Benchtop Testing Research Articles

Design and Validation of a Soft Robotic Simulator for Transseptal Puncture Training.

Transseptal puncture (TP) is the technique used to access the left atrium of the heart from the right atrium during cardiac catheterization procedures. Through repetition, electrophysiologists and interventional cardiologists experienced in TP develop manual skills to navigate the transseptal catheter assembly to their target on the fossa ovalis (FO). Cardiology fellows and cardiologists that are new to TP currently train on patients to develop this skill, resulting in increased risk of complications. The goal of this work was to create low-risk training opportunities for new TP operators. We developed a Soft Active Transseptal Puncture Simulator (SATPS), designed to match the dynamics, static response, and visualization of the heart during TP. The SATPS includes three subsystems: (i) A soft robotic right atrium with pneumatic actuators mimics the dynamics of a beating heart. (ii) A fossa ovalis insert simulates cardiac tissue properties. (iii) A simulated intracardiac echocardiography environment provides live visual feedback. Subsystem performance was verified with benchtop tests. Face and content validity were evaluated by experienced clinicians. Subsystems accurately represented atrial volume displacement, tenting and puncture force, and FO deformation. Passive and active actuation states were deemed suitable for simulating different cardiac conditions. Participants rated the SATPS as realistic and useful for training cardiology fellows in TP. The SATPS can help improve catheterization skills of novice TP operators. The SATPS could provide novice TP operators the opportunity to improve their TP skills before operating on a patient for the first time, reducing the likelihood of complications.

Performance of Position, Force, and Impedance Controllers for a Pneumatic Cylinder Ankle Exoskeleton

Abstract The best exoskeleton control strategy depends on the task, motivating the development and analysis of an exoskeleton capable of position, force, and impedance control. In this paper, we implement and compare the three controller types via sliding mode control on a custom-built pneumatic cylinder ankle exoskeleton. To evaluate each controller's performance, the exoskeleton was tested on the benchtop and with human subject experiments. With the position controller, the exoskeleton achieved an root-mean-square error (RMSE) of under 5 deg for both the benchtop and human tests. It had a bandwidth of approximately 12 rad/s. The force controller tracked sinusoidal trajectories acceptably well at low frequencies (15% of force range at 6 rad/s), with a bandwidth of approximately 24 rad/s. The error was significantly higher (RMSE of 24% of force range) for the more biologically relevant trajectory. The impedance controller demonstrated the desired spring-like behavior, with position RMSE generally under 5 deg compared to expected position. All three controllers worked equally well for benchtop and human tests. Thus, a pneumatically powered ankle exoskeleton with sliding mode control is capable of accurate position and impedance control and is capable of marginally acceptable force control.

Benchtop impaction device replicates cadaveric loading conditions of the transforaminal lumbar interbody fusion (TLIF) procedure

Background contextLumbar spine disc pathologies often necessitate removal of the intervertebral disc and implantation of a lumbar interbody fusion (LIF) device. Herein, the objective was to measure use condition forces while simulating intra-operative loading conditions of transforaminal lumbar interbody fusion (TLIF) procedures. MethodsIn this work, we developed a transferable method to measure impact forces in a cadaveric intra-operative setting and designed a drop weight benchtop device equipped with force and displacement sensors to replicate cadaveric impact conditions, including number of strikes required for interbody device insertion, peak force, initial slope of the impact waveform, impact duration, and area under the force-time curve (impulse). Following cadaveric testing, a benchtop biomechanical study varying interbody device height, drop height, and drop weight was performed to evaluate the utility of the benchtop device to replicate impact loading conditions which occurred in the cadaveric model. ResultsSeveral benchtop test groups replicated the cadaver group in number of strikes required for device insertion. The average cadaveric peak force, 13.03 kN, was replicated by three benchtop groups: 12 mm device height, 60 cm drop height, 0.75 lb drop weight; 12 mm device height, 60 cm drop height, 1.0 lb drop weight; and 14 mm device height, 60 cm drop height, 0.50 lb drop weight. The initial slope of the impact waveform was replicated best by 12 mm devices. Both the impact duration and impulse were lower in all benchtop groups than in cadaver testing. ConclusionsThis work validated the outfitting of an impact force sensor onto an interbody device insertion instrument as a reproducible, quantifiable method for collecting impact loading data in a cadaveric model. This benchtop device and methodology will aid in testing interbody devices relative to anticipated use conditions, enhance interbody device designs, and accelerate surgical technique refinement.

