The long-term reliability of pre-charged CMUTs for the powering of deep implanted devices

2021 ◽  
Author(s):  
Marta Saccher ◽  
Shinnosuke Kawasaki ◽  
Ronald Dekker
Keyword(s):  
Implanted Devices

Adhesion and Electrical Insulation of Thin Polymeric Coatings Under Saline Exposure

1987 ◽  
Vol 110 ◽  
Author(s):  
R. N. Leyden ◽  
D. I. Basiulis
Keyword(s):  
Barrier Properties ◽  
Peel Strength ◽  
Polymer Coatings ◽  
Polymeric Coatings ◽  
Adhesive Failure ◽  
Short Term ◽  
Leakage Currents ◽  
Electrical Bias ◽  
Implanted Devices

AbstractA study was made of the adhesion of insulating polymer coatings under long term exposure to electrical bias. Since a common mode of failure in implanted devices is the penetration of water into poorly adhering insulation/conductor interfaces followed by electrolytic degradation, development of processes, primers, and insulators with good adhesion that resist the effects of water were sought. Polyimide coatings were tested for their ion barrier properties by immersion of insulated comb patterns in saline with 9 V D.C. bias between the comb fingers. Leakage currents, measured over three years exposure, increased from several picoamps initially to several nanoamps in surviving specimens. Subsequent studies showed that dramatic improvements in the moisture durability of the adhesion could be obtained using Hitachi's aluminum chelate type primer. Whereas the peel strength of polyimide on unprimed platinum fell more than 90% after several hours of boiling saline exposure, the peel strength of polyimide coatings on primed surfaces remained at over 80% of their initial values. ESCA analysis of the peel interfaces showed that both aluminum oxide and polyimide remain on the substrate after peeling back the polyimide. This suggests a combination of cohesive and adhesive failure at the primer/polyimide interface. The effects of exposure of the polymer/substrate interfaces (edges) to saline and electrochemical stress were examined by patterning circular openings in the polyimide. A 10 V anodic potential was found to damage adhesion to titanium as far as 75 microns away from the edge. Pulsing at 500 Hz, 1 V peak to peak was found to have no measurable effect in the short term.

scholarly journals Suprachoroidal MIGS Devices

2020 ◽  
pp. 105-119
Author(s):  
Julian Garcia-Feijoo ◽  
Jose Maria Martinez-de-la-Casa ◽  
Lucia Perucho
Keyword(s):  
Glaucoma Surgery ◽  
Cell Loss ◽  
Term Efficacy ◽  
Suprachoroidal Space ◽  
Early Results ◽  
Outflow Pathway ◽  
Implanted Devices ◽  
Ab Interno

Abstract The suprachoroidal outflow pathway has the potential to reduce intraocular pressure (IOP) significantly but has been associated with sight-threatening complications including severe and prolonged hypotony. Historically, suprachoroidal devices have been implanted ab externo requiring a conjunctival peritomy and scleral flap dissection. Additionally, the long-term efficacy of previous attempts to harness this space has been disappointing due to occlusion of implanted devices by fibrosis in the suprachoroidal space. More recently, there have been a number of suprachoroidal devices that are injected ab interno., including the CyPass Micro-Stent (Alcon Laboratories Inc., Fortworth, Texas, USA), the iStent Supra (Glaukos Corporation, San Clemente, CA, USA) and the MINIject (iSTAR Medical Isnes, Belgium). These have utilized a clear corneal entry, thereby sparing the conjunctiva. Early results with these ab-interno devices showed safety and efficacy in IOP-lowering that is similar to Schlemm’s canal minimally invasive glaucoma surgery devices and procedures. Despite the ab-interno approach, their long-term efficacy also seems to be limited by fibrosis. In addition, the first commercially available ab-interno suprachoroidal device, the CyPass Micro-Stent, has been voluntarily withdrawn globally by the manufacturer in August 2018, after 5-year follow-up data demonstrated a higher level of endothelial cell loss with the device than in controls. The iStent Supra and MINIject are not yet available commercially.

