Flexible Silicone Tube Research Articles

Shortwave Infrared Imaging of a Quantum Dot-Based Magnetic Guidewire Toward Non-Fluoroscopic Peripheral Vascular Interventions.

Peripheral vascular interventions (PVIs) offer several benefits to patients with lower extremity arterial diseases, including reduced pain, simpler anesthesia, and shorter recovery time, compared to open surgery. However, to monitor the endovascular tools inside the body, PVIs are conducted under X-ray fluoroscopy, which poses serious long-term health risks to physicians and patients. Shortwave infrared (SWIR) imaging of quantum dots (QDs) has shown great potential in bioimaging due to the non-ionizing penetration of SWIR light through tissues. In this paper, a QD-based magnetic guidewire and its system is introduced that allows X-ray-free detection under SWIR imaging and precise steering via magnetic manipulation. The QD magnetic guidewire contains a flexible silicone tube encapsulating a QD polydimethylsiloxane (PDMS) composite, where HgCdSe/HgS/CdS/CdZnS/ZnS/SiO2 core/multi-shell QDs are dispersed in the PDMS matrix for SWIR imaging upon near-infrared excitation, as well as a permanent magnet for magnetic steering. The SWIR penetration of the QD magnetic guidewire is investigated within an artificial tissue model (1% Intralipid) and explore the potential for non-fluoroscopic PVIs within a vascular phantom model. The QD magnetic guidewire is biocompatible in its entirety, with excellent resistance to photobleaching and chemical alteration, which is a promising sign for its future clinical implementation.

A flexible silicone tube arrangement structure triboelectric nanogenerator for tennis training monitoring

As the Internet of Things (IoTs) rapidly gain popularity, the demand for self-powered flexible electronic devices is continuously rising, particularly in the intelligent sports field. Hence, we introduced a silicone tube-based triboelectric nanogenerator (ST-TENG) designed for mechanical energy harvesting and tennis training monitoring. The ST-TENG, with its innovative tubular structure, effectively harvests low-frequency mechanical energy and converts it into electrical energy. At a working frequency of 6 Hz, the ST-TENG achieved an open-circuit voltage (Voc) of 122.51 V, a short-circuit current (Isc) of 15.05 µA, and a transfer charge (Qsc) of 33.74 nC. The ST-TENG demonstrates high sensitivity and accuracy in capturing subtle motion details, providing comprehensive data on various aspects of an athlete’s performance. The ST-TENG demonstrated excellent responsiveness to pressure and bending, making it suitable for real-time motion monitoring in tennis. Integrating the ST-TENG into the clothing and equipment of tennis players effectively monitored wrist, waist, and foot movements, providing detailed motion data. This research paves the way for developing highly efficient, self-powered wearable sensors that can significantly enhance the accuracy and sustainability of real-time athletic training monitoring.

An In-Vitro Comparison of Steady State Leakage Rates through Introducer Sheaths Used for Fenestrated Endovascular Aortic Aneurysm Repair