Design and preliminary evaluation of a lower limb exoskeleton based on hydraulic actuator

PurposeThis paper aims to propose a novel system design and control algorithm of lower limb exoskeleton, which provides walking assistance and load sharing for the wearer.Design/methodology/approachIn this paper, the valve-controlled asymmetrical hydraulic cylinder is selected for driving the hip and knee joint of exoskeleton. Pressure shoe is developed that purpose on detecting changes in plantar force, and a fuzzy recognition algorithm using plantar pressure is proposed. Dynamic model of the exoskeleton is established, and the sliding mode control is developed to implement the position tracking of exoskeleton. A series of prototype experiments including benchtop test, full assistance, partial assistance and loaded walking experiments are set up to verify the tracking performance and power-assisted effect of the proposed exoskeleton.FindingsThe control performance of PID control and sliding mode control are compared. The experimental data shows the tracking trajectories and tracking errors of sliding mode control and demonstrate its good robustness to nonlinearities. sEMG of the gastrocnemius muscle tends to be significantly weakened during assisted walking.Originality/valueIn this paper, a structure that the knee joint and hip joint driven by the valve-controlled asymmetrical cylinder is used to provide walking assistance for the wearer. The sliding mode control is proposed to deal with the nonlinearities during joint rotation and fluids. It shows great robustness and frequency adaptability through experiments under different motion frequencies and assistance modes. The design and control method of exoskeleton is a good attempt, which takes positive impacts on the productivity or quality of the life of wearers.

The effect of current and lambda on white-etch-crack failures

White etching cracks (WECs) have been associated with premature failure of wind turbine roller bearings. Various drivers for the generation of WECs have been identified such as loading conditions, slip, steel quality, lubrication, hydrogen embrittlement, corrosion fatigue cracking, and stray electrical currents passing through the surface. In this work, a benchtop test rig utilizing a three-ring-on-roller test configuration was used to investigate the effect of electrical current and operation in different lubricating regimes, defined by lambda (λ), on high-quality bearing steel samples tested in a commercially available power transmission EP gear lubricant. It was observed that there is an inverse correlation between the magnitude of electric current applied to the ring/roller system and time-to-failure. Higher current magnitudes lead to shorter time-to-failure than lower current magnitudes, with macropitting as the main failure mode. Sub-surface investigation revealed the presence of WECs in all cases. For the same current magnitude, tests conducted in boundary and mixed lubrication regimes showed that time-to-failure increased as λ increased, and the tests resulted in WEC related macropits, whereas tests conducted in near-hydrodynamic regime resulted in surface damage with no macropit. It was also noted that a shift toward near-hydrodynamic lubrication resulted in a distinct surface distress on the roller surface. Furthermore, there seems to be a transition in the mixed regime during which the surface distress occurred. The damage on the surface of the test samples resembled non-spatially, periodic, groove-like corrugations and, in some cases, crater-like depressions. Sub-surface imaging, performed by sequential sectioning, revealed the presence of WECs in all cases, and broad, branching cracks that were more prevalent under the more severe boundary conditions.

