Hybrid flow through microchannels for blood cell separation

Cancer is considered to be the second cause of death in the Canada and other parts of the world. Separation of cancer cells from blood for early detection of cancer improves prognostics of survivals for most of types of cancer. In this thesis, design and fabrication of microdevices for living cell separation based on dielectrophoresis phenomena is presented. A novel microfluidic device for continuous separation of malignant cells from blood is fabricated and experimentally tested. The separation of breast cancer cells from blood using the microdevice is performed experimentally and reached close to 100% accuracy with a flow rate 01 mL/hr. Parallel configuration of the presented microdevice is recommended to increase the separation speed which will enable point-of-care tests. The effects of dielectrophoretic manipulation and carbon nanotubes on living cells are also investigated in the present work. The changes in genes expression due to the exposure to AC field of 10 kHz and 100 kHz and carbon nanotubes treatment are studied using microarray analysis. Results show that 75% of the studied genes were altered by the exposure to 10 KHz field and only 25% of the genes were slightly altered by the 100 kHz exposure. As a result, higher AC frequency in range of 100 kHz is recommended for dielectrophoretic applications. Moreover, important genes are reported to be altered by carbon nanotubes. Due to the fact that dielectrophoretic separation of living cells requires knowledge of the strength and distribution of electric field, analytical solutions for dielectrophoretic force over non-uniform interdigitated electrodes and for moving dielectrophoretic phenomenon are derived. Novel method to approximate the function that describes the potential profile between adjacent electrodes is reported. Excellent agreement is found by comparing the analytical solution with numerical and experimental results. A number of designs for the microfluidic chip were completed and experimental work carried out with living cells form cell lines being separated from blood. The experimental results suit the analytical findings and the method could be used in clinical studies

Kinematic Performance Measures and Optimization of Parallel Kinematics Manipulators: A Brief Review

This chapter covers a number of kinematic performance indices that are instrumental in designing parallel kinematics manipulators. These indices can be used selectively based on manipulator requirements and functionality. This would provide the very practical tool for designers to approach their needs in a very comprehensive fashion. Nevertheless, most applications require a more composite set of requirements that makes optimizing performance more challenging. The later part of this chapter will discuss single-objective and multi-objectives optimization that could handle certain performance indices or a combination of them. A brief description of most common techniques in the literature will be provided

Travelling Surface Acoustic Waves Microfluidics

AbstractIn this paper, we demonstrate the working principle of travelling surface acoustic waves (TSAWs) in a microfluidic system. The TSAWs were incorporated to separate polystyrene (PS) particles of variable diameters and perform controlled mixing of different chemicals for concentration gradient generation, both inside a polydimethylsiloxane (PDMS) microfluidic channel. The TSAWs generated an acoustic streaming flow (ASF) upon coupling with a liquid and exerted an acoustic radiation force (ARF) on the suspended particles. The ARF was theoretically estimated for PS microspheres suspended in water, and conditions for ARF dominance over ASF or vice versa were identified. Recently reported TSAW-based PS particles separation and gradient generation results by our group are summarized here

Impact of single-walled carbon nanotubes on the embryo: a brief review

Carbon nanotubes (CNTs) are considered one of the most interesting materials in the 21st century due to their unique physiochemical characteristics and applicability to various industrial products and medical applications. However, in the last few years, questions have been raised regarding the potential toxicity of CNTs to humans and the environment; it is believed that the physiochemical characteristics of these materials are key determinants of CNT interaction with living cells and hence determine their toxicity in humans and other organisms as well as their embryos. Thus, several recent studies, including ours, pointed out that CNTs have cytotoxic effects on human and animal cells, which occur via the alteration of key regulator genes of cell proliferation, apoptosis, survival, cell–cell adhesion, and angiogenesis. Meanwhile, few investigations revealed that CNTs could also be harmful to the normal development of the embryo. In this review, we will discuss the toxic role of single-walled CNTs in the embryo, which was recently explored by several groups including ours.the Canadian Institutes for Health Research, the Cancer Research Society Inc. of Canada, the National Colorectal Cancer Campaign, the Fonds de la Recherche en Santé du Québec (FRSQ-Réseau du Cancer), and by the College of Medicine at Qatar University

Droplet Coalescence by Selective Wettability Enhancement in Microfluidic Devices

A new approach for droplet coalescence in microfluidic channels based on selective surface energy alteration is demonstrated. The proposed method involves patterning the surface of cyclic olefin copolymer (COC), a hydrophobic substrate attached to a polydimethylsiloxane hydrophobic microchannel, with graphene oxide (GO) using standard microfabrication techniques. Surface wettability and adhesion analyses confirmed the enhancement of the COC surface energy upon GO patterning and the stability of the GO film on COC. Three representative cases are illustrated to demonstrate the effectiveness of the method on the coalescence of droplets for different droplet flow regimes, as well as the effect of changing the size of the patterned surface area on the fusion process. The method achieves droplet coalescence without the need for precise synchronization

Transforming medical device biofilm control with surface treatment using microfabrication techniques.

Biofilm deposition on indwelling medical devices and implanted biomaterials is frequently attributed to the prevalence of resistant infections in humans. Further, the nature of persistent infections is widely believed to have a biofilm etiology. In this study, the wettability of commercially available indwelling medical devices was explored for the first time, and its effect on the formation of biofilm was determined in vitro. Surprisingly, all tested indwelling devices were found to be hydrophilic, with surface water contact angles ranging from 60° to 75°. First, we established a thriving Candida albicans biofilm growth at 24 hours. in YEPD at 30°C and 37°C plus serum in vitro at Cyclic olefin copolymer (COC) modified surface, which was subsequently confirmed via scanning electron microscopy, while their cellular metabolic function was assessed using the XTT cell viability assay. Surfaces with patterned wettability show that a contact angle of 110° (hydrophobic) inhibits C. albicans planktonic and biofilm formation completely compared to robust growth at a contact angle of 40° (hydrophilic). This finding may provide a novel antimicrobial strategy to prevent biofilm growth and antimicrobial resistance on indwelling devices and prosthetic implants. Overall, this study provides valuable insights into the surface characteristics of medical devices and their potential impact on biofilm formation, leading to the development of improved approaches to control and prevent microbial biofilms and re-infections