Microfluidics for Biosensing

There are 12 papers published with 8 research articles, 3 review articles and 1 perspective. The topics cover: Biomedical microfluidics Lab-on-a-chip Miniaturized systems for chemistry and life science (MicroTAS) Biosensor development and characteristics Imaging and other detection technologies Imaging and signal processing Point-of-care testing microdevices Food and water quality testing and control We hope this collection could promote the development of microfluidics and point-of-care testing (POCT) devices for biosensing

Bio-Micro-Systems for Diagnostic Applications, Disease Prevention and Creating Tools for Biological Research

This thesis, divided into two parts, describes the development of 5 novel Bio-Micro-System devices. The term Bio-Micro-System has been used here to describe BioMEMS and 3D printed devices, with the dimensions of key components ranging from micrometers to a millimeter. Part A is focused on ‘Medical’ Micro-System devices that can potentially solve common medical problems. Part B is focused on ‘Biological’ Micro-System devices/tools for facilitating/enabling biological research. Specifically, Part A describes two implantable, electronics-free intraocular pressure (IOP) microsensors for the medical management of glaucoma: 1) Near Infrared Fluorescence-based Optomechanical (NiFO) technology - Consists of an implantable, pressure sensor that ‘optically encodes’ pressure in the near infrared (NIR) regime. A non-implantable, portable and compact optical head is used to excite the sensor and collect the emitted NIR light. The thesis discusses optimized device architecture and microfabrication approaches for best performance commercialization. 2) Displacement based Contrast Imaging (DCI) technology - A proof of concept, fluid pressure sensing scheme is shown to operate over a pressure range of 0–100 mbar (∼2 mbar resolution between 0–20 mbar,∼10 mbar resolution between 20–100 mbar), with a maximum error of <7% throughout its dynamic range. The thesis introduces the DCI technology and discusses its application as an IOP sensor. Moreover, Part A also describes a Touch-activated Sanitizer Dispensing (TSD) system for combating community acquired infections. The TSD can be mounted on any surface that is exposed to high human traffic and consists of an array of human-powered, miniaturized valves that deliver a small amount of disinfectant when touch actuated. The device disinfects the person’s hand that is touching it while being self-sterilized at the same time. The thesis describes the design and implementation of a proof of concept TSD that can disinfect an area equivalent to the size of a thumb. A significant (~ 10 fold) reduction in microbiological load is demonstrated on the fingertip and device surface within the first 24 hours. The size and footprint of the TSD can be scaled up as needed to improve hand hygiene compliance. In Part B, we developed a microfluidic chip for immobilizing Drosophila melanogaster larva by creating a cold micro-environment around the larva. After characterizing on chip temperature distribution and larval body movement, results indicate that the method is appropriate for repetitive and reversible, short-term (several minutes) immobilization. The method offers the added advantage of using the same chip to accommodate and immobilize larvae across all developmental stages (1st instar-late 3rd instar). Besides the demonstrated applications of the chip in high resolution observation of sub cellular events such as mitochondrial trafficking in neurons and neuro-synaptic growth, we envision the use of this method in a wide variety of biological imaging studies employing the Drosophila larval system, including cellular development and other studies. Finally, Part B also describes a 3D printed millifluidic device for CO2 immobilization of Caenorhabditis elegans populations. We developed a novel 3D printed device for immobilizing populations of Caenorhabditis elegans by creating a localized CO2 environment while the animals are maintained on the surface of agar. The results indicate that the method is easy to implement, is appropriate for short-term (20 minutes) immobilization and allows recovery within a few minutes. We envision its use in a wide variety of biological studies in Caenorhabditis elegan, including cellular development and neuronal regeneration studies.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144050/1/amritarc_1.pd