Energy Deposition on Analogous Vehicle Panel: Thermal–Structural Response

A proof-of-concept experimental methodology and results are presented for the simulation of direct thermal energy deposition on a hypersonic vehicle panel analog. The methodology involved uniformly heating ceramic plates via joule heating with localized regions of thermal nonuniformity achieved via plate profiling. A parametric study was first performed to quantify the key parameters governing the level of simulated energy deposition achieved. The plate material, profile size, and amperage used to energize the plate were varied in this study, with a total of 108 cases analyzed. The overall plate thermal response, the achieved over the profile section, and the plate deflection were examined in detail. Configurations resulting in high overall plate temperatures with large in the profile section and appreciable deflection were then selected for benchtop testing. Wall temperatures in the range of 686–1144 K were achieved experimentally with peak T in the range of 46–427 K. One plate was visually observed to deflect on the order of 3 mm. The results from this demonstrate the suitability of the presented methodology for generating nonuniform, yet controlled temperature profiles on analogous vehicle panels for future shock-tunnel testing.

An interdigitated capacitive sensor for early detection of contrast media extravasation

Contrast Media Extravasation (CMEV) is a well-known complication of intravenous administration of contrast media during computed tomography (CT) scans. It refers to the leakage of contrast media from the blood vessel into the surrounding soft tissues. As contrast media are vesicant solutions, extravasation can result in the development of adverse side effects such as erythema, tissue necrosis, and compartment syndrome. Therefore, there is an urgent clinical need to develop a device that can detect extravasation early and minimize the severity of extravasation injuries. In this work, we present a cost-effective and wearable sensor patch to aid in the early detection of extravasation via capacitive sensing. The technical feasibility of the proposed sensor was then evaluated through a series of bench-top tests and ex-vivo tests. The results showed that the sensor patch is able to distinguish between normal contrast media administration and contrast media extravasation scenarios. Our proposed sensor has shown potential for early detection of CMEV, with a decrease in capacitance being a promising indicator of extravasation. This sensor also has the potential to reduce the occurrence of extravasation events in the hospital, especially for patients at risk of extravasation. Future work includes optimizing the sensor and validating it through a clinical trial to bring it a step closer to actual commercial use.

(Invited) 3D-Printed Epidermal Microfluidic Systems for the Collection and Analysis of Sweat

An emerging class of wearable devices integrates microfluidic lab-on-chip designs with low-modulus materials, colorimetric assays, and electrochemical sensors to support the real-time, non-invasive analysis of sweat. Such skin-interfaced microfluidic systems offer powerful capabilities for personalized assessment of health, nutrition, and wellness through the non-invasive, real-time analysis of sweat. Initially simple systems of microfluidic channels, current devices comprise sophisticated networks channels, valves, and reservoirs with some embodiments employing multilayer design strategies. While these platforms exhibit powerful analytical capabilities, device fabrication requires time, labor, and resource-intensive cleanroom processing, which restricts the device design space (2D) and elongates the development time. Additive manufacturing processes, particularly stereolithography (SLA)-based printing, offer powerful pathways for overcoming these limitations by providing significant reductions in prototype development cost and cycle time while substantially expanding device capabilities with fully 3D device designs. Here, we present a simplified 3D-printing prototyping process to fabricate flexible, stretchable, epidermal microfluidic devices (‘3D-epifluidics’). Reducing fabrication time to [O]min, this approach enables the integration of spatially-engineered features including 3D-structured passive capillary valves, monolithic channels, and reservoirs with spatially-graded geometries. With geometric features comparable to established epifluidic devices (channels >50 μm), benchtop and on-body testing validate the performance of 3D-epifluidic devices.

Accelerated in vitro oxidative degradation testing of polypropylene surgical mesh.