Healing Response of Normal Canine Aorta and Iliac Artery to a Nitinol Stent Encapsulated in Carbon-Lined ePTFE

2001 ◽  
Vol 8 (3) ◽  
pp. 274-281 ◽  
Author(s):  
Jonathan D. Woody ◽  
Gary Nishanian ◽  
George E. Kopchok ◽  
Nam I.I. Kim ◽  
Carlos E. Donayre ◽  
...  
Keyword(s):  
Stent Graft ◽  
Iliac Artery ◽  
Endothelial Lining ◽  
Nitinol Stent ◽  
Healing Response ◽  
Novel Approach ◽  
Group 2 ◽  
Graft Migration ◽  
Implanted Devices

Purpose: To evaluate the healing response of normal canine arteries to a self-expanding nitinol stent encapsulated in carbon-lined expanded polytetrafluoroethylene (ePTFE). Methods: Twenty-eight dogs were divided into aortic (n = 18) or iliac (n = 10) groups. In the latter, 2 animals were assigned to implantation intervals of 7, 30, and 90 days, respectively; 4 were designated for 180-day implantation. Half of the animals in each subgroup received a second overlapping stent-graft in one iliac artery. In the aortic cohort, 6 animals were assigned to the 180-day implantation group (2 with dual devices) and 3 to each of the others (1 dual implantation in each group). The devices were evaluated with angiography and intravascular ultrasound at implantation and explantation. After harvesting and gross examination, the specimens were examined microscopically and with scanning electron microscopy. Results: The 49 implanted devices (24 aortic and 25 common iliac) were all widely patent at explantation, save for 2 iliac stents that had moderate (<40%) stenosis. No neointima was present at the 7-day interval. All stents were covered by thin neointima (<150 µm) at 30 days. At 180 days, an endothelial lining was present in the proximal and distal segments of all stents; in 4 of the 6 aortic stents, this endothelial lining was complete, whereas none of the iliac devices had endothelium in the midsegment at 180 days. At 1 year, 2 of the aortic specimens had an incomplete endothelial lining, whereas the lining was complete in the third. There was no evidence of stent-graft migration or inflammation associated with any device. Conclusions: The carbon-lined ePTFE-encapsulated stent is a novel approach to arterial stenting. The progressive endothelialization and lack of inflammatory reaction may provide improved long-term patency. Further study of this stent-graft design is warranted.

Electrokinetic Transport of Molecules Through Nanochanneled Membranes

2010 ◽  
Author(s):  
Alessandro Grattoni ◽  
Xuewu Liu ◽  
Zongxing Wang ◽  
Jaskaran Gill ◽  
Arturas Ziemys ◽  
...  
Keyword(s):  
Drug Release ◽  
Biological Molecules ◽  
Operational Control ◽  
Drug Molecules ◽  
Passive Release ◽  
Treatment Of Diabetes ◽  
Active Release ◽  
Implanted Devices

Our research group was the first one to microfabricate and demonstrate nano-channels in silicon membranes (1, 2). We employed nano-channeled chips to provide immuno-isolation for cell transplantation towards the treatment of diabetes (3), for biomolecular separation (4), and for the controlled passive and active release of drug molecules from implanted capsules (5). We showed that the constraints placed upon molecular agitation in nano-channels affected their concentration-driven transport kinetics (6, 7). A zero-order passive release of biological molecules was achieved, by the rational tailoring of nano-channels dimensions. This achievement allowed releasing of a constant amount of drugs over a long period of time. However, the development and optimization of many drug therapies require long-term drug delivery with controlled but variable dosage using miniaturized systems (8). Moreover, application such as drug release from implanted devices requires tight operational control, of regulatory agency caliber. We have engaged in the development and characterization of elecroosmotic nano-channels membranes, and present our results in this communication. These include the influence of the drug release rate on nanochannel size, membrane configuration, and applied voltage.