Integrating droplet and digital microfluidics for single-cell analysis

The motivation to engineer biological systems through standardization and abstraction sparked the development of technological advances in automation of life sciences since the early 2000’s. Now, robotics are performing high-throughput tasks with increasingly higher precision and control over the environment of precious biological samples. At the same time, a different set of hardware has emerged in the life-sciences: while robotics enable for high-throughput automation, microfluidics - the discipline of handling fluids on a micro scale - allows researchers and clinicians to perform experiments they could not have imagined before. These highly controlled devices can purify proteins, engineer cells, gain insights to single-cell ‘omic’ information, or filter out a patient’s cancer cells in a fully automated fashion. In this work, we are focused on designing novel microfluidic devices for single-cell analysis. Currently, the use of single-cell analysis microfluidic devices open up the possibility of gaining detailed insights in heterozygosity of cell populations when coupled with next-generation sequencing technologies. We propose the design of a microfluidic setup that has improved control over single-cell operations within droplet-in-channel microfluidic architectures compared to current systems. Expanding these ’droplet digital’ tools, we have developed a microfluidic system for binary sorting of droplet libraries, on-demand droplet generation, droplet mixing, droplet storage and release, and deterministic encapsulation of single-cells . We propose new methods to sort cells, such as filamentous fungi libraries based on enzyme production, yeast based on growth rate and mammalian cell single-clones based on gene-editing efficiency. This work involves the development of novel hardware and software, and the integration of our microfluidic device within an automation system to operate dropletdigital microfluidics. Such systems are expanding the toolbox of those who are ‘engineering biology’

Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most common type of leukemia. The Cancer Genome Atlas Research Network has demonstrated the increasing genomic complexity of acute myeloid leukemia (AML). In addition, the network has facilitated our understanding of the molecular events leading to this deadly form of malignancy for which the prognosis has not improved over past decades. AML is a highly heterogeneous disease, and cytogenetics and molecular analysis of the various chromosome aberrations including deletions, duplications, aneuploidy, balanced reciprocal translocations and fusion of transcription factor genes and tyrosine kinases has led to better understanding and identification of subgroups of AML with different prognoses. Furthermore, molecular classification based on mRNA expression profiling has facilitated identification of novel subclasses and defined high-, poor-risk AML based on specific molecular signatures. However, despite increased understanding of AML genetics, the outcome for AML patients whose number is likely to rise as the population ages, has not changed significantly. Until it does, further investigation of the genomic complexity of the disease and advances in drug development are needed. In this review, leading AML clinicians and research investigators provide an up-to-date understanding of the molecular biology of the disease addressing advances in diagnosis, classification, prognostication and therapeutic strategies that may have significant promise and impact on overall patient survival

Single Cell Analysis

Cells are the most fundamental building block of all living organisms. The investigation of any type of disease mechanism and its progression still remains challenging due to cellular heterogeneity characteristics and physiological state of cells in a given population. The bulk measurement of millions of cells together can provide some general information on cells, but it cannot evolve the cellular heterogeneity and molecular dynamics in a certain cell population. Compared to this bulk or the average measurement of a large number of cells together, single-cell analysis can provide detailed information on each cell, which could assist in developing an understanding of the specific biological context of cells, such as tumor progression or issues around stem cells. Single-cell omics can provide valuable information about functional mutation and a copy number of variations of cells. Information from single-cell investigations can help to produce a better understanding of intracellular interactions and environmental responses of cellular organelles, which can be beneficial for therapeutics development and diagnostics purposes. This Special Issue is inviting articles related to single-cell analysis and its advantages, limitations, and future prospects regarding health benefits

Progenitor cells in auricular cartilage demonstrate promising cartilage regenerative potential in 3D hydrogel culture

The reconstruction of auricular deformities is a very challenging surgical procedure that could benefit from a tissue engineering approach. Nevertheless, a major obstacle is presented by the acquisition of sufficient amounts of autologous cells to create a cartilage construct the size of the human ear. Extensively expanded chondrocytes are unable to retain their phenotype, while bone marrow-derived mesenchymal stromal cells (MSC) show endochondral terminal differentiation by formation of a calcified matrix. The identification of tissue-specific progenitor cells in auricular cartilage, which can be expanded to high numbers without loss of cartilage phenotype, has great prospects for cartilage regeneration of larger constructs. This study investigates the largely unexplored potential of auricular progenitor cells for cartilage tissue engineering in 3D hydrogels