Polypropylene (PP) surgical mesh had reasonable success in repair of hernia and treatment of stress urinary incontinence (SUI); however, their use for the repair of pelvic organ prolapse (POP) resulted in highly variable results with lifelong complications in some patients. One of several factors that could be associated with mesh-related POP complications is changes in the properties of the implanted surgical mesh due to oxidative degradation of PP in vivo. Currently, there are no standardized in vitro bench testing methods available for assessing the susceptibility to oxidative degradation and estimating long-term in vivo stability of surgical mesh. In this work, we adapted a previously reported automated reactive accelerated aging (aRAA) system, which uses elevated temperatures and high concentrations of hydrogen peroxide (H2 O2 ), for accelerated bench-top oxidative degradation testing of PP surgical mesh. Since H2 O2 is highly unstable at elevated temperatures and for prolonged periods, the aRAA system involves a feedback loop based on electrochemical detection methods to maintain consistent H2 O2 concentration in test solutions. Four PP mesh samples with varying mesh knit designs, filament diameter, weight, and % porosity, were selected for testing using aRAA up to 4 weeks and characterized using thermal analysis, Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM). Additionally, the oxidation index (OI) values were calculated based on the FTIR-ATR spectra to estimate the oxidative degradation and oxidation reaction kinetics of PP surgical mesh. The OI values and surface damage in the form of surface flaking, peeling, and formation of transverse cracks increased with aRAA aging time. The aRAA test method introduced here could be used to standardize the assessment of long-term stability of surgical mesh and may also be adopted for accelerated oxidative degradation testing of other polymer-based medical devices.

In-silico modelling of multi-strike insertion and torsional resistance of tapered revision hip stems: Insight into spline design philosophy.

Despite the clinical success of tapered splined titanium stems, a knowledge gap still exists between spline design and its primary mechanical stability, which is critical to the long-term success of revision hip arthroplasty. Additionally, almost all published pre-clinical studies relied on resource-intensive benchtop and cadaveric testing. Hence, the present study developed a novel computational model to investigate effects of spline geometry and configuration on axial and torsional stability of tapered stem. Dynamic explicit Finite Element Analysis coupled with a state-of-the-art adaptive meshing technique was used to simulate the highly non-linear contacts and large bony material deformations. Hybridising primary straight splines with secondary angled splines results in 41% and 10% increases of peak insertion force and post-seating moment than the predicate device for the same seating position. The primary straight splines cut at multiple circumferential bony locations, enhancing torsional stability; while the alternatively placed secondary angled splines form wedges with the bone, providing reliable seating and additional torsional resistance. To the best knowledge of the author, this is the first in-silico investigation of its kind to simulate multi-strike seating and torsional resistance of revision hip stems, offering an effective and efficient platform for future multi-factorial parametric study and uncertainty quantification.

Preclinical cardiac perforation reduction in leadless pacing: An update to the Micra leadless pacemaker delivery system.

Leadless pacemakers have been developed to avoid some of the complications that are associated transvenous pacemakers. Pericardial effusion is a rare complication of leadless pacemaker implantation, which may result from perforation of the delivery catheter. In this study, we describe preclinical perforation performance of an updated Micra delivery catheter. To assess preclinical perforation performance of the updated delivery catheter, three analyses were performed. First, Finite Element Analysis (FEA) computational modeling was performed to estimate the target tissue stress during Micra delivery catheter tenting. Second, benchtop perforation forces of ovine tissue were recorded for the original and updated delivery catheters. Finally, a Monte-Carlo simulation combining human cadaveric Micra implant forces and human ventricular tissue perforation properties was performed to estimate clinical perforation performance. FEA modeling demonstrated a 66% reduction in target tissue stress when using the updated Micra delivery catheter (6.2vs. 2.2psi, Original vs. Updated Micra delivery catheter). Updated Micra delivery catheters required 20% more force to perforate porcine ventricular tissues in benchtop testing (μupd =26.9N vs. μorg =22.4N, p=.01). Monte-Carlo Simulation of catheter performance in human cadaveric tissues predicts 28.5% reduction of catheter-perforated cases with the updated delivery catheter. This study, using computer modelling and benchtop experimentation, has indicated that increased surface area and rounding of the updated Micra catheter tip significantly improves preclinical perforation performance. It will be important to evaluate the impact of these catheter design changes with robust registry data.

Evaluating the Efficiency of Magnetic Treatment for Feed Water in Reverse Osmosis Processes.

