scholarly journals Encapsulation of Capacitive Micromachined Ultrasonic Transducers (CMUTs) for the Acoustic Communication between Medical Implants

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 421
Author(s):  
Jorge Oevermann ◽  
Peter Weber ◽  
Steffen H. Tretbar
Keyword(s):  
Data Security ◽  
Ultrasonic Transducers ◽  
Surrounding Tissue ◽  
Center Frequency ◽  
Medical Implants ◽  
Research Groups ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Polyether Ether Ketone ◽  
High Bandwidth ◽  
Ether Ketone

The aim of this work was to extend conventional medical implants by the possibility of communication between them. For reasons of data security and transmitting distances, this communication should be realized using ultrasound, which is generated and detected by capacitive micromachined ultrasonic transducers (CMUTs). These offer the advantage of an inherent high bandwidth and a high integration capability. To protect the surrounding tissue, it has to be encapsulated. In contrast to previous results of other research groups dealing with the encapsulation of CMUTs, the goal here is to integrate the CMUT into the housing of a medical implant. In this work, CMUTs were designed and fabricated for a center frequency of 2 MHz in water and experimentally tested on their characteristics for operation behind layers of Polyether ether ketone (PEEK) and titanium, two typical materials for the housings of medical implants. It could be shown that with silicone as a coupling layer it is possible to operate a CMUT behind the housing of an implant. Although it changes the characteristics of the CMUT, the setup is found to be well suited for communication between two transducers over a distance of at least 8 cm.

Capacitive micromachined ultrasonic transducers: Transmission evaluation with different membrane materials and dimensions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sudhanshu Tripathi ◽  
Rekha Agarwal ◽  
Rashmi Vashisth ◽  
Devraj Singh
Keyword(s):  
Resonant Frequency ◽  
Material Selection ◽  
Transmission Efficiency ◽  
Ultrasonic Transducers ◽  
Transduction Efficiency ◽  
Membrane Material ◽  
Structural Examination ◽  
Membrane Materials ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Output Pressure

Abstract Capacitive micromachined ultrasonic transducers (CMUTs) are dominant in generating and receiving acoustic signals. CMUT transmission efficiency solely depends upon the membrane material utilized. This work presents the structural examination of receiving and transmitting characteristics of CMUT with divergent membrane materials, namely Silicon (Si), Silicon Nitride ( Si 3 N 4 {\mathrm{Si}_{3}}{\text{N}_{4}} ), Indium Phosphide (InP), Zinc Oxide (ZnO), and Polysilicon (Poly-Si). The analysis includes the membrane deflection, pull-in voltage, output pressure, resonant frequency and capacitance modification with variable DC voltage. It has been found that InP gives the pull-in voltage comparable to Si in the receiving mode and have more transduction efficiency in transmitting mode. Effect of dimensions of CMUT on pull-in voltage and resonant frequency are also discussed. The major contribution lies in the analytical and estimation study of CMUT for appropriate membrane material selection meant for transmission and reception in the field of pressure sensing application.

scholarly journals Interfacial Fracture Toughness Comparison of Three Indirect Resin Composites to Dentin and Polyether Ether Ketone Polymer

2020 ◽  
Vol 14 (03) ◽  
pp. 456-461
Author(s):  
Rayhaneh Khalesi ◽  
Mahdi Abbasi ◽  
Zahra Shahidi ◽  
Masoumeh Hasani Tabatabaei ◽  
Zohreh Moradi
Keyword(s):  
Fracture Toughness ◽  
Bond Strength ◽  
Testing Machine ◽  
Composite Resins ◽  
High Wear Resistance ◽  
Luting Cements ◽  
Anterior Teeth ◽  
Polyether Ether Ketone ◽  
Ether Ketone

