Biomedical Engineering Applications Research Articles

Influence of proteins on the dielectric characteristics of 5CB and 8CB liquid crystals

ABSTRACT In this paper, we study the influence of the protein Bovine Serum Albumin (BSA) on the dielectric properties of liquid crystals (LCs) such as 4-cyano-4-pentyl biphenyl (5CB) and Octyl-4-biphenylcarbonitrile (8CB). Studying the effect of proteins on the dielectric properties of LC is essential for both fundamental research and practical applications in material science, biomedical engineering, biotechnology, and optoelectronic devices. It helps understand the protein behaviour on the surface of LCs, which offers an opportunity to develop novel sensing platforms. A polarising optical microscope (POM) was used to examine the correlation between textures formed by LCs interacting with different concentrations of BSA. In the dielectric studies, dielectric parameters such as impedance (Z), real (Z’) and imaginary (Z’’) parts of the impedance, and the tangential loss (tan δ) were measured. The investigation involved analysing relaxation times using the collected data, revealing distinct behaviours between 5CB and 8CB liquid crystals. Bode and Nyquist’s plots were constructed and analysed to investigate the changes LCs undergo while interacting with BSA. An equivalent electrical circuit (EEC) was constructed using Bode and Nyquist data, from which circuit element values were successfully extracted. The results obtained from the POM studies and the interferences drawn from the EIS can help enhance the performance of protein-based liquid crystal devices.

A novel method for air assisted nanosecond pulsed fiber laser beam transmission micro-channelling on thick PMMA material

The demand for scaling up polymeric materials for mass production or scaling down for microscale applications is at its peak in the modern era. Laser beam technology enables the formation of micro-channels on polymers, specifically polymethyl methacrylate (PMMA). This study examines the viability and cost-effectiveness of employing the diode pump fiber laser transmission technique to create micro-channels on thick, transparent PMMA under air-assisted circumstances for biomedical engineering and micro-fluidics applications. The analysis has included process variables such as pulse frequency, power, and cutting speed, as well as machining parameters including depth of cut, kerf width, and heat-affected zone (HAZ) width. The results of multi-objective optimization indicate that the following parameters—a pulse frequency of 51.30 kHz, a working power of 13 % of 50 W, and a cutting speed of 0.60 mm/s—contribute to the desired microfluidics response values: 12.54 µm depth of cut, 24.05 µm kerf width, and 5.98 µm HAZ width.

Performance analysis of dual material control gate cavity on source electrically doped TFET biosensor for biomedical applications

The fabrication complexity, low sensitivity, detection speed, and costs associated with nanoscale devices have been significant concerns in the development of label-free biosensors. To address these issues, we report a novel dual material control gate cavity on source electrically doped tunnel field-effect transistor (DM-CG-CS-ED-TFET) for label-free biosensors. In this regard, the n+ drain and p+ source regions within the proposed device are induced by applying polarity gate (PG) bias voltages of PG-1 = +1.2 V and PG-2 = −1.2 V, respectively, across the respective polarity gate electrodes. This approach not only overcomes doping control issues but also avoids thermal budget constraints and minimizes fabrication complexity when compared to conventional TFET. For biomolecule sensing in the device, a nanogap cavity is created within the gate dielectric by selectively etching a portion of the polarity gate dielectric layer towards the source side. The performance of the proposed biosensor device is evaluated based on the variations in carrier concentration profile, energy band diagram, electric field, transfer (IDS - VGS) characteristics, drain current (IDS) sensitivity, ON-state current (ION) sensitivity, switching ratio (ION/IOFF) and subthreshold swing (SS) sensitivity. The sensitivity of the device is also investigated based on nano-cavity dimensions, practical challenges such as various filling factors, and the step profile generated from the steric hindrance. Moreover, the effect of temperature on sensitivity has also been investigated. For this, various biomolecules including Streptavidin (k = 2.1), APTES (k = 3.57), ferrocytochrome c (k = 4.7), keratin (k = 8) and Gelatin (k = 12), have been investigated for their performance using Silvaco ATLAS device simulator. The simulation results demonstrate that the proposed biosensor is a viable option for biosensing applications in biomedical engineering.

