TOPICAL REVIEW: Microfluidics for flow cytometric analysis of cells and particles

This review describes recent developments in microfabricated flow cytometers and related microfluidic devices that can detect, analyze, and sort cells or particles. The high-speed analytical capabilities of flow cytometry depend on the cooperative use of microfluidics, optics and electronics. Along with the improvement of other components, replacement of conventional glass capillary-based fluidics with microfluidic sample handling systems operating in microfabricated structures enables volume- and power-efficient, inexpensive and flexible analysis of particulate samples. In this review, we present various efforts that take advantage of novel microscale flow phenomena and microfabrication techniques to build microfluidic cell analysis systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49182/2/pm5_3_r02.pd

Micromachines for Dielectrophoresis

An outstanding compilation that reflects the state-of-the art on Dielectrophoresis (DEP) in 2020. Contributions include: - A novel mathematical framework to analyze particle dynamics inside a circular arc microchannel using computational modeling. - A fundamental study of the passive focusing of particles in ratchet microchannels using direct-current DEP. - A novel molecular version of the Clausius-Mossotti factor that bridges the gap between theory and experiments in DEP of proteins. - The use of titanium electrodes to rapidly enrich T. brucei parasites towards a diagnostic assay. - Leveraging induced-charge electrophoresis (ICEP) to control the direction and speed of Janus particles. - An integrated device for the isolation, retrieval, and off-chip recovery of single cells. - Feasibility of using well-established CMOS processes to fabricate DEP devices. - The use of an exponential function to drive electrowetting displays to reduce flicker and improve the static display performance. - A novel waveform to drive electrophoretic displays with improved display quality and reduced flicker intensity. - Review of how combining electrode structures, single or multiple field magnitudes and/or frequencies, as well as variations in the media suspending the particles can improve the sensitivity of DEP-based particle separations. - Improvement of dielectrophoretic particle chromatography (DPC) of latex particles by exploiting differences in both their DEP mobility and their crossover frequencies

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

Microdevices and Microsystems for Cell Manipulation

Microfabricated devices and systems capable of micromanipulation are well-suited for the manipulation of cells. These technologies are capable of a variety of functions, including cell trapping, cell sorting, cell culturing, and cell surgery, often at single-cell or sub-cellular resolution. These functionalities are achieved through a variety of mechanisms, including mechanical, electrical, magnetic, optical, and thermal forces. The operations that these microdevices and microsystems enable are relevant to many areas of biomedical research, including tissue engineering, cellular therapeutics, drug discovery, and diagnostics. This Special Issue will highlight recent advances in the field of cellular manipulation. Technologies capable of parallel single-cell manipulation are of special interest

Microfluidic Blood Cell Sorting: Now and Beyond

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106971/1/smll201302907.pd

Assessing the effects of radiotherapy on head and neck squamous cell carcinoma using microfluidic techniques

ObjectiveThe aim of this study was to investigate how HNSCC tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device, respond to radiation treatment.Materials and Methods35 patients with HNSCC were recruited; in addition liver tissue from 5 Wistar rats was used. A glass microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimise the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5x2 Gy. Cell death was assessed in the tissue effluent using the soluble markers LDH and cytochrome c, and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Radiation-induced DNA strand breaks were detected using the TUNEL assay.ResultsA significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC it was seen after 40 Gy, compared to the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single dose radiation. There was a significant increase in apoptotic index between the non-irradiated HNSCC tissue and irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. As with the apoptotic index, there was a significant increase in radiation-induced DNA breaks between the non-irradiated and the irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy.ConclusionThis microfluidic technique can be used to study the effects of radiation on HNSCC tissue. The device was capable of maintaining the HNSCC in a viable state, without it undergoing significant apoptosis or DNA damage and can be used to demonstrate the relationship between radiotherapy dose and radiation-induced cell death using tissue-based cell death markers.This study is a significant step towards achieving the ultimate goal of developing this device as a tool, capable of predicting a patient’s response to radiotherapy prior to the commencement of treatment

Lab-on-Chip Microdevices for Capturing, Imaging and Counting White Blood Cells.

White blood cells (WBCs) and their subtypes are important constituents of the human immune system as their concentration, quantified by a WBC count test, indicates the state of body’s immune response against infections. These cell count tests are important prognostic and diagnostic indicators for a number of human immunological diseases, most prominent of them being AIDS. Flow cytometry (FC) is the gold standard for counting WBCs. Although high throughput and accurate, FC based instruments are bulky, expensive and require skillful and trained personnel for their operation and maintenance. This necessitates the development of inexpensive, portable point-of-care (POC) systems for capturing and enumerating WBCs and their subtypes. We envision a portable, point-of-care WBC counting system which can capture thousands of WBCs and simultaneously image and count them. Towards this end, we have developed: - A microfluidic biochip for trapping and counting WBCs. The biochip has a novel 3D cell trapping architecture and enables simultaneous capture and counting of thousands of WBCs. A WBC trapping efficiency of ~90% is achieved using the biochip. - Microlens arrays with a large field of view (FOV) imaging capability that have an optical performance (numerical aperture, resolution) equivalent to a conventional microscope objective. We envision that the cell trapping biochip and the microlens arrays proposed in this thesis can be integrated to perform simultaneous on-chip capture and imaging/counting of WBCs. The integrated microsystem can also be used as a generic platform for sorting and enumeration of different kinds of cells for disease diagnosis and research applications.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/96147/1/anuragt_1.pd