Objectives– fEVAR involves deploying a covered stent into the aorta followed by multiple visceral stents through fenestrations in the main body of graft. The most commonly used large sheaths for cannulation of visceral vessels are the Gore DrySeal Flex, Cook Performer Check-Flo and Medtronic Sentrant. None of these sheaths were designed for the insertion of multiple sheaths, and so a slow but steady leakage of blood occurs during the procedure. The aim of this paper is to assess in an in vitro setting which large bore sheath has the best valve for use when multiple smaller sheaths are inserted through it. MethodsThree large bore introducer sheaths (LBIS) were used for this study, The Gore DrySeal Flex LBIS, Medtronic Sentrant LBIS and Cook Performer Check-Flo LBIS. A test rig was constructed, made of an 18-litre fluid reservoir mounted vertically and receiving a constant supply of water from a domestic water supply which flowed into the reservoir and out of an overflow. The reservoir was connected to the LBIS by a vertical plastic pipe with an internal diameter of 40mm and an isolation valve. The LBIS was connected to the isolation valve by inserting the LBIS up a flexible silicone tube connected to the isolation valve. The LBIS was subject to a constant column/pressure of water and fluid leakage from the LBIS was collected in a plastic pot/tray placed underneath the LBIS. The leakage rates through each LBIS were determined for the following smaller diameter sheath combinations inserted through the valve, one 6 French Sheath, two 6 French Sheaths, two 6 French Sheaths and one 7 French Sheath. This was done to closely mimic a fEVAR procedure in vitro. The procedure was to insert different sheath combinations through the non-return valves in the LBIS and measure the volume of fluid that leaked through the valves. The leaked fluid was weighed, and the weight was converted to volume using the density of water (1g/ml). ResultsThe average (mean) leakage rates for each LBIS and each sheath combination showed that leakage rates when only one sheath was inserted were very low. For all three LBIS’s tested, the leakage rates increased dramatically when multiple sheaths were inserted. The Medtronic LBIS leaked the most, followed by Cook, followed by Gore. For the Cook LBIS, the leakage rates exhibited with 2 x 6 French sheaths were approx. 106 times greater than those for the Gore LBIS and five times greater for the 2 x 6 French + 1 x 7 French sheath combination. A similar comparison for the Medtronic LBIS vs the Gore LBIS yields factors of 132 and 8. ConclusionsLeakage rates increase significantly when multiple sheaths are inserted and the Gore LBIS demonstrates significantly lower leakage than both the Cook and Medtronic during procedures that require simultaneous, multiple insertions of smaller sheaths. Although the Gore Dryseal has by far the lowest leakage rate when three small diameter sheaths are inserted (just under 1ml/s), depending on the duration of the procedure this could still result in significant blood loss.

Modeling of main arteries restenosis in experimental cardiology

Abstract Funding Acknowledgements Type of funding sources: None. Purpose To perform the model of main arteries restenosis and to study the arterial hemodynamics using the original device for modeling of intra-arterial circulation. Materials and methods We used an original device developed by us for modeling of intra-arterial circulation. The main part of the device is a prototype of human arterial vessel - rotameter glass tube 365 mm length, with inlet diameter more than outlet (20 mm vs 16.5 mm). An aqueous solution of glycerin is introduced inside closed system had the same viscosity as the human blood. Flexible silicone tubes are connected with rotameter and electric pump with various modes of work (imitation of pulse waves in regular rhythm (RR), extrasystoles (ES), atrial fibrillation (AF)). We hermetically installed in the rotameter imitation of arterial stent – metal construction with spiral oriented parts 68 mm long. Plastic diaphragms 15 mm long with stenosis of the internal lumen of 50%, 70%, and 90% were alternatively put inside the tube to study intra-arterial hemodynamics. 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure sensor connected to an oscilloscope was injected with a dye - clerical ink. Results When imitating AF after the long pause the speed of fluid flow through the diaphragms increased in comparison with the RR with the pendency: if longer pause was than more speed increased. So, with a stenosis of 50%: the speed with a RR was 2.09 m/s, with AF after the pause <1 s speed was 3.36 m/s, AF after the pause >1, but <2 s speed was 4.97 m/s, AF after the pause >2 s speed was 5.88 m/s; with 70% stenosis: the speed with a RR was 3.24 m/s with AF after the pause <1 s speed was 3.96 m/s, AF after the pause >1, but <2 s speed was 5.87 m/s, AF after the pause >2 s speed was 7.83 m/s; with 90% stenosis, the speed at RR 8.96 m/s, with AF after the pause <1 s speed was 9.46 m/s, AF after the pause >1, but <2 s speed was 11.17 m/s, AF after the pause >2 s speed was 13.45 m/s. The pressure measured by piezoelectrical probe increased proportionally to the speed. We observed the appearance of reflected, standing waves in the edge zones of the diaphragm and stent and a turbulent flow of liquid behind the diaphragm and stent. Conclusion These changes in hemodynamics are characterized by proposed concept of "hydraulic shock". Intense mechanical effect of the pressure waves after the long pauses between cardio cycles in AF in the marginal zones of the diaphragm and intra-arterial stent can cause the further growth, progression of atherosclerosis and restenosis in arterial vessels.