Development of latex/zinc oxide compounds with antibacterial properties for applications in biomedical engineering

Natural rubber latex (NRL)—a polymer extracted from the rubber tree (Hevea brasiliensis)—has been used in multiple biomedical applications but does not have antibacterial properties. In this work, ZnO nanoparticles with two different morphologies were synthesized and added to NRL at different concentrations in order to evaluate the antibacterial properties of the resulting compounds. The characterization results obtained by electron microscopy and x-ray diffraction showed nanoparticles with spherical (mean size 69 ± 17 nm) and sheet morphology (mean size 154 ± 46 nm) with Wurtzite crystalline phase for both nanomaterials, respectively. The results of antibacterial tests showed that both compounds are effective against E. coli, and the reduction in bacterial viability was 90.3% and 96.4% for sheets and spherical nanomaterials, respectively. In the case of S. aureus, bacterial viability was reduced in both cases. The greatest antibacterial activity was evidenced in the nanoparticles with spherical morphology.

On Inter‐bubble Hydrodynamics and Cluster Formation in Non‐Newtonian Bubbly Columns: A Review

AbstractA comprehensive understanding of the inter‐bubble dynamics and the cluster formations in non‐Newtonian fluids is pivotal for chemical and biomedical engineering applications. In this review, we summarize current research efforts to provide a fundamental understanding and engineering principles of the interactions between bubbles and the dynamics of bubble clusters in non‐Newtonian fluids. Although the majority of research is still predominantly conducted through experimentation, the significance of computational fluid dynamics in elucidating interaction mechanisms has become increasingly prominent in recent years. Moreover, the gas‐liquid systems reviewed in this paper are driven by gravity, which is closer to the actual industrial processes. We indicate the effects of non‐Newtonian fluid special rheological properties (especially viscoelasticity and shear‐dependent viscosity) on the interaction between multiple bubbles and the formation of clusters. We summarize the main empirical correlations in related research, which are useful for the optimization of industry. Ultimately, we address the current trends, limitations, and future directions in this research field.

Cellular uptake of active nonspherical nanoparticles

Due to the potential applications in biomedical engineering, it becomes more and more important to understand the process of engulfment and internalization of nanoparticles (NPs) by cell membranes. Despite the fact that the interaction between cell membranes and passive particles has been widely studied, the interaction between cell membranes and self-propelled nonspherical NPs remains to be elucidated. Here, we present a theoretical model to systematically investigate the influence of the active force, aspect ratio of NPs, particle size, and membrane properties (adhesion energy density and membrane tension) on the cellular uptake of a nonspherical nanoparticle. It is found that the active force generated by an NP can trigger a type of first-order wrapping transition from a small partial wrapping state to a large one. In addition, the phase diagram in the force-aspect ratio (particle size, adhesion energy density, and membrane tension) space displays more complex behaviors compared with that for the passive wrapping mediated merely by adhesion. These results may provide useful guidance to the study of activity-driven cellular entry of active particles into cells.

The use of supramolecular systems in biomedical applications for antimicrobial properties, biocompatibility, and drug delivery.

Supramolecular chemistry is versatile for developing stimuli-responsive, dynamic and multifunctional structures. In the context of biomedical engineering applications, supramolecular assemblies are particularly useful as coatings for they can closely mimic the natural structure and organisation of the extracellular matrix (ECM), they can also fabricate other complex systems like drug delivery systems and bioinks. In the current context of growing medical device-associated complications and the developments in the controlled drug delivery and regenerative medicine fields,supramolecular assemblies are becoming an indispensable part of the biomedical engineering arsenal. This review covers the different supramolecular assemblies in different biomedical applications with a specific focus on antimicrobial coatings, coatings that enhance biocompatibility, surface modifications on implantable medical devices, systems that promote therapeutic efficiency in cancer therapy, and the development in bioinks. The introduced supramolecularsystems include multilayer coating by polyelectrolytes, polymers incorporated with nanoparticles, coating simulation of ECM, and drug delivery systems. A perspective on the application of supramolecular systems is also included.

High-Performance Polyurea Improved by Reactive Nanocluster for Antibiofouling.

Polyurea has found applications in protective coatings. Yet, the too fast polymerization and lack of functions limit its application. Herein, we report a high-performance polyurea via the stepwise polymerization of an isocyanate (NCO)-terminated prepolymer consisting of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (PPG-b-PEG-b-PPG) with a nanocluster synthesized via the hydrolysis of N-phenylaminomethyltriethoxysilane. Such a nanocluster contains low-reactivity secondary amines, so the polymerization of polyurea can be slowed down (over 1 h), which improves its wetting and adhesion to a substrate. The residual silanol groups on the nanocluster further increase the adhesion. Such polyurea exhibits high adhesion on various substrates, including glass, ceramic, steel, copper, titanium, wood, and natural rubber (∼2.35-14.64 MPa). Besides, the nanoclusters can cross-link the prepolymer into a tough network, endowing the polyurea with a high mechanical strength of ∼25 MPa, much higher than the traditional polyaspartic ester polyurea. On the other hand, the PEG segments enable the polyurea to have good fouling resistance against proteins (fibrinogen absorption was reduced by over 90%), bacteria (RBA of S. aureusE. coli and Pseudomonas sp. was less than 10%), as well as diatom (diatom density was less than 100 cells/mm2). The polyurea is expected to find applications in biomedical engineering and marine antifouling.

