This PDF file contains the front matter associated with SPIE Proceedings Volume 8615, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

An optofluidic jet waveguide for on chip fluorescence analysis is presented. The waveguide consists of an high speed water jet produced by means of a micro-channel coupled with a multimode optical fiber collecting the fluorescence opportunely excited. The liquid jet acts, at the same time, as the solution to analyse and as an optical waveguide. This configuration allows a strong reduction of the scattering and fluorescence of non analyte substances enabling a very low limit of detection (LOD). The integrated device is fabricated by PMMA micro-machining allowing a self-alignment between the liquid jet waveguide and the optical fiber used to deliver the fluorescence to the detector. The performance of the system has been tested on Cy5 water solutions and LOD of 2.56 nM has been obtained. A proof-of-concept of filter-free measurements has been performed demonstrating that fluorescence measurements can be performed also by using a photodiode with an LOD of 6.11 nM.

A lab-in-fiber platform, comprising a photonic crystal fiber component for light-sample interaction, was experimentally demonstrated to be effective as a sensor and micro-reactor. Specifically, it enabled the discrimination between free and liposome-encapsulated fluorophores as well as allowed for the excitation of in-fiber plasmonic photothermal effects, by alternating between different fiber-coupled inputs. The significant increase in fluorescence emissions upon release of fluorophores, encapsulated within liposomes at self-quenching concentrations, was perceived as a shoulder in the device’s spectral output that otherwise only comprises the input excitation. Markedly, the observed shoulder was only discernible when the photonic crystal fiber was placed in a bent orientation. This was explained to be associated with the bending-induced refractive index profile changes in the fiber cross section that led to increased amounts of evanescent fields for light-sample interactions. Results highlighted the viability of the lab-in-fiber platform as an alternative to current lab-on-a-chip devices.

Aim of the paper is the orientation of research and development on a completely new approach to innovative in-field and point of care diagnostics in industry, biology and medicine. Central functional modules are smartphones and/or smart pads supplemented by additional hardware apps and software apps. Specific examples are given for numerous practical applications concerning optodigital instrumentations. The methodical classification distinguishes between different levels for combination of hardware apps (hwapps) and software apps (swapps) with smartphones and/or smartpads. These methods are fundamental enablers for the transformation from stationary conventional laboratory diagnostics into mobile innovative in-field and point of care diagnostics. The innovative approach opens so far untapped enormous markets due to the convenience, reliability and affordability of smartphone and/or smartpad instruments. A highly visible advantage of smartphones and/or smartpads is the huge number of their distribution, their worldwide connectivity via cloud services and the experienced capability of their users for practical operations.

Replacing animal testing with in vitro cocultures of human cells is a long-term goal in pre-clinical drug tests used to gain reliable insight into drug-induced cell toxicity. However, current state-of-the-art 2D or 3D cell cultures aiming at mimicking human organs in vitro still lack organ-like morphology and perfusion and thus organ-like functions. To this end, microfluidic systems enable construction of cell culture devices which can be designed to more closely resemble the smallest functional unit of organs. Multiphysics simulations represent a powerful tool to study the various relevant physical phenomena and their impact on functionality inside microfluidic structures. This is particularly useful as it allows for assessment of system functions already during the design stage prior to actual chip fabrication. In the HepaChip^®, dielectrophoretic forces are used to assemble human hepatocytes and human endothelial cells in liver sinusoid-like structures. Numerical simulations of flow distribution, shear stress, electrical fields and heat dissipation inside the cell assembly chambers as well as surface wetting and surface tension effects during filling of the microchannel network supported the design of this human-liver-on-chip microfluidic system for cell culture applications. Based on the device design resulting thereof, a prototype chip was injection-moulded in COP (cyclic olefin polymer). Functional hepatocyte and endothelial cell cocultures were established inside the HepaChip^® showing excellent metabolic and secretory performance.

MEMS human “organs-on-a-chip” can be used to create model human organ systems for developing new diagnostic and therapeutic strategies. They represent a promising new strategy for rapid testing of new diagnostic and therapeutic approaches without the need for involving risks to human subjects. We are developing multicomponent, superparamagnetic and fluorescent nanoparticles as X-ray and MRI contrast agents for noninvasive multimodal imaging and for antibody- or peptide-targeted drug delivery to tumor and precancerous cells inside these artificial organ MEMS devices. Magnetic fields can be used to move the nanoparticles “upstream” to find their target cells in an organs-on-achip model of human ductal breast cancer. Theoretically, unbound nanoparticles can then be removed by reversing the magnetic field to give a greatly enhanced image of tumor cells within these artificial organ structures. Using branched PDMS microchannels and 3D tissue engineering of normal and malignant human breast cancer cells inside those MEMS channels, we can mimic the early stages of human ductal breast cancer with the goal to improve the sensitivity and resolution of mammography and MRI of very small tumors and test new strategies for treatments. Nanomedical systems can easily be imaged by multicolor confocal microscopy inside the artificial organs to test targeting and therapeutic responses including the differential viability of normal and tumor cells during treatments. Currently we are using 2-dimensional MEMS structures, but these studies can be extended to more complex 3D structures using new 3D printing technologies.