The paper presents a new methodology for short-term (5-25 min) benchtop tests to evaluate the effectiveness of magnetic treatment of feed water for reducing mineral scaling on a reverse osmosis (RO) membrane. Scale deposition is measured at a controlled level of salt supersaturation in water flowing through an RO unit in once-through mode. A magnetic water conditioner is tested in a transient flow regime when variations of the permeate flux along the flow path are insignificant. Scale formation under these conditions is governed by salt crystallization on the membrane surface. The proposed method was implemented to investigate the influence of magnetic treatment on gypsum deposition on RO membranes in supersaturated aqueous CaSO4/NaCl solutions. The effects of magnetic water treatment on scale formation under our experimental conditions were found to be statistically insignificant with a confidence level of 95%. However, this outcome should not be considered to negate the potential efficiency of magnetic water treatment in specific applications. The proposed methodology of testing under a controlled level of salt supersaturation will also be useful for evaluating the efficiency of other water treatment technologies.

Walatimine (Vanillyl Butyl Imine): A New Ketimine from Schiff Base Synthesis and Evaluation of its Antioxidant, Antibacterial and Antifungal Properties

Background of study: Vanillin is a white crystalline compound which is a phenolic aldehyde with a balsamic flavour. It is widely obtained from vanilla bean-pods amongst very many other sources. This compound and some of its derivatives possess diverse activities including anticancer, anti- inflammatory, antioxidant, antibacterial and antifungal amongst others. Hence, the import of this study. Objectives: The growing concerns about the deleterious actions of free radical oxygenated species (FROS) in the human body have become a huge concern to the scientific world. These chemical species continually devastate the human cells, tissues and organs leading to different pathophysiological conditions and neurodegenerative disorders. Also, the noticeable microbial resistance to antibiotics and antifungal drugs have prompted the search for lead compound(s) with the aim of chemically modifying its/their molecular structure(s) or synthesizing other compounds from reactions involving them such as Schiff base synthesis. The search for novel pharmaceutically active compounds with the aim of ameliorating these conditions led to the choice of vanillin. Methodology: Vanillin was subjected to the Schiff base synthesis. It was reacted separately with amines (aromatic and aliphatic amine) leading to the bases in the presence of acid. The melting points, refractive indices and optical rotations of the vanillin and the Schiff bases were obtained. The antioxidant activity (IC50) of the lead compound and bases was determined employing the DPPH (2, 2-diphenyl-1-picrylhydrazyl hydrate) bench-top assay test. Comparison of the obtained antioxidant activities was done to determine if any improvements could be noticed in the synthesized bases. Also, the agar-in-hole diffusion method was adopted for screening vanillin and the synthesized bases against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeriginosa and Candida albicans for antibacterial and antifungal activities respectively. Results: The identities of the synthesized Schiff bases have been revealed to be vanillyl butyl imine (W) a new ketimine referred to by the trivial name- Walatimine and vanillin-2,4-dinitrophenyl hydrazone (Vdnp) respectivelyusing a combination of physico-chemical determinations and IR spectral technique. Vanillin and (W) demonstrated marginal antioxidant activity of IC50 of 0.52 and 0.50 μg/mL respectively while Vdnp gave a remarkably significant IC50 of 0.48 and which compare favourably with 0.46 μg/mL elicited by Vitamin C (a standard antioxidant drug). The antibacterial and antifungal activities elicited by both W and Vdnp were concentration dependent. Furthermore, Vdnp was comparably more bacteriostatic than W against the test bacteria though it was inactive against Ps. aeriginosa. However, vanillyl butyl imine (W) was slightly more anti-candidal against C. albicans than vanillin-2,4-dinitrophenyl hydrazone (Vdnp). Conclusion: The results from this study indicate that vanillin-2,4- dinitrophenyl hydrazone (Vdnp) obtained from the condensation reaction of vanillin and an aromatic amine affords a comparably better antioxidant activity than W obtained from vanillin reacting with an aliphatic amine. Both W and Vdnp demonstrated remarkable antibacterial and antifungal activities hence, these two synthesized Schiff bases can be lead candidate compounds in the search for newer and more efficacious antioxidant and antimicrobial agents and in further structural activity relationship studies (SARS) and as well as in formulation studies in drug development.