Thermomechanical evaluation of zinc oxide/hydroxyapatite/high‐density polyethylene hybrid composites

AbstractThis study examines the impact of zinc oxide (ZnO) on the spectral, thermal, mechanical, and morphological characteristics of developed composites of high‐density polyethylene (HDPE). Composite samples were fabricated with different compositions of ZnO (0, 5, 10, 15, and 20 wt%) along with a constant quantity of hydroxyapatite (HA, 10 wt%) in pure HDPE. The synthesized hybrid polymer composites were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), and field emission scanning electron microscopy (FESEM) methods, allowing for a thorough assessment of their spectral, thermal, mechanical, and morphological properties, repectively. FTIR analysis revealed the presence of HA and ZnO metal vibrations in the hybrid polymer samples. The thermal stability was increased by the incorporation of different amounts of ZnO, and the decomposition temperature was increased from 319.31 to 412°C for 10 wt% of ZnO hybrid composites as compared to pure HDPE. DSC findings indicated that increasing the ZnO contents, prompted the degree of crystallinity to rise to 14.81% as contrasted to neat HDPE. It was observed that yield strength and ultimate tensile strength for the 10 wt% ZnO composite increased up to 51.85% and 31.72%, respectively, compared to pure HDPE. However, at higher loading of ZnO, surface cracks were observed, which is detrimental for composite materials. Hence, the improved attributes indicated that the synthesized ZnO/HA/HDPE polymer composites can be a promising material for biomedical engineering applications.

Instantiations of Multiscale Kinship in Pressing‐Defect Distributions in Yttria‐Stabilized Zirconias by Powder Partitioning

Modern dry pressing of ceramic powders using spray‐dried granulates cannot avoid the occurrence of defects related to persisting inter‐ and intra‐granulate interstitial voids. These constitute the parent defect size population limiting the application of polycrystalline ceramics in high‐stress conditions. The mitigation of such defects could widen the range of application in technical and biomedical engineering, reduce the safety range for design, and extend the lifetime of components. Herein, the Weibull size‐effect on strength in size‐partitioned Yttria‐stabilized zirconias (YSZ) feedstocks is used to explore the viability of changing the density distribution of granulate sizes as an effective strategy to obtain a denser particle packing that could reduce the size distribution of strength‐limiting pressing defects. In a direct assessment of critical defect size using multiscale strength testing with a dataset of ≈1300 values, the success of such an approach in increasing the strength reliability for small volume components is demonstrated, along with its ultimate failure in altering the defect size distribution in sintered YSZ ceramics across several length scales. Finally, it is shown that granule morphology (spherical or dimpled) fails to affect the defect density and size distribution in YSZ ceramics.

Mapping flagellated swimmers to surface-slip driven swimmers

Flagellated microswimmers are ubiquitous in natural habitats. Understanding the hydrodynamic behavior of these cells is of paramount interest, owing to their applications in bio-medical engineering and disease spreading. Since the last two decades, computational efforts have been continuously improved to accurately capture the complex hydrodynamic behavior of these model systems. However, modeling the dynamics of such swimmers with fine details is computationally expensive due to the large number of unknowns and the small time-steps required to solve the equations. In this work we propose a method to map fully resolved flagellated microswimmers to coarse, active slip driven swimmers which can be simulated at a reduced computational cost. Using the new method, the slip driven swimmers move with the same velocity, to machine precision, as the flagellated swimmers and generate a similar flow field with a controlled accuracy. The method is validated for swimming patterns near a no-slip boundary, interactions between swimmers and scattering with large obstacles.

