope-integrated intraoperative optical coherence tomography (iOCT) technology that will facilitate adoption and utilization during ophthalmic surgery.MethodsWe developed a second-generation prototype microscope-integrated iOCT system that interfaces directly with a standard ophthalmic surgical microscope. Novel features for improved design and functionality included improved profile and ergonomics, as well as a tunable lens system for optimized image quality and heads-up display (HUD) system for surgeon feedback. Novel material testing was performed for potential suitability for OCT-compatible instrumentation based on light scattering and transmission characteristics. Prototype surgical instruments were developed based on material testing and tested using the microscope-integrated iOCT system. Several surgical maneuvers were performed and imaged, and surgical motion visualization was evaluated with a unique scanning and image processing protocol.ResultsHigh-resolution images were successfully obtained with the microscope-integrated iOCT system with HUD feedback. Six semi-transparent materials were characterized to determine their attenuation coefficients and scatter density with an 830 nm OCT light source. Based on these optical properties, polycarbonate was selected as a material substrate for prototype instrument construction. A surgical pick, retinal forceps, and corneal needle were constructed with semi-transparent materials. Excellent visualization of both the underlying tissues and surgical instrument were achieved on OCT cross-section. Using model eyes, various surgical maneuvers were visualized, including membrane peeling, vessel manipulation, cannulation of the subretinal space, subretinal intraocular foreign body removal, and corneal penetration.ConclusionsSignificant iterative improvements in integrative technology related to iOCT and ophthalmic surgery are demonstrated.

Development of the Novel Embedded Planetary-Screw Extruder

The novel second-generation embedded planetary-screw extruder prototype was successfully developed in the paper which had eight small planetary-screws and had the excellent degassing function. The numerical simulation of the three-dimensional flow and mixing in the metering zone was carried out for different screw configurations to determine the effect of the number of the small planetary-screws using CFD finite volume method technology. We improved the screw combination of the second-generation prototype according to the simulation results as well as the experimental investigations on first-generation embedded planetary-screw extruder we developed some years ago. The second-generation prototype can effectively improve the axial transport capacity and increase output of the extruder when compared with the first-generation prototype. The novel second-generation prototype can expand the scope of application and can improve the quality of processing material. The novel embedded planetary-screw extruders have a better application prospect.

Marine floating microbial fuel cell involving aerobic biofilm on stainless steel cathodes

Here is presented a new design of a floating marine MFC in which the inter-electrode space is constant. This design allows the generation of stable current for applications in environments where the water column is large or subject to fluctuations such as tidal effects. The operation of the first prototype was validated by running a continuous test campaign for 6months. Performance in terms of electricity generation was already equivalent to what is conventionally reported in the literature with basic benthic MFCs despite the identification of a large internal resistance in the proposed design of the floating system. This high internal resistance is mainly explained by poor positioning of the membrane separating the anode compartment from the open seawater. The future objectives are to achieve more consistent performance and a second-generation prototype is now being developed, mainly incorporating a modification of the separator position and a stainless steel biocathode with a large bioavailable surface.

Design and fabrication of a bat-inspired flapping-flight platform using shape memory alloy muscles and joints

This work focuses on the development of a concept for a micro-air vehicle (MAV) based on a bio-inspired flapping motion that is generated from integrated smart materials. Since many smart materials have their own biomimetic characteristics and the potential to be highly efficient, lightweight, and streamlined, they are ideal candidates for use in structural or actuator components in MAVs. In this work, shape memory alloy (SMA) actuator wires are used as analogs for biological muscles, and super-elastic SMAs are implemented as flexible joints capable of large bending angles. While biological organisms have an intrinsic sensing array composed of nerves, the SMA wires also provide self-sensing by virtue of a phase-dependent resistance change. Study of the biology and flight characteristics of natural fliers concluded that the bat provides an ideal platform for SMA muscle wires because of its comparatively low wingbeat frequency and superb maneuverability. A first-generation prototype is built to further the understanding of fabricating Nature’s designs. The engineering design is then improved further in a second-generation prototype that combines 3D printing and new techniques for embedding SMA wires and shaping SMA joints for improved robustness, reproducibility, and lifetime. These prototypes are on display at the North Carolina Museum of Natural Science’s Nature Research Center, which has the goal of bridging the gaps between biology and engineering.

BAND-LIMITED CORONAGRAPHS USING A HALFTONE-DOT PROCESS. II. ADVANCES AND LABORATORY RESULTS FOR ARBITRARY TELESCOPE APERTURES

The band-limited coronagraph is a nearly ideal concept that theoretically enables perfect cancellation of all the light of an on-axis source. Over the past years, several prototypes have been developed and tested in the laboratory, and more emphasis is now on developing optimal technologies that can efficiently deliver the expected high-contrast levels of such a concept. Following the development of an early near-IR demonstrator, we present and discuss the results of a second-generation prototype using halftone-dot technology. We report improvement in the accuracy of the control of the local transmission of the manufactured prototype, which was measured to be less than 1%. This advanced H-band band-limited device demonstrated excellent contrast levels in the laboratory, down to 10-6 at farther angular separations than 3 lambda/D over 24% spectral bandwidth. These performances outperform the ones of our former prototype by more than an order of magnitude and confirm the maturity of the manufacturing process. Current and next generation high-contrast instruments can directly benefit from such capabilities. In this context, we experimentally examine the ability of the band-limited coronagraph to withstand various complex telescope apertures.