A hybrid soft material robotic end-effector for reversible in-space assembly of strut components.

Based on the NASA in-Space Assembled Telescope (iSAT) study (Bulletin of the American Astronomical Society, 2019, 51, 50) which details the design and requirements for a 20-m parabolic in-space telescope, NASA Langley Research Center (LaRC) has been developing structural and robotic solutions to address the needs of building larger in-space assets. One of the structural methods studied involves stackable and collapsible modular solutions to address launch vehicle volume constraints. This solution uses a packing method that stacks struts in a dixie-cup like manner and a chemical composite bonding technique that reduces weight of the structure, adds strength, and offers the ability to de-bond the components for structural modifications. We present in this paper work towards a soft material robot end-effector, capable of suppling the manipulability, pressure, and temperature requirements for the bonding/de-bonding of these conical structural components. This work is done to investigate the feasibility of a hybrid soft robotic end-effector actuated by Twisted and Coiled Artificial Muscles (TCAMs) for in-space assembly tasks. TCAMs are a class of actuator which have garnered significant recent research interest due to their allowance for high force to weight ratio when compared to other popular methods of actuation within the field of soft robotics, and a muscle-tendon actuation design using TCAMs leads to a compact and lightweight system with controllable and tunable behavior. In addition to the muscle-tendon design, this paper also details the early investigation of an induction system for adhesive bonding/de-bonding and the sensors used for benchtop design and testing. Additionally, we discuss the viability of Robotic Operating System 2 (ROS2) and Gazebo modeling environments for soft robotics as they pertain to larger simulation efforts at LaRC. We show real world test results against simulation results for a method which divides the soft, continuous material of the end-effector into discrete links connected by spring-like joints.

Pre-Implantation Bovine Embryo Evaluation—From Optics to Omics and Beyond

Approximately 80% of the ~1.5 million bovine embryos transferred in 2021 were in vitro produced. However, only ~27% of the transferred IVP embryos will result in live births. The ~73% pregnancy failures are partly due to transferring poor-quality embryos, a result of erroneous stereomicroscopy-based morphological evaluation, the current method of choice for pre-transfer embryo evaluation. Numerous microscopic (e.g., differential interference contrast, electron, fluorescent, time-lapse, and artificial-intelligence-based microscopy) and non-microscopic (e.g., genomics, transcriptomics, epigenomics, proteomics, metabolomics, and nuclear magnetic resonance) methodologies have been tested to find an embryo evaluation technique that is superior to morphologic evaluation. Many of these research tools can accurately determine embryo quality/viability; however, most are invasive, expensive, laborious, technically sophisticated, and/or time-consuming, making them futile in the context of in-field embryo evaluation. However accurate they may be, using complex methods, such as RNA sequencing, SNP chips, mass spectrometry, and multiphoton microscopy, at thousands of embryo production/collection facilities is impractical. Therefore, future research is warranted to innovate field-friendly, simple benchtop tests using findings already available, particularly from omics-based research methodologies. Time-lapse monitoring and artificial-intelligence-based automated image analysis also have the potential for accurate embryo evaluation; however, further research is warranted to innovate economically feasible options for in-field applications.

P107: In Vitro, Benchtop Testing Indicates Improved Hemocompatibility with a New Magnetically Levitated VAD