Heat transfer enhancement in a trapezoidal cavity due to the cavity orientation and marangoni convection

Understanding Marangoni convection and nanoparticles' convection holds significant potential for applications in materials science, chemical engineering, and biomedical engineering. This article delves into Marangoni convection within cavity flow and its implications for fluid dynamics and thermodynamics. Our study finds out that the various orientations of the trapezoidal cavity affect the convection phenomenon inside the cavity. Additionally, the influence of nanoparticles is explored, with concentrations (0.001≤ φ ≤ 0.01), Rayleigh numbers (104 ≤ Ra ≤106) and Marangoni convection (100 ≤ Ma ≤900). A comparison study considering the Marangoni convection shows that its presence can enhance the heat transfer rate. Considering Marangoni convection with the smaller side at top leads to a notable enhancement of the Nusselt number.

Structure-properties relationships of defined CNF single-networks crosslinked by telechelic PEGs

The high structural anisotropy and colloidal stability of cellulose nanofibrils' enable the creation of self-standing fibrillar hydrogel networks at very low solid contents. Adding methacrylate moieties on the surface of TEMPO oxidized CNFs allows the formation of more robust covalently crosslinked networks by free radical polymerization of acrylic monomers, exploiting the mechanical properties of these networks more efficiently. This technique yields strong and elastic networks but with an undefined network structure. In this work, we use acrylate-capped telechelic polymers derived from the step-growth polymerization of PEG diacrylate and dithiothreitol to crosslink methacrylated TEMPO-oxidized cellulose nanofibrils (MATO CNF). This combination resulted in flexible and strong hydrogels, as observed through rheological studies, compression and tensile loading. The structure and mechanical properties of these hydrogel networks were found to depend on the dimensions of the CNFs and polymer crosslinkers. The structure of the networks and the role of individual components were evaluated with SAXS (Small-Angle X-ray Scattering) and photo-rheology. A thorough understanding of hybrid CNF/polymer networks and how to best exploit the capacity of these networks enable further advancement of cellulose-based materials for applications in packaging, soft robotics, and biomedical engineering.

Electro-fluid-dynamics (EFD) of soft-bodied organisms swimming through mucus having dilatant, viscous, and pseudo-plastic properties

The sperm propelling mechanism has been proposed as a possible resource for soft micro-robots in confined spaces, with potential applications in biomedical engineering. Human sperm cells essentially swim through the non-Newtonian liquid (cervical mucus) to reach their target. Thus, sperm cells swimming through non-Newtonian fluids is not vital only for physiology, but also for the fabrication of swimming micro-robots. Inspired by these remarkable applications, we examine the basic mechanics of spermatozoa motility using an undulating sheet model. This undulating sheet is bounded between two rigid walls which is self-propeling in the negative axial direction. The liquid around the spermatozoa is taken as Carreau fluid with electro-osmotic properties. The application of the lubrication approximation results in the reduction of momentum equations. The resulting ODE is solved numerically via the finite difference method and MATLAB’s built-in routine bvp5c. The unknowns that are present in the boundary conditions are refined by the root-finding algorithm. Power losses, cell speed, flow rate, velocity of the fluid, and streamline pattern are visualized by graphs. The findings of this study have important implications for the designing and optimization of electrically controlled microswimmers.

ROLE OF INORGANIC PARTICLES FOR THE FORMULATION OF NANOPARTICLES: A REVIEW

Inorganic particles do not have carbon in their backbone and are produced through various geochemical processes, i.e. they are not biological in nature. It is a common practice to use inorganic particles to formulate nanoparticles as their size is near nanoscale dimensions. Various inorganic particles such as silver, gold, silica, alumina and magnetite have been used to fabricate nanoparticles. These nanoparticles are used in different fields, such as magnetic recording, chemical sensing, anti-microbial assays and enzyme immobilization. They have several advantages due to their increased surface area-to-volume ratio, enhancing their reactivity. This review will discuss various inorganic particles used for nanoparticle preparation and their structure, properties, and applications in biomedical engineering. The major applications of formulated nanoparticles are used in biomedicines for drug delivery. They can deliver the drug to the specific site by crossing many biophysical, biochemical and biological barriers.

Shape Memory Hydrogels for Biomedical Applications.

The ability of shape memory polymers to change shape upon external stimulation makes them exceedingly useful in various areas, from biomedical engineering to soft robotics. Especially, shape memory hydrogels (SMHs) are well-suited for biomedical applications due to their inherent biocompatibility, excellent shape morphing performance, tunable physiochemical properties, and responsiveness to a wide range of stimuli (e.g., thermal, chemical, electrical, light). This review provides an overview of the unique features of smart SMHs from their fundamental working mechanisms to types of SMHs classified on the basis of applied stimuli and highlights notable clinical applications. Moreover, the potential of SMHs for surgical, biomedical, and tissue engineering applications is discussed. Finally, this review summarizes the current challenges in synthesizing and fabricating reconfigurable hydrogel-based interfaces and outlines future directions for their potential in personalized medicine and clinical applications.