MODELING OF INTRA-ARTERIAL CIRCULATION: APPLICATION IN EXPERIMENTAL CARDIOLOGY

im of our investigation is to evaluate the use of the device for modeling of intra-arterial circulation and substantiate the possibility of its use in experimental cardiology. Materials and methods. The principle part of the model is the cone-shaped narrowed glass cylinder 365 mm long with an inlet diameter of 20 mm, an outlet diameter of 16,5 mm. Two-way fitting with a rubber valve is screwed from the input side. Flexible silicone tubes are attached to both sides of the cylinder, with the other end attached to an electric water pump. The water pump is connected with 12 Volt battery. In one of the outer corners, we insert a needle for introducing dyes (clerical ink) and a silk thread through the fitting valve into the glass tube. We filled the closed circuit with an aqueous solution of glycerin, the viscosity of which was similar to the blood. The water pump provides continuous or intermittent circulation of the glycerin solution in a closed system. We observed the thread movements and turbulent flow colored by the ink during the spread of the pulse waves. Results. We simulated the pulse waves occurring in the regular heart rhythm, as well as arrhythmias. When simulating the extrasystoles, we observed a turbulent fluid flow during the spread of the 1st post-extrasystolic wave behind the installed diaphragm. With the spreading of the 1st post-extrasystolic wave, the pressure level inside the tube is increased in comparison with the regular rhythm. Conclusion. Device for modeling of intra-arterial circulation is simple and reliable in its construction. It imitates the intra-arterial processes in different hemodynamic situations, such as regular heart rhythm, arrhythmias, and atherosclerotic plaques. It can be used in the wide spectrum of experimental works in cardiology, vascular surgery, physiology, pathophysiology, biophysics.

Regular heart rhythm restoration after a period of asystole: modeling in experimental cardiology

Abstract Funding Acknowledgements Type of funding sources: None. Regular heart rhythm restoration after a period of asystole: modeling in experimental cardiology Purpose To study the arterial hemodynamics during the regular heart rhythm restoration after a period of asystole using the original device for modeling of intra-arterial circulation. Materials and methods We used the device for modeling of intra-arterial circulation made by us (Document of invention № RU 202780 U1). The main part of the device is rotameter glass tube - a prototype of human arterial vessel. Electric pump with various modes of work was connected into the closed system with rotameter by flexible silicone tubes. Inside the closed system we introduced an aqueous solution of glycerin diluted to have the same viscosity as the human blood. As indicators for studying the intra-arterial hemodynamics we used intravascular piezoelectric crystal pressure sensor connected to an oscilloscope, 5 mm long silk thread alternately installed inside the tube, and a dye - clerical ink. Results With the electric pump work modes, we were able to imitate the regular heart rhythm (RR) restoration after a period of asystole inside the device for modeling of intra-arterial circulation. We observed the speed of fluid increased in comparison with the RR with the pendency: if longer pause of asystole was than more speed increased. We observed the appearance of reflected, stand waves on the walls of rotameter during the spread of the pulse wave after the long asystole pause. We alternatively put the plastic diaphragm inside the rotameter with internal lumen stenosis of 70% with symmetrical and asymmetrical hole. The speed with a RR was 3.24 m/s, after the pause of asystole 1 s speed was 4.08 m/s, after the pause 2 s speed was 7.36 m/s, after the pause 3 s speed was 9.22 m/s. The pressure measured by piezoelectrical probe increased proportionally to the speed. Conclusion Intense mechanical effect of the pressure waves after the long period of asystole can cause the additional trauma of intima of arterial vessels that can lead to non-stability of atherosclerotic plaques, stimulating of endothelial dysfunction and as a result of atherosclerosis progression with further complications. Changes in hemodynamics we characterized by proposed concept of "hydraulic shock".