Purpose: Ventricular assist devices (VADs) improve heart failure outcomes, yet the challenge of reducing bleeding, stroke, and infection persists. Biomarkers related to these adverse events were evaluated with a next-generation, totally magnetically suspended (TMS) VAD in comparison to other blood pumps. Method: Bovine whole blood or human plasma was circulated through benchtop flow loops with an Abbott CentriMag (CM) or HeartMate II (HMII), or a CH Biomedical USA BrioVAD (N = 5 tests). Flows were maintained at 4.5 L/min against an afterload of 75 mmHg. Samples were collected hourly for 6 hours. Plasma free hemoglobin was measured by spectroscopy. Normalized index of hemolysis (NIH) was calculated as described in ASTM F1841-19. VWF function (VWF:CB/Ag) was quantified using VWF:CB and VWF:Ag assay kits; VWF multimer distribution was determined using agarose-gel electrophoresis and in-gel immunofluorescent staining. Statistical significance was determined using an ANOVA (NIH) or regression analysis (VWF:CB/Ag) followed by a post-hoc Tukey test for significance between specific devices. Results: The CM and BrioVAD exhibited significantly lower hemolysis than the HMII (NIH: BrioVAD = 0.006 g/100L, CM = 0.002 g/100L, HMII = 0.029 g/100L; p < 0.01). The BrioVAD preserved VWF function after 6 hours compared to both HMII and CM (Fig. 1; VWF:CB/Ag, 6 h: BrioVAD = 94% retained, CM = 75%, HMII = 74%; p < 0.01). Similarly, the BrioVAD preserved a greater percentage of high molecular weight multimers (HMWM) than HMII and CM (BrioVAD = 96%, CM = 84%, HMII = 76%) with a higher ratio of HMWM to low molecular weight multimers (LMWM) (HMWM/LMWM: BrioVAD = 1.69, CM = 1.22, HMII = 1.09). Conclusion: Both the BrioVAD and CM achieved lower hemolysis than the HMII. However, the BrioVAD alone preserved VWF function and HMWM better than the CM and HMII. The inference that magnetically levitated centrifugal pumps are more hemocompatible than axial flow pumps with mechanical bearings is supported. The observation of improved In Vitro hemocompatibility with a newer magnetically levitated pump is encouraging and warrants further study.Figure 1. VWF function measured over the course of 6 hours.

CARD7: Design of a Hybrid Wireless Left Ventricular Assist Device with a New Charging System

Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and limiting the outside activities of patients, thereby reducing the quality of life of patients. Transcutaneous Energy Transfer Systems (TETSs) have been developed to solve these problems but they have other problems such as malposition between coils and burn injury due to sending high-power transmission. In a previous study, we proposed a new concept of wireless LVAD, which consisted of magnetic and electric pumps, to improve the current problems of conventional wireless LVAD. However, implanting two different pumps in the body could occupy more space than a single pump. In addition, two extracorporeal devices on the skin, an external coil for TETS and extracorporeal rotating magnets for the magnetic pump, were possibly confusing to patients. Moreover, the distance limitation between the extracorporeal magnets and intrathoracic pump remained a fundamental problem of the magnetic pump. To solve these problems, we developed a single hybrid pump driven by either magnetic or electric force and charged wirelessly without an external coil. Our new wireless LVAD was a hybrid pump operating in two different modes: magnetic and electric modes. The pump was driven wirelessly by extracorporeal rotating magnets in magnetic mode, whereas it was driven by electricity from an intracorporeal battery in electric mode. Magnetic torque transmission system was introduced to efficiently transmit magnetic torque to the impeller. The intracorporeal battery was charged in magnetic mode making use of electromagnetic coils as a generator, which operated as a motor in electric mode. Our hybrid pump performed a flow rate and a head pressure of approximately 5.0 L/min and 80 mm Hg, respectively, in a bench-top test. The charging rate of the intracorporeal battery in magnetic mode was around 2.5 W, which enabled the hybrid pump to operate in electric mode 3 hours a day. Magnetic torque transmission system shortened the distance between the extracorporeal and intracorporeal magnets and achieved downsizing the magnets. Our hybrid wireless LVAD solved the potential problems of our previous wireless LVAD and demonstrated a new wireless charging system without an external coil. It has the potential to reduce the problems relating to drivelines and to realize high quality of life of patients with LAVD. Our future prospect is to conduct an in vivo test with our device.Figure 1. Prospective configuration of our hybrid LVAD system: (A) intracorporeal components, (B) positional relationship between the hybrid pump and extracorporeal device.Figure 2. (A) Top view of the impeller, (B) Bottom view of the impeller, (C) Pump housing, (D) Hybrid pumpFigure 3. (A) Front view of the test loop, (B) detailed view of the hybrid pump and extracorporeal magnets