A comprehensive review of blood component detection utilizing One-Dimensional, Two-Dimensional, and photonic crystal fiber biosensors

This comprehensive review investigates the diverse landscape of blood component detection through the one-dimensional, two-dimensional, and photonic crystal fiber biosensors. Each biosensor, dedicated to specific blood components, is scrutinized in detail, with a focus on key parameters such as Quality Factor (Q) coefficient Loss, Figure of Merit (FOM), and Detection Limit (DL). The study discerns notable advancements in sensitivity and confinement loss within the realm of photonic crystal fiber sensors, attributing these improvements to recent structural modifications. The findings contribute valuable insights into the state-of-the-art techniques employed in blood component detection, paving the way for enhanced biosensor technologies in biomedical applications.

Evolution of 3d printing technology in fabrication of microfluidic devices and biological applications: a comprehensive review

Lab-on-a-chip or LOC is a term that is used to describe microfluidic devices that integrate multiple analyte detection, which are normally carried out in a laboratory, into one micro-chip unit and may have applications in diverse fields such as electronics, medicine and biomedical domains. Even though microfluidics has advanced greatly during the past decade due to increased needs for portability, reduced sample requirement and multiple analyte detection capabilities biological research has not adopted the technology at the required pace. This may be owing to the time-consuming and expensive process involved in the microfabrication of biochips, the requirement of specialised setup facilities and the extremely high cost associated with microfluidics as compared to conventional technologies. In recent years, three-dimensional (3D) printing has piqued curiosity in the scientific community. It has the potential to create complex, high-resolution structures and that too in a short timeframe depending upon device complexity. This could inspire progressive research in microfluidics, particularly finding applications in biomedical engineering and point-of-care diagnostics. This article gives an overview of how 3D printing aids in the manufacture of microfluidic devices for biological applications, as well as the existing 3D printing methods which are utilised for fabrication and the future perspective in the development of microfluidic devices.

Comparative Study on the Lubrication Mechanism and Performance of Two Representative Ionic and Nonionic Self-Adhesive Polymer Coatings.

Surface modification of lubricating coatings on biomedical devices is a pivotal strategy to improve the overall performance and clinical efficacy, significantly reducing friction between devices and human tissues and mitigating tissue damage during intervention and long-term implantation. Recently, various hydrophilic polymeric materials have been used for achieving surface functionalization, endowing the biomedical device with excellent superlubrication performance. N-Vinylpyrrolidone (NVP) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are two typical representatives of nonionic and zwitterionic materials. However, there is still a research gap in a comparative study of the lubrication mechanisms and properties between them. In this study, a bioinspired and dopamine-assisted codeposition technique was used to fabricate biomimetic hydrophilic coatings, including P(DMA-NVP) and P(DMA-MPC), on polyurethane. To achieve a thorough comparative analysis of the self-adhesive coating performance, 3 M ratios of the copolymers were synthesized and comprehensive material evaluations were conducted. Additionally, surface morphology, hydrophilicity, and lubrication at both the microscale and macroscale were performed. It was found that both hydrophilic coatings exhibited good stability. The P(DMA-MPC) coating, due to the ability to attract and bind a large number of water molecules, demonstrated superior lubrication effects compared to the P(DMA-NVP) coating. The study provides an in-depth understanding of the lubrication behavior of the self-adhesive coatings to enhance the functionality and application in biomedical engineering.

Three-Dimensional Printing Strategies for Enhanced Hydrogel Applications.

This study explores the dynamic field of 3D-printed hydrogels, emphasizing advancements and challenges in customization, fabrication, and functionalization for applications in biomedical engineering, soft robotics, and tissue engineering. It delves into the significance of tailored biomedical scaffolds for tissue regeneration, the enhancement in bioinks for realistic tissue replication, and the development of bioinspired actuators. Additionally, this paper addresses fabrication issues in soft robotics, aiming to mimic biological structures through high-resolution, multimaterial printing. In tissue engineering, it highlights efforts to create environments conducive to cell migration and functional tissue development. This research also extends to drug delivery systems, focusing on controlled release and biocompatibility, and examines the integration of hydrogels with electronic components for bioelectronic applications. The interdisciplinary nature of these efforts highlights a commitment to overcoming material limitations and optimizing fabrication techniques to realize the full potential of 3D-printed hydrogels in improving health and well-being.