BioScript: programming safe chemistry on laboratories-on-a-chip

This paper introduces BioScript, a domain-specific language (DSL) for programmable biochemistry which executes on emerging microfluidic platforms. The goal of this research is to provide a simple, intuitive, and type-safe DSL that is accessible to life science practitioners. The novel feature of the language is its syntax, which aims to optimize human readability; the technical contributions of the paper include the BioScript type system and relevant portions of its compiler. The type system ensures that certain types of errors, specific to biochemistry, do not occur, including the interaction of chemicals that may be unsafe. The compiler includes novel optimizations that place biochemical operations to execute concurrently on a spatial 2D array platform on the granularity of a control flow graph, as opposed to individual basic blocks. Results are obtained using both a cycle-accurate microfluidic simulator and a software interface to a real-world platform

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

Micro- and Nanofluidics for Bionanoparticle Analysis

Bionanoparticles such as microorganisms and exosomes are recoganized as important targets for clinical applications, food safety, and environmental monitoring. Other nanoscale biological particles, includeing liposomes, micelles, and functionalized polymeric particles are widely used in nanomedicines. The recent deveopment of microfluidic and nanofluidic technologies has enabled the separation and anslysis of these species in a lab-on-a-chip platform, while there are still many challenges to address before these analytical tools can be adopted in practice. For example, the complex matrices within which these species reside in create a high background for their detection. Their small dimension and often low concentration demand creative strategies to amplify the sensing signal and enhance the detection speed. This Special Issue aims to recruit recent discoveries and developments of micro- and nanofluidic strategies for the processing and analysis of biological nanoparticles. The collection of papers will hopefully bring out more innovative ideas and fundamental insights to overcome the hurdles faced in the separation and detection of bionanoparticles

Cellulose-Based Biosensing Platforms

Cellulose empowers measurement science and technology with a simple, low-cost, and highly transformative analytical platform. This book helps the reader to understand and build an overview of the state of the art in cellulose-based (bio)sensing, particularly in terms of the design, fabrication, and advantageous analytical performance. In addition, wearable, clinical, and environmental applications of cellulose-based (bio)sensors are reported, where novel (nano)materials, architectures, signal enhancement strategies, as well as real-time connectivity and portability play a critical role

Development of a biosensor system to detect bacteria in food systems

The development of biosensors may assist for the on-site detection of foodborne pathogens. The overall goal of this study was to develop a biosensor system for detecting Listeria innocua (non-pathogenic surrogate bacteria used as a model for pathogenic Listeria monocytogenes) in food systems. The study was divided into three main parts: (1) development of a sample collection and interface system for Listeria innocua from food samples, (2) development of a sample concentration system for the collected bacteria prior detection, and (3) development of a detection system based on a carbon nanotube potentiometric biosensor for a quantitative detection of Listeria innocua. In the second chapter, we discussed a sample collection protocol and delivery system developed for bacteria from food surfaces. Listeria innocua was used for testing and illustration. For this purpose, the surface of meat samples was inoculated with Listeria innocua at different concentrations from 10^1-10^5 CFU/mL. Then, cellulose membranes were applied to the surface of products for different times: 5, 10, 15, 20, 25, and 30 min sampling. The cellulose membranes were analyzed for their suitability for bacteria enumeration using a plating method for Listeria innocua. It was observed that sampling times between 5-10 min were the best and collection of \u3e80% of bacteria from the food’s surface was achieved. In the third chapter we discussed a microfluidic device for concentration of biological samples based on removal of liquids by hydrogel films. The performance of the device was demonstrated by concentrating 1-5 µm fluorescent beads followed by concentration of bacteria samples such as Listeria innocua. Results showed that fluorescence intensity of the beads was increased by 10 times at the end of concentration. Recovery efficiencies of 85.60 and 91.75 % were obtained for initial bacteria concentrations of 1x10^1 and 1x10^2 CFU/mL. Moreover, cell counts were observed to increase by up to 10 times at the end of concentration. This study showed that the concentrator device successfully concentrated the samples and no significant loss of living cells was observed for most of the bacteria concentrations. A carbon nanotube potentiometric biosensor for the detection of bacteria from food samples was demonstrated in the fourth chapter. The biosensor was constructed by depositing carboxylic acid (–COOH) functionalized single walled carbon nanotubes (SWCNTs) on a glassy carbon electrode (GCE), followed by the attachment of anti-Listeria antibodies to the SWCNTs between the amine groups and the –COOH by covalent functionalization using EDC/Sulfo-NHS chemistry. The performance of the biosensor was evaluated at various concentrations of L. innocua, for factors such as limit of detection, sensitivity, response time, linearity, and selectivity. In addition, the application of the complete detection system based on sample collection, concentration and detection of bacteria from food samples such as meat and milk was evaluated. Results showed that the system could successfully detect L. innocua with a linear response between electromotive force (EMF/voltage) and bacteria concentrations and a lower limit of detection of 11 CFU/mL. Additionally, similar results were obtained from the biosensor system for L. innocua from food samples

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

Electrochemical microfluidic multiplexed biosensor platform for point-of-care testing