Modeling of intra-arterial hemodynamics in main arteries atherosclerosis

Abstract Funding Acknowledgements Type of funding sources: None. Aim. To study intra-arterial hemodynamics of the main arteries in atherosclerosis using the original device for modeling of intra-arterial circulation. Material and methods. To study hemodynamics inside an arterial vessel, we used an original device developed by us for modeling of intra-arterial circulation (Document of invention № RU 202780 U1). The main part of the device is a prototype of an artery - a glass tube of a rotameter with a length of 365 mm, an inlet end with a diameter of 20 mm, an outlet end - 16.5 mm. Flexible silicone tubes are attached to the rotameter on both sides, with free ends connected to an electric pump, with various modes of work (imitation of pulse waves at the regular rhythm (RR), extrasystole (ES), atrial fibrillation (AF)). An aqueous solution of glycerin was introduced into a closed system diluted with water corresponding to the viscosity of the blood. A 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure sensor connected to an oscilloscope was injected with a dye - clerical ink. Plastic diaphragms 15 mm long with stenosis of the internal lumen of 50%, 70%, and 90% were alternately hermetically installed in the rotameter. Results. When imitating ES in the first post-extrasystolic contraction (1PEC), the speed of fluid flow through the diaphragms increased in the 1PEC in comparison with the RR. So, with a stenosis of 50%, the speed with a RR was 2.09 m/s, with an ES 0.03 m/s, with 1PEC 3.83 m/s; with 70% stenosis, the speed at RR 3.24 m/s, with ES 0.04 m/s, with 1PEC 5.26 m/s; with 90% stenosis, the speed at RR 8.96 m / s, with ES 0.10 m/s, with 1PEC 12.36 m/s. The pressure increased proportionally to the speed. We observed the appearance of reflected, standing waves in the edge zones of the diaphragm and a turbulent flow of liquid behind the diaphragm. Conclusion. These changes in hemodynamics are characterized by the concept of "hydraulic shock". Intense mechanical effect of 1PEC pressure waves in the marginal zones of the diaphragm can contribute to the further growth and progression of atherosclerosis in arterial vessels. Abstract Figure.

Do Flexible Silicone Tubes Immersed in Water Combined With Vocalise Improve the Immediate Effect on Voice?

This study aimed to analyze the immediate effect on a singer's voice of a flexible silicone tube immersed in water combined with ascending and descending vocalise scales compared with ascending and descending vocalise scales alone. A pre- and post-intervention quasi-experimental study was conducted. Thirty adult singers between 18 and 45 years old with no laryngeal disorders performed the two techniques for 3 min each on different days. Acoustic measurements of frequency, jitter, shimmer, glottal-to-noise excitation ratio, noise, smoothed cepstral peak prominence (CPPS), maximum phonation time (MPT), voice range profile, and self-perceived vocal effort (Borg Category Ratio 10-BR Scale adapted for vocal effort) were assessed before and after performing the techniques. The results indicated an increase in singers' CPPS and MPT values and a decrease in shimmer and noise when performing with a flexible silicone tube immersed in water combined with vocalise. The singers reported a perception of decreased vocal effort after both methods. However, the diminished perceived vocal effort became more pronounced with the tube phonation technique combined with vocalise. Phonation in tubes combined with vocalise improved the vocal acoustic parameters (including cepstral measurements), increased MPT, and diminished perceived vocal effort. Although using vocalise alone diminished perceived vocal effort, this decrease was more pronounced in the tube phonation technique combined with vocalise.

