On-chip Magnetoresistive Sensors for Detection and Localization of Paramagnetic Particles

This paper presents the work towards miniaturized magnetic biosensor array based on the detection of paramagnetic particles using the giant magnetoresistance (GMR) effect. GMR sensors have been studied for many years, but its application for on-chip integration and in complex configurations, as well as effective localization for Lab-On-Chip and Tissue Engineering applications is not yet explored. This work demonstrates the development of initial prototypes of 5 and 9 sensor GMR arrays of varying geometries and corresponding calibration and localization algorithms to detect and localize paramagnetic materials in 2D. The generation of a uniform magnetic field using a 16 magnet Halbach cylinder was also analyzed and optimized using FEA for different sensor configurations. Results show excellent localization for the fully calibrated 5 sensor arrays, with a mean (SD) error of 2.45 (1.61) mm for the ferrofluid as compared to 1.48 (1.14) mm for a strong ferromagnet for a 25×25mm2 array surface. The 9sensor array similarly showed good results for full calibration

Ultrafast Microfluidic Immunoassays Towards Real-time Intervention of Cytokine Storms

Biomarker-guided precision medicine holds great promise to provide personalized therapy with a good understanding of the molecular or cellular data of an individual patient. However, implementing this approach in critical care uniquely faces enormous challenges as it requires obtaining “real-time” data with high sensitivity, reliability, and multiplex capacity near the patient’s bedside in the quickly evolving illness. Current immunodiagnostic platforms generally compromise assay sensitivity and specificity for speed or face significantly increased complexity and cost for highly multiplexed detection with low sample volume. This thesis introduces two novel ultrafast immunoassay platforms: one is a machine learning-based digital molecular counting assay, and the other is a label-free nano-plasmonic sensor integrated with an electrokinetic mixer. Both of them incorporate microfluidic approaches to pave the way for near-real-time interventions of cytokine storms. In the first part of the thesis, we present an innovative concept and the theoretical study that enables ultrafast measurement of multiple protein biomarkers (<1 min assay incubation) with comparable sensitivity to the gold standard ELISA method. The approach, which we term “pre-equilibrium digital enzyme-linked immunosorbent assay” (PEdELISA) incorporates the single-molecular counting of proteins at the early, pre-equilibrium state to achieve the combination of high speed and sensitivity. We experimentally demonstrated the assay’s application in near-real-time monitoring of patients receiving chimeric antigen receptor (CAR) T-cell therapy and for longitudinal serum cytokine measurements in a mouse sepsis model. In the second part, we report the further development of a machine learning-based PEdELISA microarray data analysis approach with a significantly extended multiplex capacity using the spatial-spectral microfluidic encoding technique. This unique approach, together with a convolutional neural network-based image analysis algorithm, remarkably reduced errors faced by the highly multiplexed digital immunoassay at low analyte concentrations. As a result, we demonstrated the longitudinal data collection of 14 serum cytokines in human patients receiving CAR-T cell therapy at concentrations < 10pg/mL with a sample volume < 10 µL and 5-min assay incubation. In the third part, we demonstrate the clinical application of a machine learning-based digital protein microarray platform for rapid multiplex quantification of cytokines from critically ill COVID-19 patients admitted to the intensive care unit. The platform comprises two low-cost modules: (i) a semi-automated fluidic dispensing module that can be operated inside a biosafety cabinet to minimize the exposure of technician to the virus infection and (ii) a compact fluorescence optical scanner for the potential near-bedside readout. The automated system has achieved high interassay precision (~10% CV) with high sensitivity (<0.4pg/mL). Our data revealed large subject-to-subject variability in patient responses to anti-inflammatory treatment for COVID-19, reaffirming the need for a personalized strategy guided by rapid cytokine assays. Lastly, an AC electroosmosis-enhanced localized surface plasmon resonance (ACE-LSPR) biosensing device was presented for rapid analysis of cytokine IL-1β among sepsis patients. The ACE-LSPR device is constructed using both bottom-up and top-down sensor fabrication methods, allowing the seamless integration of antibody-conjugated gold nanorod (AuNR) biosensor arrays with microelectrodes on the same microfluidic platform. Applying an AC voltage to microelectrodes while scanning the scattering light intensity variation of the AuNR biosensors results in significantly enhanced biosensing performance. The technologies developed have enabled new capabilities with broad application to advance precision medicine of life-threatening acute illnesses in critical care, which potentially will allow the clinical team to make individualized treatment decisions based on a set of time-resolved biomarker signatures.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163129/1/yujing_1.pd