Early and accurate diagnosis of a specific disease plays a decisive role for its effective treatment. However, in many cases the clinical findings, based on a single biomarker detection alone, are not sufficient for the appropriate diagnosis as well as monitoring of its treatment. Furthermore, it is highly desirable to screen multi-analytes (e.g. various diseases and drugs) at the same time enabling a low-cost, quick and reliable quantification. Thus, multiplexing, simultaneous detection of different analytes from a single sample, has become in recent years essential for diagnostics, especially for point-of-care testing (POCT). This thesis focuses on the scientific issue regarding the sensitivity enhancement of microfluidic biosensor platforms. Simulations, design studies and experiments are employed to investigate the interplay between the immobilization area and the resulting sensitivity. Thereby, a novel concept comprising design rules for microfluidic biosensors using the stop-flow technique has been introduced. In combination with different technical measures it allows the realization of an electrochemical lab-on-a-chip (LOC) platform for the fast, sensitive and simultaneous POCT in clinically relevant samples. This system employs a universally applicable, bioaffinity based biomolecule immobilization along with an amperometric readout. By means of the dry film photoresist technology, the fabrication of disposable microfluidic biosensors is enabled with high yield on wafer-level. The presented LOC platform offers three different biosensors with a microfluidic channel network of two, four or eight discrete immobilization sections, each with a volume of 680  nl. They can be actuated by individual channel inlets allowing a high flexibility in the assay design with respect to its format (e.g. competitive) and its technology (e.g. genomics). The feasibility for multiplexing is successfully demonstrated with DNA-based antibiotic assays for tetracycline and streptogramin, both important growth promoters in livestock breeding. The extensive usage of antibiotics is one of the major causes of the multi-drug-resistant bacteria and so, it has to be kept under surveillance. This platform allows the simultaneous POCT of different antibiotics from human plasma along with a limit of detection of less than 10  ng  ml⁻¹, a wide working range up to 1,600  ng ml⁻¹ and inter-assay precisions of about 10  %. Moreover, the microfluidic LOC system provides a low consumption of reagent and sample, reduces the total assay time drastically with a sample-to-result time of only 10  min. The shelf-life of the biosensors is proven to be at least 3 months at +4  °C. The introduced design concept with specific technical measures facilitates the implementation of microfluidic multiplexed biosensors in a low-cost, compact, and at the same time sensitive manner. This platform targets the POCT in the first place, yet, owing to its multiplexing approach it can be expanded for in vitro diagnostics

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

A portable device for time-resolved fluorescence based on an array of CMOS SPADs with integrated microfluidics

[eng] Traditionally, molecular analysis is performed in laboratories equipped with desktop instruments operated by specialized technicians. This paradigm has been changing in recent decades, as biosensor technology has become as accurate as desktop instruments, providing results in much shorter periods and miniaturizing the instrumentation, moving the diagnostic tests gradually out of the central laboratory. However, despite the inherent advantages of time-resolved fluorescence spectroscopy applied to molecular diagnosis, it is only in the last decade that POC (Point Of Care) devices have begun to be developed based on the detection of fluorescence, due to the challenge of developing high-performance, portable and low-cost spectroscopic sensors. This thesis presents the development of a compact, robust and low-cost system for molecular diagnosis based on time-resolved fluorescence spectroscopy, which serves as a general-purpose platform for the optical detection of a variety of biomarkers, bridging the gap between the laboratory and the POC of the fluorescence lifetime based bioassays. In particular, two systems with different levels of integration have been developed that combine a one-dimensional array of SPAD (Single-Photon Avalanch Diode) pixels capable of detecting a single photon, with an interchangeable microfluidic cartridge used to insert the sample and a laser diode Pulsed low-cost UV as a source of excitation. The contact-oriented design of the binomial formed by the sensor and the microfluidic, together with the timed operation of the sensors, makes it possible to dispense with the use of lenses and filters. In turn, custom packaging of the sensor chip allows the microfluidic cartridge to be positioned directly on the sensor array without any alignment procedure. Both systems have been validated, determining the decomposition time of quantum dots in 20 nl of solution for different concentrations, emulating a molecular test in a POC device.[cat] Tradicionalment, l'anàlisi molecular es realitza en laboratoris equipats amb instruments de sobretaula operats per tècnics especialitzats. Aquest paradigma ha anat canviant en les últimes dècades, a mesura que la tecnologia de biosensor s'ha tornat tan precisa com els instruments de sobretaula, proporcionant resultats en períodes molt més curts de temps i miniaturitzant la instrumentació, permetent així, traslladar gradualment les proves de diagnòstic fora de laboratori central. No obstant això i malgrat els avantatges inherents de l'espectroscòpia de fluorescència resolta en el temps aplicada a la diagnosi molecular, no ha estat fins a l'última dècada que s'han començat a desenvolupar dispositius POC (Point Of Care) basats en la detecció de la fluorescència, degut al desafiament que suposa el desenvolupament de sensors espectroscòpics d'alt rendiment, portàtils i de baix cost. Aquesta tesi presenta el desenvolupament d'un sistema compacte, robust i de baix cost per al diagnòstic molecular basat en l'espectroscòpia de fluorescència resolta en el temps, que serveixi com a plataforma d'ús general per a la detecció òptica d'una varietat de biomarcadors, tancant la bretxa entre el laboratori i el POC dels bioassaigs basats en l'anàlisi de la pèrdua de la fluorescència. En particular, s'han desenvolupat dos sistemes amb diferents nivells d'integració que combinen una matriu unidimensional de píxels SPAD (Single-Photon Avalanch Diode) capaços de detectar un sol fotó, amb un cartutx microfluídic intercanviable emprat per inserir la mostra, així com un díode làser UV premut de baix cost com a font d'excitació. El disseny orientat a la detecció per contacte de l'binomi format pel sensor i la microfluídica, juntament amb l'operació temporitzada dels sensors, permet prescindir de l'ús de lents i filtres. Al seu torn, l'empaquetat a mida de l'xip sensor permet posicionar el cartutx microfluídic directament sobre la matriu de sensors sense cap procediment d'alineament. Tots dos sistemes han estat validats determinant el temps de descomposició de "quantum dots" en 20 nl de solució per a diferents concentracions, emulant així un assaig molecular en un dispositiu POC