scholarly journals Imaging of patients with implanted devices and arrhythmia

2016 ◽  
Vol 20 (2) ◽  
Author(s):  
Nam Ju Lee ◽  
Harold I. Litt
Keyword(s):  
Ventricular Arrhythmias ◽  
Standard Technique ◽  
Inversion Pulse ◽  
Gadolinium Enhancement ◽  
Cardiac Devices ◽  
Vt Ablation ◽  
Lge Cmr ◽  
Implanted Devices

Expanding implantable cardioverter-defibrillator (ICD) indications and significant morbidity and mortality reduction benefits have resulted in a large number of routine ICD implants with appropriate ICD shocks for ventricular arrhythmias. The side-effects and lack of long-term efficacy of antiarrhythmics have made ventricular tachycardia (VT) ablation an increasingly attractive treatment option. Although cardiac magnetic resonance imaging (CMR) is considered the gold standard technique for imaging of myocardial fibrosis to diagnose and guide VT ablation targets in patients with cardiac arrhythmia, safety concerns and significant artifacts from the devices significantly limit the application of CMR. We discuss how to decrease artifact from cardiac devices and the role of a modified inversion pulse late gadolinium enhancement (LGE) CMR sequence as a useful tool in this setting, and we review techniques, safety protocols and limitations from the perspective of our institution’s experience.

scholarly journals Implanted Flexible Electronics: Set Device Lifetime with Smart Nanomaterials

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 157
Author(s):  
Hoang-Phuong Phan
Keyword(s):  
Flexible Electronics ◽  
High Performance ◽  
Industrial Applications ◽  
Future Research ◽  
Research Directions ◽  
Future Research Directions ◽  
Device Lifetime ◽  
The Internet Of Things ◽  
Implanted Devices

Flexible electronics is one of the most attractive and anticipated markets in the internet-of-things era, covering a broad range of practical and industrial applications from displays and energy harvesting to health care devices. The mechanical flexibility, combined with high performance electronics, and integrated on a soft substrate offer unprecedented functionality for biomedical applications. This paper presents a brief snapshot on the materials of choice for niche flexible bio-implanted devices that address the requirements for both biodegradable and long-term operational streams. The paper also discusses potential future research directions in this rapidly growing field.

scholarly journals Impact of pregnancy and risk factors for ventricular arrhythmias in women with tetralogy of Fallot

Open Heart ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. e001400
Author(s):  
Alessia Quattrone ◽  
Oyvind H Lie ◽  
Eirik Nestaas ◽  
Charlotte de Lange ◽  
Kirsti Try ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Tetralogy Of Fallot ◽  
Survival Rates ◽  
Holter Monitoring ◽  
National Database ◽  
High Survival ◽  
Mechanical Dispersion ◽  
Patients Experience ◽  
Implanted Devices

ObjectivePatients with tetralogy of Fallot (TOF) have high survival rates 30 years after surgical repair. Many patients experience pregnancy; however, the effects of pregnancy on the long-term cardiovascular outcome are not well known. We investigated the association of pregnancy and cardiac function with occurrence of ventricular arrhythmia (VA) in women with TOF.MethodsWe recruited 80 women with repaired TOF from the national database. Holter monitoring or implanted devices detected VA, defined as non-sustained or sustained ventricular tachycardia or aborted cardiac arrest. All patients underwent echocardiography. Blood tests included NT-proBNP (N-terminal pro-brain natriuretic peptide).Results55 (69%) women had experienced pregnancy. Mean age was lower in nulliparous compared with those with children (30±9 vs 40±9, p<0.01).VA had occurred in 17 (21%) women. Prevalence of VA was higher in women who had experienced pregnancy (n=16, 94%) compared with nulliparous (n=1, 6%) (p=0.02), also when adjusted for age (OR 12.9 (95% CI 1.5 to 113.2), p=0.02).Right ventricular mechanical dispersion was more pronounced in patients with VA (50±8 ms vs 39±14 ms, p=0.01, age-adjusted OR 2.1 (95% CI 1.3 to 7.5), p=0.01). NT-proBNP was also a marker of VA (211 ng/L (127 to 836) vs 139 ng/L (30 to 465), p=0.007). NT-proBNP >321 ng/L (normal values <170 ng/L) detected women with VA (p=0.019), also independent of age (OR 7.2 (95% CI 1.7 to 30.1), p=0.007).ConclusionPregnancy was associated with higher prevalence of VA among women with TOF. Right ventricular mechanical dispersion and NT-proBNP were age-independent markers of VA. These may have importance for pregnancy counselling and risk stratification.