Biosensors to Monitor Cell Activity in 3D Hydrogel-Based Tissue Models

Three-dimensional (3D) culture models have gained relevant interest in tissue engineering and drug discovery owing to their suitability to reproduce in vitro some key aspects of human tissues and to provide predictive information for in vivo tests. In this context, the use of hydrogels as artificial extracellular matrices is of paramount relevance, since they allow closer recapitulation of (patho)physiological features of human tissues. However, most of the analyses aimed at characterizing these models are based on time-consuming and endpoint assays, which can provide only static and limited data on cellular behavior. On the other hand, biosensing systems could be adopted to measure on-line cellular activity, as currently performed in bi-dimensional, i.e., monolayer, cell culture systems; however, their translation and integration within 3D hydrogel-based systems is not straight forward, due to the geometry and materials properties of these advanced cell culturing approaches. Therefore, researchers have adopted different strategies, through the development of biochemical, electrochemical and optical sensors, but challenges still remain in employing these devices. In this review, after examining recent advances in adapting existing biosensors from traditional cell monolayers to polymeric 3D cells cultures, we will focus on novel designs and outcomes of a range of biosensors specifically developed to provide real-time analysis of hydrogel-based cultures

CMOS and MEMS Based Microsystems for Manipulation and Detection of Magnetic Beads for Biomedical Applications

RÉSUMÉ Les micro et nano billes magnétiques dédiées à l'étiquetage des bio-particules attirent de plus en plus d'intérêt dans de nombreuses applications environnementales et sanitaires, tels que l'analyse de gènes, le transport des médicaments, la purification et l'immunologie. Les dimensions réduites et la haute sensibilité des billes magnétiques rendent leurs manipulations à haute précision possibles. Leur simplicité de suivi dans le milieu biologique et leur biocompatibilité permettent d’effectuer des détections rapides et à haute sensibilité pour des applications in vivo et in vitro. L'utilisation traditionnelle des billes magnétiques prend place dans un laboratoire se servant du matériel encombrant et dispendieux. Avec le développement de la technologie de microfabrication, des billes magnétiques peuvent être traitées dans un microsystème, plus précisément, dans une structure laboratoire sur puce (LoC). La combinaison microfluidique et microélectronique offre des possibilités d’autoévaluation, ce qui peut augmenter l'efficacité du travail. Cette thèse est orientée vers de nouvelles approches pour la manipulation et la détection de bio-particules se servant de la technologie de microsystèmes basées sur des structures microelectroniques et microfluidiques et en utilisant des marqueurs de billes magnétiques. Basé sur un réseau de microbobines à la fois comme une source de champ magnétique et un capteur inductif, le microsystème proposé est réalisé grâce à l'efficacité de fabrication de structures CMOS-MEMS, ainsi que des circuits intégrés dédiés CMOS de haute performance afin d'obtenir un rendement élevé de manipulation et de détection de billes magnétiques. Plusieurs défis ont été analysés dans la mise en œuvre de ces microsystèmes et des solutions correspondantes fournies. Plus précisément, la conception et la mise en œuvre d'une plate-forme contrôlée en température en format portable sont d'abord présentées, dans un effort réalisé pour résoudre la question de la chaleur par effet Joule lors de l'application du réseau de microbobines comme une source de champ magnétique dédié à la manipulation de billes magnétiques. Une plateforme similaire à cette dernière a été améliorée pour effectuer une analyse magnétique immunologique, en ajoutant des circuits de détection par des billes magnétiques. De plus, des IgG et anti-IgG de souris ont été utilisés dans des expériences pour vérifier les performances de détection de la plateforme de microsystème proposé.----------ABSTRACT Magnetic micro/nano beads as labels of bio-particles have been attracting more and more interest in many environmental and health applications, such as gene and drug delivery, purification, and immunoassay. The miniature size and high sensitivity of magnetic bead allow accurate manipulation, whereas its high distinguishability from biological background and biocompatibility make fast and high sensitivity detection possible for in vitro and in vivo applications. Traditional employment of magnetic beads is done in laboratory environment with the assist of bulky and expensive equipment. Thanks to the development of microfabrication technology, magnetic beads therefore can be handled on a microsystem, more specifically, a Lab-on-Chip (LoC). The combination of microfluidics with microelectronics offers the possibility of automatic analyses, which can liberate the labor and increase the efficiency.This thesis focuses on new approaches for bio-particles manipulation and detection on microelectronic/microfluidic hybrid microsystems using magnetic beads as labels. Based on planar microcoil array as both magnetic field source and the front-end inductive sensor, the proposed microsystems can take advantage of the massive producible CMOS/MEMS fabrication process, as well as the customized high performance CMOS circuits, to achieve a high efficient magnetic beads manipulation and a quantitative detection. Several challenges in implementing such microsystems are analyzed and corresponding solutions are provided. Specifically, the design and implementation of a temperature controllable LoC platform in portable format is firstly presented, for the sake of resolving the Joule heat issue when applying microcoil array as magnetic field source in magnetic beads manipulation. The similar platform is then improved to be used for magnetic immunoassay, by adding magnetic beads sensing circuits. Mouse IgG and anti-mouse IgG are employed in experiments to verify the detection performance of the proposed microsystem platform. Additionally, a fully integrated silicon substrate MEMS chip which integrates both microfluidic channel and microcoil array on a single chip is designed and fabricated following the Finite Element Analysis (FEA) simulation results and tested using bio-particles attached magnetic beads. This monolithic chip has the potential to be applied for in vivo applications