Device for modeling of intra-arterial circulation: application in experimental cardiology

Abstract Purpose of study Using an original device for modeling of intra-arterial blood circulation, to study the features of intravascular hemodynamics with a regular heart rhythm and with various rhythm disturbances. Material and methods We used an original device developed by us to simulate intra-arterial circulation (Document of invention No. RU 202780 U1). The main part of the device is a glass tube of a rotameter with a length of 365 mm, an inlet end with a diameter of 20 mm, an outlet end of 16.5 mm, which is a model of an arterial vessel. Flexible silicone tubes are attached to the rotameter on both sides, with free ends connected to an electric pump, with various modes of operation (imitation of pulse waves with regular rhythm, premature ventricular contractions (PVCs), atrial fibrillation (AF). An aqueous solution of glycerin was introduced into a closed system diluted with water corresponding to the viscosity of the blood. A 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure probe connected to an oscilloscope. Also it was injected inside the tube a dye - clerical ink. Results With electric pump, we simulated the spreading of the pulse wave in regular heart rate, PVCs and AF. We observed the effect of a pressure wave (deflection of a silk thread, the appearance of a turbulent flow when using a dye) on the walls of the rotameter, with the formation of standing, reflected waves during the PVCs and AF. The pressure probe registered an increase in pressure inside the tube during the spread of the 1st post-extrasystolic contraction wave up to 58%, the wave after a long pause of more than 2 seconds with AF by 44% compared to the regular rhythm. Conclusion A device for modeling of intra-arterial circulation allows a wide range of experimental work in cardiology, normal and pathological physiology, and biophysics. Funding Acknowledgement Type of funding sources: None.

Dynamic Behaviour of Flexible Silicone Tube Subjected to Pulsatile Flow

Flexible Silicone tubes possess superior qualities such as higher corrosion resistance, purity, strength, and inertness compared to other flexible tubes. Hence, these tubes own broad applicability in medical applications as well as other industrial applications. An unsteady flow through the flexible tube can induce severe internal excitation, which results in the flow-induced vibrations. Such vibrations at resonance can cause severe damage to the structure. Concerning the flexible tubes used in sophisticated medical applications, it is imperative to eliminate the structural vibrations, as far as possible. The present study examines the dynamics of the silicone tube under internal excitation due to pulsatile flow. It includes the investigation of the effect of pre-stretch and mean flow velocity on the dynamic behaviour of flexible tube by conducting parametric studies using the operational modal analysis technique. The influence of the mean flow velocity in the flexible tube is a proportional variation in the magnitude of vibration concerning fluid flow rate. An advance in pre-stretch causes a decrease in sagging, and the tube tends to retrieve its original circular cylindrical shape. Owing to this, when the tube is excited due to internal pulsation, the difference between the magnitude of vibration in the horizontal and vertical plane at resonance condition reduces, and the natural frequencies at different planes nearly become equal at higher pre-stretch, where sagging is negligible. The study reveals that for flexible tubes, the tube vibration always stabilizes in an arbitrary plane under excitation due to pulsation. This investigation exhibits that impact hammer excitation is better than constrained external excitation to find the fundamental frequencies of the flexible tube conveying fluid.