scholarly journals Antibacterial Coatings for Improving the Performance of Biomaterials

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 139 ◽  
Author(s):  
Jon Andrade-Del Olmo ◽  
Leire Ruiz-Rubio ◽  
Leyre Pérez-Alvarez ◽  
Virginia Sáez-Martínez ◽  
José Luis Vilas-Vilela
Keyword(s):  
Health Care ◽  
Biofilm Formation ◽  
Bacterial Contamination ◽  
Complete Removal ◽  
Biomedical Devices ◽  
Long Term Stability ◽  
Antibacterial Coatings ◽  
Enormous Number ◽  
Implanted Devices

Biomedical devices have become essential in the health care. Every day, an enormous number of these devices are used or implanted in humans. In this context, the bacterial contamination that could be developed in implanted devices is critical since it is estimated that infections kill more people than other medical causes. Commonly, these infections are treated with antibiotics, but the biofilm formation on implant surfaces could significantly reduce the effectiveness of these antibiotics since bacteria inside the biofilm is protected from the drug. In some cases, a complete removal of the implant is necessary in order to overcome the infection. In this context, antibacterial coatings are considered an excellent strategy to avoid biofilm formation and, therefore, mitigate the derived complications. In this review, the main biomaterials used in biomedical devices, the mechanism of biofilm formation, and the main strategies for the development of antibacterial coatings, are reviewed. Finally, the main polymer-based strategies to develop antibacterial coatings are summarized, with the aim of these coatings being to avoid the bacteria proliferation by controlling the antibacterial mechanisms involved and enhancing long-term stability.

scholarly journals Comparison of catheter-related infection risk in two different long-term venous devices in adult hematology-oncology patients

2004 ◽  
Vol 59 (5) ◽  
pp. 291-295 ◽  
Author(s):  
Luís Fernando Pracchia ◽  
Lúcia Cristina Santos Dias ◽  
Pedro Enrique Dorlhiac-Llacer ◽  
Dalton de Alencar Fisher Chamone
Keyword(s):  
Demographic Data ◽  
Infection Risk ◽  
Survival Ratio ◽  
Central Venous ◽  
Free Survival ◽  
Catheter Related Infection ◽  
Infection Incidence ◽  
Implanted Devices

PURPOSE: Infection is the leading complication of long-term central venous catheters, and its incidence may vary according to catheter type. The objective of this study was to compare the frequency and probability of infection between two types of long-term intravenous devices. METHODS: Retrospective study in 96 onco-hematology patients with partially implanted catheters (n = 55) or completely implanted ones (n = 42). Demographic data and catheter care were similar in both groups. Infection incidence and infection-free survival were used for the comparison of the two devices. RESULTS: In a median follow-up time of 210 days, the catheter-related infection incidence was 0.2102/100 catheter-days for the partially implanted devices and 0.0045/100 catheter-days for the completely implanted devices; the infection incidence rate was 46.7 (CI 95% = 6.2 to 348.8). The 1-year first infection-free survival ratio was 45% versus 97%, and the 1-year removal due to infection-free survival ratio was 42% versus 97% for partially and totally implanted catheters, respectively (P <.001 for both comparisons). CONCLUSION: In the present study, the infection risk was lower in completely implanted devices than in partially implanted ones.

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