76 research outputs found
Development of Robust Biofunctional Interfaces for Applications in Selfcleaning Surfaces, Lab-Ona-Chip Systems, and Diagnostics
No full textBiofunctional interfaces capable of anchoring biomolecules and nanoparticles of interest onto a platform are the key components of many biomedical assays, clinical pathologies, as well as antibacterial and antiviral surfaces. In an ideal biofunctional surface, bio-entities and particles are covalently immobilized on a substrate in order to provide robustness and long-term stability. Nonetheless, most of the reported covalent immobilization strategies incorporate complex wet-chemical steps and long incubation times hindering their implementation for mass production and commercialization. Another essential factor in the biointerface preparation, specially with regard to biosensors and diagnostic applications, is utilization of an efficient and durable blocking agent that can inhibit non-specific adsorption of biomolecules thereby enhancing the sensitivity of sensors by diminishing the level of background noise. Many of the commonly used blocking agents lack proper prevention of non-specific adsorption in complex fluids. In addition, most of these agents are physically attached to surfaces making them unreliable for long-term usage in harsh environments (i.e. where shear stresses above 50 dyn/cm2 or strong washing buffers are involved).
This thesis presents novel and versatile strategies to covalently immobilize nanoparticles and biomolecules on substrates. The new surface coating techniques are first implemented for robust attachment of TiO2 nanoparticles onto ceramic tiles providing self-cleaning properties. Further, we utilize similar strategies to covalently immobilize proteins and culture cells in microfluidic channels either as a full surface coating or as micropatterns of interest. The new strategies allow us to obtain adhesion of ~ 400 cells/mm2 in microfluidic channels after only 1-day incubation, which is not achievable by the conventional methods. Moreover, we show the possibility of covalently micropatterning of biomolecules on lubricant-infused surfaces (LISs) so as to attain a new class of biofunctional LISs. By integration of these surfaces into a biosensing platform, we are able to detect interleukin 6 (IL-6) in a complex biofluid of human whole plasma with a limit of detection (LOD) of 0.5 pg.mL-1. This LOD is significantly lower than the smallest reported IL-6 LOD in plasma, 23 pg mL-1, using a complex electrochemical system. The higher sensitivity of our developed biosensor can be attributed to the distinguish capability of biofunctional LISs in preventing non-specific adhesion of biomolecules compared to other blocking agents.ThesisDoctor of Philosophy (PhD)The key goal of this thesis is to provide new strategies for preparation of robust and durable biointerfaces that could be employed for many biomedical devices such as self-cleaning coatings, microfluidics, point-of-care diagnostics, biomedical assays, and biosensors in order to enhance their efficiency, sensitivity, and precision. The introduced surface biofunctionalization methods are straightforward to use and do not require multiple wet-chemistry steps and incubation times, making them suitable for mass production and high throughput demands. Moreover, the introduced surface coating strategies allow for creation of antibody/protein micro-patterns covalently bound onto a biomolecule-repellent surface. The repellent property of the surfaces is resulted from infusion of an FDA-approved lubricant into the surface of a chemically modified substrate. While the surface repellency can effectively prevent non-specific adhesion of biomolecules, the patterned antibodies can locally capture the desired analyte, making them a great candidate for biosensing
A comparative study of occupant thermal modeling
No full textIn North America, the ventilation system in indoor environments have been almost exclusively associated with the use of conventional ceiling air distribution systems, where the air is moved via ducts through ceiling diffusers. However, in the past years there has been a growing interest in the application of localized ventilation systems for which numerous studies have been conducted looking at different aspects such as enhanced thermal comfort, improved indoor air quality and lower energy consumption. It has also been determined that a typical localized ventilation system creates a non-uniform thermal environment, which might cause thermal discomfort due to excessive vertical temperature difference, draft, and asymmetric thermal conditions. As an alternative to the experimental measurments, the Computational Fluid Dynamics (CFD) methods have been used to predict the airflow field around the occupant. The correct prediction of the flow field is dependent upon the proper modeling of the occupant body since the actual shape of human body is complicated and its heat distribution is known to be non-uniform. However, past CFD studies on the subject were mainly performed by modeling the occupant as a block with uniform heat distribution, in order to simplify the problem and decrease the computational cost. In the present study, commercially available CFD software, Airpak from Fluent Inc., is used to simulate the occupant body by using a variety of modeling techniques in order to quantify the impact of occupant modeling assumptions on the bouyancy and inertia in induced flow field
Strong Scalability Studies for the 2-D Poisson Equation on the Taki 2021 Cluster with Historical Comparison
No full textThe new 2021 nodes in the cluster taki in the UMBC High Performance Computing Facility contain two 24core Intel Cascade Lake CPUs and 192 GB of memory per node, connected by an high-performance InfiniBand interconnect. Parallel performance studies for the memory-bound test problem of the Poisson equation in two spatial dimensions yield several conclusions: Strong scalability studies demonstrate excellent performance when using multiple nodes due to the low latency of the high-performance interconnect and good speedup when using all cores of the multi-core CPUs. For the largest numbers of processes per node, the runtime for the code is not significantly reduced, a typical behavior characteristic of memory-bound code. Comparisons to results on past clusters in HPCF bring out that core-per-core performance of serial code improvements has improved again, demonstrating the quality of the newest CPUs. Also node-per-node performance of parallel code continues to improve due to the larger number of cores available on a node. albeit we have fewer nodes in taki 2021 than we had in previous partitions.The hardware used in the computational studies is part of the UMBC High Performance Computing Facility (HPCF). The facility is supported by the U.S. National Science Foundation through the MRI program (grant nos. CNS–0821258, CNS–1228778, OAC–1726023, and CNS–1920079) and the SCREMS program (grant no. DMS–0821311), with additional substantial support from the University of Maryland, Baltimore County (UMBC). See hpcf.umbc.edu for more information on HPCF and the projects using its resources. Co-author Ehsan Shakeri was supported by UMBC as HPCF RA.https://userpages.umbc.edu/~gobbert/papers/PoissonHPCF20241.pd