Effect of Sagging on Dynamic Characteristics of Silicone Tube Conveying Fluid

Flexible silicone tubes are nowadays broadly employing in medical applications such as drugs or blood-conveying tubes, various infusions as well as medical pumps, and ventilators tubes. Due to better resistance to corrosion and erosion, the subsequent diminishing of wall thickness and change in stiffness of silicone tubes are negligibly small. Hence, these tubes provide trouble-free operations for a prolonged period. Commonly, the fundamental frequency of fluid conveying tubes is influenced by various flow parameters. Recognizing the parameters affecting the fundamental frequency and estimating the extent of the impact of these parameters on the natural frequency are extremely important. This information is vital in the design of precision flow measuring instruments such as Coriolis flowmeter (CFM), which uses vibration techniques for flow measurements. Owing to higher accuracy and the direct fluid flow rate measurements, CFMs are universally accepted in industries for flow measuring applications. When the flexible silicone tube is excited in its sagged condition, there exists a difference in natural frequency in horizontal and vertical planes. Applying pre-stretch decreases the difference in natural frequency, which reduces the sagging and facilitates the tube to regain its cylindrical shape. This paper shows the experimental research on the influence of sagging of the silicone tube conveying fluid, the feasible methods to overcome these effects, and an effective means to capture the deformed shape of a flexible tube. Numerical analysis is carried out in ANSYS using the deformed shape acquired from the laser scanning technique, and the result shows excellent agreement with the experimental values. The damping ratio of the tube is identified by experimenting with varying flow velocities and pre-stretches. This study reveals that it is essential to eliminate the effect of sagging and the subsequent impact of frequency difference in flexible tubes when the principle of Coriolis flowmeter employs for measuring flow rates through flexible tubes.

Thermal performance predictions and tests of a novel type of flat plate solar thermal collectors by integrating with a freeze tolerance solution

A novel design concept of Flat Plate Solar Collectors (FPSCs) is conceived and developed by integrating with a freeze-tolerant (so-called ‘ice immune’) solution using flexible silicone tubing. It is intended to directly run water in the solar thermal systems with the FPSCs instead of using expensive anti-freeze fluids, and to remove secondary heat transfer facilities (e.g. an extra tank with a buried heat exchanger). Successful development of such kind of solar thermal collectors will enable a reduction of installed cost of conventional solar thermal systems without needing secondary heat transfer facilities. In the prophase design, thermal performances of FPSCs with two configurations, i.e. the serpentine tube type and the header riser type, were predicted based on the collector lumped thermal capacitance model alongside CFD (Computational Fluid Dynamics) calculations. Then two prototypes of FPSCs with the ice-immune silicone tubing (one AES serpentine tube type, one modified Chinese micro-heat-pipe-array panel) were made to determine the collector performance and compared to an original AES solar keymark reference panel via experimental tests. The results show that the Chinese micro-heat-pipe-array panel performs better than the AES header riser solar keymark panel in terms of flow rate per m2 collector aperture area, while the AES serpentine tube panel with silicone tubing performs somewhat lower than the solar keymark with Tm∗≤0.035 and better than the solar keymark when Tm∗>0.035. The serpentine tube panel and the Chinese micro-heat-pipe-array panel both integrated with silicone tubing for freeze tolerance are proven to be effective as the modification doesn’t compromise the collector thermal performance markedly.

Analysis of focused indirect ultrasound via high-speed spatially localized pressure sensing and its consequences on nucleation

Ultrasonication is frequently used to promote crystallization and chemical reactions, with many papers reporting the effects of ultrasonic parameters. High-speed pressure inducers (aka pinducers) and signal processing are used here to gain insights into the spatial localization of energy dissipation that occurs during ultrasonication, facilitating a design that allows ultrasonication to be spatially localized inside a tube, without requiring that the probe directly contact the solution. The fluid pressure measured inside of a flexible silicone tube pressed against an ultrasonic probe is observed to move between nearly constant amplitude oscillations to variable shape and amplitude waveforms that deviate significantly from being periodic. Ultrasonic power is transferred to the fluid inside the tube, generating a wide frequency range including via bubble oscillations. Discrete Fourier Transform analysis indicates complex interactions within the experimental system, in addition to the energy transferred inside the tubing at the expected ultrasonic source frequency. The total acoustic intensity decays exponentially with distance from the zone, dropping by more than two orders-of-magnitude for each 1cm increase in distance. The pinducer data analyses guide the design of an experimental setup in which crystals nucleate within fluid inside the zone in the tube, right under the ultrasonic probe.

Intubation Success through I-Gel® and Intubating Laryngeal Mask Airway® Using Flexible Silicone Tubes: A Randomised Noninferiority Trial.