(506) Histology Appears to Reveal Good Sealing of the Human, Porcine and Dog Vasectomy Specimens using the Vasectomy Sealing Procedure

Abstract Introduction The Sealed Vasectomy Procedure (SVP) is a new bipolar radiofrequency sealing tool for transdermal vasectomy in hopes of making the procedure a faster, simpler, and safer office procedure. Testing has been successful in rabbits with excellent wound healing, complete vas occlusion on histology, and no sperm in post-procedural semen analysis. The study data was presented last year as a video submission and subsequently won the AUA 2022’s “Best Video” of the andrology / infertility / sexual dysfunction session. Further studies in larger animals were indicated and FDA approval is needed before its application in humans. The issue of “does the SVP effectively seal the vas deferens in animals larger than a rabbit and in humans?” is a critical one for treating physicians. Objective Evaluate the effectiveness of the SVP in sealing the vas deferens in animals larger than a rabbit and in humans. Methods Animal (rabbit) studies have been previously described. We performed microscopic evaluation of the vas deferens tissues from canines treated with the SVP at either 40 or 60 watts, euthanized at 14 days post-treatment under the conditions of this study. Human vas deferens specimens after removal from the patient were then immediately treated with SVP tool on benchtop. Porcine vas deferens samples were procured and underwent benchtop testing. Specimens were sent for pathologic evaluation by a third-party professional vendor [Crisp County Regional Medical Center in Cordele, Georgia]. Results 4 canine, 6 human, and 26 porcine vas deferens were included in SVP testing. Human, porcine, and canine specimens demonstrated tissue coagulation and fibrosis in the treated vasa deferentia. (See Figure 1 Human and 2 Canine) Conclusions SVP is a potentially exciting novel vasectomy procedure that appears to provide good sealing of the vas deferens in the canine animal model and on benchtop for the human and porcine vas deferens. FDA approval is still needed before use in humans. Disclosure Yes, this is sponsored by industry/sponsor: Signati Medical Clarification Industry initiated, executed and funded study Any of the authors act as a consultant, employee or shareholder of an industry for: Signati Medical.

Development of High-Entropy Alloy (HEA) Anode for Carbon-Free and Electrochemically-Stable Operation of SOFC on Hydrocarbon Fuels

High-entropy alloy (HEA) anode, consisting of multicomponent alloy and gadolinium-doped ceria (GDC) powders, were synthesized and evaluated for ethanol steam reforming under SOFC operating conditions using a fixed-bed reactor as well as electrochemical performance using a button cell test configuration. Both bench-top and cell tests were conducted at 700 °C with a steam-to-carbon (S/C) ratio of 2. While Ni anode showed filamentary carbon formation, and performance degradation with time, HEA/GDC catalyst showed stable performance without carbon deposition. As an anode, HEA/GDC demonstrated high electrochemical stability and comparable current density compared to the Ni electrode.

On the Benefits and Limitations of Modulated Damping With Passive Motor Control

Abstract Conventional emulated damping, in which velocity feedback is employed in combination with motor current control to emulate damping, is used in a number of mechatronic applications. As known in the field, although such damping should be strictly passive, several implementation factors render this emulation nonpassive and subject to instability, especially with increasing damping ratios. This paper describes an alternative implementation of emulated damping that employs passive motor control, which does not draw energy from a battery or any other power source. The method is specifically described in the context of a brushless direct-current (BLDC) motor; an unique controller architecture is used along with a particular MOSFET switching scheme which employs only a subset of the standard BLDC motor driver and does not require electronic commutation. This paper employs analytical and experimental means to compare damping control with the described passive motor approach, relative to using a conventional BLDC motor control approach. Stability considerations for each scheme are discussed. Benchtop testing demonstrates the advantage of the passive control scheme in terms of providing smooth behavior, enhancing control robustness, preventing energy leaks, and providing accurate behavior. The special cases of unilateral and asymmetric behaviors (i.e., different damping command for each direction of rotation) are also considered.