Whole slide imaging systems for digital pathology
No full textDigital pathology is based on the use of digital images of tissues for diagnosis of diseases. In the emerging clinical practice of digital pathology, images of tissue slides are acquired with a high-resolution and high-throughput automated microscope, a so called Whole Slide Imaging (WSI) system. We designed, built and characterized a modular WSI platform for conducting two- and three-dimensional brightfield microscopy, the most common modality in this field
Underwater ultra-wideband fingerprinting-based localization
No full textIn this work a new location fingerprinting-based localization algorithm is proposed for an underwater medium by utilizing ultra-wideband (UWB) signals. In many conventional underwater systems, localization is accomplished by utilizing acoustic waves. On the other hand, electromagnetic waves haven't been employed for underwater localization due to the high attenuation of the signal in water. However, it is possible to use UWB signals for short-range underwater localization. In this work, the feasibility of performing localization for an underwater medium is illustrated by utilizing a location-based fingerprinting approach. Existing algorithms for an indoor environment are evaluated in this project for an underwater medium. These algorithms are based on a neural networks or maximum likelihood estimator. Further, we also consider a classical k-nearest neighbors (KNN) approach. In addition, by employing the concept of compressive sampling, we propose a sparsity-based localization approach for which we define a system model exploiting the spatial sparsity. Moreover, a recently proposed grid mismatching algorithm is also adapted to the current localization framework and its performance is evaluated. Finally, the performance of the proposed methods is compared with the existing fingerprinting-based localization approaches.Electrical EngineeringCircuits and SystemsElectrical Engineering, Mathematics and Computer Scienc
The Fabrication and Bonding of Thermoplastic Microfluidics: A Review
No full textVarious fields within biomedical engineering have been afforded rapid scientific advancement through the incorporation of microfluidics. As literature surrounding biological systems become more comprehensive and many microfluidic platforms show potential for commercialization, the development of representative fluidic systems has become more intricate. This has brought increased scrutiny of the material properties of microfluidic substrates. Thermoplastics have been highlighted as a promising material, given their material adaptability and commercial compatibility. This review provides a comprehensive discussion surrounding recent developments pertaining to thermoplastic microfluidic device fabrication. Existing and emerging approaches related to both microchannel fabrication and device assembly are highlighted, with consideration toward how specific approaches induce physical and/or chemical properties that are optimally suited for relevant real-world applications
Impact of occupant modelling on the prediction of airflow around occupants in a ventilated room
No full textLocalized ventilation systems typically create highly asymmetric or non-isothermal environments around occupants with significant vertical temperature gradient and highly non-uniform airflow regimes that could be directed toward a segment of the body. These effects may have pronounced impact on occupant's thermal comfort. The airflow field and temperature distribution near the occupant can be determined either by performing full-scale measurements or by simulation methods. Usually, human subjects or manikins are used in field studies involving measurement techniques. However, as an alternative to full-scale measurement, Computational Fluid Dynamics (CFD) has been proven to be a practical and valuable tool for predicting the airflow field. At the same time, the accuracy of the predictions of the local airflow within the microclimate of the occupant is highly dependent on the proper modelling of the occupant itself. The human body not only has a complicated physical shape, but also has complex thermo-physiological properties. Modelling of all these aspects is a formidable challenge and an extremely time-consuming task. Therefore, various simplifications have been made in order to decrease the level of complexity so that the computation may be performed with the available computer resources. This paper reports the results of a detail numerical simulation to study the impact of occupant modelling on the airflow and temperature distribution and their influences on the occupant's thermal comfort. First, the predictions made by the CFD model were compared with experimental data that were measured in a specially designed experimental chamber. Good agreement was observed. Four type of configuration were used to model the occupant: a conventional block form, three-node, six-node and finally eight-node configurations. Further simulations were carried out to investigate the assumption of uniform heat distribution. An assessment of uniform and non-uniform heat distribution scenarios for various occupant configurations and ventilation systems showed that the assumption of uniform heat distribution is valid for a wide range of operating conditions.</p
Fabrication and assembly of thermoplastic microfluidics; a review
No full textVarious fields within biomedical engineering have been afforded rapid scientific advancement through the incorporation of microfluidics. As literature surrounding biological systems become more comprehensive and many microfluidic platforms show potential for commercialization, the development of representative fluidic systems has become more intricate. This has brought increased scrutiny towards the material properties of microfluidic substrates. Thermoplastics have been highlighted as a promising material, given their material adaptability and commercial compatibility. This review provides a comprehensive discussion surrounding recent developments pertaining to thermoplastic microfluidic device fabrication. Existing and emerging approaches related to both microchannel fabrication and device assembly are highlighted, with consideration towards how specific approaches induce physical and/or chemical properties that are optimally suited for relevant real-world applications
- …