Introduction. The study aims to test whether flexible silicone tubes (FST) improve performance and provide similar intubation success through I-Gel as compared to ILMA. Our trial is registered in CTRI and the registration number is “CTRI/2016/06/006997.” Methods. One hundred and twenty ASA status I-II patients scheduled for elective surgical procedures needing tracheal intubation were randomised to endotracheal intubation using FST through either I-Gel or ILMA. In the ILMA group (n = 60), intubation was attempted through ILMA using FST and, in the I-Gel group (n = 60), FST was inserted through I-Gel airway. Results. Successful intubation was achieved in 36.67% (95% CI 24.48%–48.86%) on first attempt through I-Gel (n = 22/60) compared to 68.33% (95% CI 56.56%–80.1%) in ILMA (n = 41/60) (p = 0.001). The overall intubation success rate was also lower with I-Gel group [58.3% (95% CI 45.82%–70.78%); n = 35] compared to ILMA [90% (95% CI 82.41%–97.59%); n = 54] (p < 0.001). The number of attempts, ease of intubation, and time to intubation were longer with I-Gel compared to ILMA. There were no differences in the other secondary outcomes. Conclusion. The first pass success rate and overall success of FST through an I-Gel airway were inferior to those of ILMA.

First In Vivo Results of a Novel Pediatric Oxygenator with an Integrated Pulsatile Pump.

Extracorporeal membrane oxygenation (ECMO) is a pivotal bridge to recovery for cardiopulmonary failure in children. Besides its life-saving quality, it is often associated with severe system-related complications, such as hemolysis, inflammation, and thromboembolism. Novel oxygenator and pump systems may reduce such ECMO-related complications. The ExMeTrA oxygenator is a newly designed pediatric oxygenator with an integrated pulsatile pump minimizing the priming volume and reducing the surface area of blood contact. The aim of our study was to investigate the feasibility and safety of this new ExMeTrA (expansion mediated transport and accumulation) oxygenator in an animal model. During 6 h of extracorporeal circulation (ECC) in pigs, parameters of the hemostatic system including coagulation, platelets and complement activation, and flow rates were investigated. A nonsignificant trend in C3 consumption, thrombin-antithrombin-III (TAT) complex formation and a slight trend in hemolysis were detected. During the ECC, the blood flow was constantly at 500 ml/min using only flexible silicone tubes inside the oxygenator as pulsatile pump. Our data clearly indicate that the hemostatic markers were only slightly influenced by the ExMeTrA oxygenator. Additionally, the oxygenator showed a constant quality of blood flow. Therefore, this novel pediatric oxygenator shows the potential to be used in pediatric and neonatal support with ECMO.

Amputation of the peritoneal dialysis catheter in the abdominal cavity

An 83-year-old female patient with a 3-year history of peritoneal dialysis (PD) for diabetic nephropathy presented to our clinic with abrupt dialysate drainage failure. The Tenckhoff catheter inserted 3 years ago was a two-cuffed, straight-type flexible silicone tube. Before presentation, she had no abnormal sensation in the abdomen, had not performed any vigorous exercises, or received external force to the abdomen that could have caused catheter damage. No crack or fracture was observed in the PD catheter outside the exit site.