Abstract Objectives Advances in laboratory composites and their high wear resistance and fracture toughness have resulted in their growing popularity and increasing use for dental restorations. This study sought to assess the fracture toughness of three indirect composites bonded to dental substrate and polyether ether ketone (PEEK) polymer. Materials and Methods This in vitro study was conducted on two groups of dental and polymer substrates. Each substrate was bonded to three indirect composite resins. Sixty blocks (3 × 3 × 12 mm) were made of sound bovine anterior teeth and PEEK polymer. Sixty blocks (3 × 3 × 12 mm) were fabricated of CRIOS (Coltene, Germany), high impact polymer composite (HIPC; Bredent, Germany), and GRADIA (Indirect; GC, Japan) composite resins. Composites were bonded to dentin using Panavia F 2.0 (Kuraray, Japan). For bonding to PEEK, Combo.lign (Bredent) and Visio.Link (Bredent) luting cements were used. In all samples, a single-edge notch was created by a no. 11 surgical blade at the interface. The samples were subjected to 3,500 thermal cycles, and their fracture toughness was measured in a universal testing machine (Zwick/Roell, Germany) by application of four-point flexural load. Statistical Analysis Data were analyzed using one-way analysis of variance, Kruskal–Wallis. Results The fracture toughness of CRIOS–PEEK interface was significantly higher than HIPC–PEEK. The fracture toughness of GRADIA–PEEK was not significantly different from that of HIPC and CRIOS. The fracture toughness of GRADIA–dentin was significantly higher than HIPC–dentin. Conclusion Considering the limitations of this study, GRADIA has the highest bond strength to dentin, while CRIOS shows the highest bond strength to PEEK.

scholarly journals Adhesion Behaviour of Primary Human Osteoblasts and Fibroblasts on Polyether Ether Ketone Compared with Titanium under In Vitro Lipopolysaccharide Incubation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2739 ◽  
Author(s):  
Korbinian Benz ◽  
Andreas Schöbel ◽  
Marisa Dietz ◽  
Peter Maurer ◽  
Jochen Jackowski
Keyword(s):  
Gene Expression ◽  
Protein Level ◽  
Binding Protein ◽  
Sem Images ◽  
Human Osteoblasts ◽  
Polyether Ether Ketone ◽  
Primary Human Osteoblasts ◽  
Titanium Surfaces ◽  
Ether Ketone

The aim of this in vitro pilot study was to analyse the adhesion behaviour of human osteoblasts and fibroblasts on polyether ether ketone (PEEK) when compared with titanium surfaces in an inflammatory environment under lipopolysaccharide (LPS) incubation. Scanning electron microscopy (SEM) images of primary human osteoblasts/fibroblasts on titanium/PEEK samples were created. The gene expression of the LPS-binding protein (LBP) and the LPS receptor (toll-like receptor 4; TLR4) was measured by real-time polymerase chain reaction (PCR). Immunocytochemistry was used to obtain evidence for the distribution of LBP/TLR4 at the protein level of the extra-cellular-matrix-binding protein vinculin and the actin cytoskeleton. SEM images revealed that the osteoblasts and fibroblasts on the PEEK surfaces had adhesion characteristics comparable to those of titanium. The osteoblasts contracted under LPS incubation and a significantly increased LBP gene expression were detected. This was discernible at the protein level on all the materials. Whereas no increase of TLR4 was detected with regard to mRNA concentrations, a considerable increase in the antibody reaction was detected on all the materials. As is the case with titanium, the colonisation of human osteoblasts and fibroblasts on PEEK samples is possible under pro-inflammatory environmental conditions and the cellular inflammation behaviour towards PEEK is lower than that of titanium.

The effects of adding carbon nanotubes to the mechanical and tribological properties of a carbon fibre reinforced polyether ether ketone composite

2009 ◽  
Vol 223 (11) ◽  
pp. 2501-2507 ◽  
Author(s):  
J Li ◽  
L Q Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Wear Resistance ◽  
Carbon Fibre ◽  
Vinyl Ester ◽  
High Wear Resistance ◽  
Compression Moulding ◽  
Mechanical And Tribological Properties ◽  
Polyether Ether Ketone ◽  
Carbon Nano Tubes ◽  
Ether Ketone

The main objective of this article is to develop a high wear resistance carbon fibre (CF)-reinforced polyether ether ketone composite with the addition of multi-wall carbon nano-tubes (MWCNT). These compounds were well mixed in a Haake batch mixer and compounded polymers were fabricated into sheets of known thickness by compression moulding. Samples were tested for wear resistance with respect to different concentrations of fillers. Wear resistance of a composite with 20 wt% of CF increases when MWCNT was introduced. The worn surface features have been examined using a scanning electron microscope (SEM). Photomicrographs of the worn surfaces revealed higher wear resistance with the addition of carbon nanotubes. Also better interfacial adhesion between carbon and vinyl ester in a carbon-reinforced vinyl ester composite was observed.

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