Lab-on-a-Chip Fabrication and Application

The necessity of on-site, fast, sensitive, and cheap complex laboratory analysis, associated with the advances in the microfabrication technologies and the microfluidics, made it possible for the creation of the innovative device lab-on-a-chip (LOC), by which we would be able to scale a single or multiple laboratory processes down to a chip format. The present book is dedicated to the LOC devices from two points of view: LOC fabrication and LOC application

Integration of virus-like particle macromolecular bioreceptors in electrochemical biosensors

Rapid, sensitive and selective detection of chemical hazards and biological pathogens has shown growing importance in the fields of homeland security, public safety and personal health. In the past two decades, efforts have been focusing on performing point-of-care chemical and biological detections using miniaturized biosensors. These sensors convert target molecule binding events into measurable electrical signals for quantifying target molecule concentration. However, the low receptor density and the use of complex surface chemistry in receptors immobilization on transducers are common bottlenecks in the current biosensor development, adding to the cost, complexity and time. This dissertation presents the development of selective macromolecular Tobacco mosaic virus-like particle (TMV VLP) biosensing receptor, and the microsystem integration of VLPs in microfabricated electrochemical biosensors for rapid and performance-enhanced chemical and biological sensing. Two constructs of VLPs carrying different receptor peptides targeting at 2,4,6-trinitrotoluene (TNT) explosive or anti-FLAG antibody are successfully bioengineered. The VLP-based TNT electrochemical sensor utilizes unique diffusion modulation method enabled by biological binding between target TNT and receptor VLP. The method avoids the influence from any interfering species and environmental background signals, making it extremely suitable for directly quantifying the TNT level in a sample. It is also a rapid method that does not need any sensor surface functionalization process. For antibody sensing, the VLPs carrying both antibody binding peptides and cysteine residues are assembled onto the gold electrodes of an impedance microsensor. With two-phase immunoassays, the VLP-based impedance sensor is able to quantify antibody concentrations down to 9.1 ng/mL. A capillary microfluidics and impedance sensor integrated microsystem is developed to further accelerate the process of VLP assembly on sensors and improve the sensitivity. Open channel capillary micropumps and stop-valves facilitate localized and evaporation-assisted VLP assembly on sensor electrodes within 6 minutes. The VLP-functionalized impedance sensor is capable of label-free sensing of antibodies with the detection limit of 8.8 ng/mL within 5 minutes after sensor functionalization, demonstrating great potential of VLP-based sensors for rapid and on-demand chemical and biological sensing

Micro/nanofluidic and lab-on-a-chip devices for biomedical applications

Micro/Nanofluidic and lab-on-a-chip devices have been increasingly used in biomedical research [1]. Because of their adaptability, feasibility, and cost-efficiency, these devices can revolutionize the future of preclinical technologies. Furthermore, they allow insights into the performance and toxic effects of responsive drug delivery nanocarriers to be obtained, which consequently allow the shortcomings of two/three-dimensional static cultures and animal testing to be overcome and help to reduce drug development costs and time [2–4]. With the constant advancements in biomedical technology, the development of enhanced microfluidic devices has accelerated, and numerous models have been reported. Given the multidisciplinary of this Special Issue (SI), papers on different subjects were published making a total of 14 contributions, 10 original research papers, and 4 review papers. The review paper of Ko et al. [1] provides a comprehensive overview of the significant advancements in engineered organ-on-a-chip research in a general way while in the review presented by Kanabekova and colleagues [2], a thorough analysis of microphysiological platforms used for modeling liver diseases can be found. To get a summary of the numerical models of microfluidic organ-on-a-chip devices developed in recent years, the review presented by Carvalho et al. [5] can be read. On the other hand, Maia et al. [6] report a systematic review of the diagnosis methods developed for COVID-19, providing an overview of the advancements made since the start of the pandemic. In the following, a brief summary of the research papers published in this SI will be presented, with organs-on-a-chip, microfluidic devices for detection, and device optimization having been identified as the main topics.info:eu-repo/semantics/publishedVersio

Development of Smartphone dual-laser waveguide based fluorescent microscopy system using 3D printing

Nowadays cellphones are present everywhere, and along with the worldwide network of devices, the concept of mobile health monitoring is changing to reshape the biosensor market. The smartphone’s camera is a proven reliable candidate as a detector for the studies performed by various research groups. This study is a proof of concept of the Smartphone detection of two fluorescent dyes which can be used as biomarkers for point-of-care diagnostics through image processing techniques. A smartphone Xiaomi Redmi Note 4 along with two fluorescent dyes DyLight™ 405 NHS Ester and DyLight™ 633 NHS Ester are used in conjunction with two lasers Thorlabs 405 nm and 638nm. The captured pictures were analyzed using Image J. The limit of detection and dynamic range values were calculated for both dyes, 28.39 nM and 20-800 nM for DyLight™ 405 NHS Ester dye and 15.85 nM and 10-600 nM for DyLight™ 633 NHS Ester dye. Then this concept is realized by developing a cheap 3D printed POC device which uses the optical microscopy technology along with a PDMS chip. Hence, this integrated novel innovation which prioritizes accuracy and the ease of usage, can be a game changer for patients who live in countries of limited resources and can moreover aid to the impoverished people who are in dire need of medical help