Long-lived spin state of a tripeptide in stretched hydrogel

The longitudinal (T 1), transverse (T 2), and singlet state (T s) relaxation times of the geminal backbone protons (CH2) of L-Leu-Gly-Gly were studied by NMR spectroscopy at 9.4 T in a bovine hide gelatin gel composed in D2O at 25 °C. Gelatin granules were dissolved in a hot solution of the tripeptide and then the solution was allowed to gel inside a flexible silicone tubing. With increases in gelatin content, the T 2 and T s of the CH2 protons correspondingly decreased (T s/T 2 ~ constant), while the change in T 1 was relatively small. The largest observed T s/T 1 value was 3.3 at 46% w/v gelatin that was the lowest gelatin content examined. Stretching the tubing, and hence the gel, brought about anisotropic alignment of the constituents resulting in residual quadrupolar splitting of the resonance from D2O in (2)H NMR spectra, and residual dipolar splitting of the CH2 resonance in (1)H NMR spectra. WALTZ-16 decoupling during the relaxation intervals extended the singlet state relaxation time, but the efficacy diminished as the gels were stretched. Theoretically predicted T 1, T 2, and T s values, assuming intramolecular dipolar coupling as the only source of relaxation, were within the same order of magnitude as the experimentally observed values. Overall we showed that it is possible to observe a long-lived spin state in an anisotropic medium when T 2 is shorter than T 1 in the presence of non-zero residual dipolar couplings.

Oscillatory motion-based miniature magnetic walking robot actuated by a rotating magnetic field

Magnetic micro-robots have been proposed for use in biomedical applications. These studies focus on locomotion control using a gradient, alternating, and rotating magnetic fields at the sub-micro scale. However, this study focuses on a basic mechanism of active locomotion for diagnostic robots. Furthermore, the digestive intestine in the human body has a complex path in which locomotion methods can become either swimming or walking according to the inner condition. Therefore, we propose a new simple mechanism for amphibious locomotion within a rotating magnetic field using the three-axis Helmholtz coil system. The proposed magnetic robot consists of NdFeB permanent spherical magnets, flexible silicone tubes, and legs. Successive changes of actuation of yaw and roll motions cause alternating and walking motions. Direction of movement is decided by rotating the direction of the magnetic field (clockwise or counter-clockwise). In addition, turning directions are decided by the plane of the rotating magnetic field. A magnetic torque between the rotating magnetic field and the magnetic moments produce a constant walking pattern similar to a trotting gait. In addition, an oscillatory motion of the flexible robot body can generate a thrust force in the liquid. Finally, through the various experiments, we evaluate the capability of the locomotion.

Atmospheric-Pressure Plasma Microjet of Argon–Nitrogen Mixtures Directed by Dielectric Flexible Tubes

Herein, a plasma microjet of argon-nitrogen mixtures is produced at atmospheric pressure. The device operation is based on a dielectric-barrier discharge generated by high-voltage positive pulses. We show the possibility to direct the excited species of the jet into flexible silicone tubes and to drastically modify the reactivity at the tube's downstream end by varying the gas composition of the jet. The induced modifications are illustrated by aesthetically pleasing images which unveil the existence of an optimum proportion of nitrogen to argon in order to achieve increased reactivity.

A self-priming, roller-free, miniature, peristaltic pump operable with a single, reciprocating actuator

We present a design for a miniature self-priming peristaltic pump actuated with a single linear actuator, and which can be manufactured using conventional materials and methods. The pump is tolerant of bubbles and particles and can pump liquids, foams, and gases. We explore designs actuated by a motor (in depth) and a shape memory alloy (briefly); and briefly present a manually actuated version. The pump consists of a Delrin acetal plastic body with two integrated valves, a flexible silicone tube, and an actuator. Pumping is achieved as the forward motion of the actuator first closes the upstream valve, and then compresses a section of the tube. The increased internal pressure opens a downstream burst valve to expel the fluid. Reduced pressure in the pump tube allows the downstream valve to close, and removal of actuator force allows the upstream valve and pump tube to open, refilling the pump. The motor actuated design offers a linear dependence of flow rate on voltage in the range of 1.75–3 V. Flow rate decreases from 780 μl/min with increasing back pressure up to the maximum back pressure of 48 kPa. At 3 V and minimum back pressure, the pump consumes 90 mW. The shape memory alloy actuated design offers a 5-fold size and 4-fold weight reduction over the motor design, higher maximum back pressure, and substantial insensitivity of flow rate to back pressure at the cost of lower power efficiency and flow rate. The manually actuated version is simpler and appropriate for applications unconstrained by actuation distance.