Commonly, microfluidic devices are based on the movement of fluids. For molecular diagnostics assays which often include steps like PCR, this practically always involves a more or less complicated set of external pumps, valves and liquid controls. In the presented paper, we follow a different approach in which the fluid after sample introduction remains stationary and the main bioactive sample molecules are moved through a chain of reaction compartments which contain the different reagents necessary for the assay. The big advantage of this concept is the lack of any external fluid actuation/control. Results on sample carry-over experiments and complete assays will be given.

Multiple changes within the tumor microenvironment have been correlated with an increase in metastasis, yet the mechanisms are not fully understood. Tumor cells can be stimulated by the release of chemoattractant factors such as epidermal growth factor (EGF) from nearby stromal cells, resulting in increased intravasation and metastasis. Additionally, altered extracellular matrix density can result in changes in gene expression patterns governing increased cellular proliferation and motility. The Nano Intravital Device (NANIVID) has been used to produce gradients of select soluble factors in the tumor microenvironment and to study the role of these changes on cell migration. In previous studies, the NANIVID utilized a synthetic hydrogel to produce an EGF gradient to attract metastatic breast cancer cells. In this work, a matrigel insert will be introduced into the outlet to provide a substrate for cells to migrate on when entering the device. The concentration of the chemoattractant and matrigel comprising the insert will be optimized to produce a suitable gradient for inducing chemotaxis in metastatic breast cancer cells in vitro. Additionally, silk and alginate matrices will be explored as improved soluble factor release mediums. Delivery of larger molecules such as collagen cross-linkers requires an alternative hydrogel material. Future NANIVID experiments will utilize these materials to gauge the cellular motility response when a stiffer matrix is encountered.

Inkjet printing is a digital printing technique that is capable of depositing not only inks, but functional materials onto different substrates in an additive way. In this paper, applications of inkjet printed structures for microfluidic lab-on-chip systems are discussed. Such systems are promising for different chemical or biochemical analysis tasks carried out at the Point-of-Care level and therefore due to cost reasons are often fabricated from polymers. The paper discusses inkjetprinted wiring structures and electroactive polymer (EAP) actuators for use in microfluidic lab-on-chip systems. Silver and gold wirings are shown that are fabricated by printing metal nanoparticle inks onto polymer substrates. After printing the structures are sintered using argon plasma sintering, a low-temperature sintering process that is compatible with polymer substrates. The wirings consist of several electrode like structures and contact pads and feature minimum structure sizes of approximately 70 μm. They can be used for electrodes, fluid presence detectors and localized ohmic heaters in lab-on-chip systems. Based on that an all inkjet-printed EAP actuator then is discussed. Membrane-type bending actuators generate deflections of approximately 5 μm when being driven at a resonance frequency of 1.8 kHz with 110 V. Derived from that and assuming passive valves on-chip pumping rates in the range of 0.5 ml/min can be estimated.

Engineers who are developing microfluidic devices and bioMEMs for life science applications have many aspects to consider when selecting the proper base materials for constructing a device. While glass and polydimethylsiloxane (PDMS) are the staple materials for proof-of-concept and prototype chip fabrication, they are not a feasible solution for commercial production due to their slow, labor-intensive production rate. Alternatively, a molded or extruded thermoplastic solution can deliver the precision, consistency, and high volume capability required for commercial scale production. Traditional thermoplastics, such as polymethylmethacrylate (PMMA), polycarbonate (PC), and polystyrene (PS), are well known by development engineers in the bioscience community; however, cyclo-olefin polymer (COP), a relative newcomer in the world of plastics, is gaining increasing attention for use in microfluidic devices due to its unique balance of key properties compared to conventional thermoplastics. In this paper, we provide a comprehensive look at the properties which make COP an excellent candidate for providing the flow cell support and reagent storage functions in microfluidic assays. We also explore the processing attributes and capabilities of COP resin and film which are crucial for manufacturing high-performance microfluidic devices.

In this paper, we report on the formation of micro/nano-fluidic channels inside fused silica glass using single-beam femtosecond laser. The micro/nano-fluidic channels are fabricated by controlling the irradiation conditions of the femtosecond laser pulses, especially, pulse energy and scanning speed. We examine the production of this kind of channels both in air and water. In both cases, laser beam is focused inside the glass bar and shined horizontally with very low scanning speeds. In case of water, the glass sample is placed inside distilled water, which way is expected to reduce the surface roughness of the channels. The quality of the channels fabricated under different environment is compared as well. We further investigate the influence of various laser parameters on the production of channels. We also evaluate the fluid flowing ability of the fabricated micro/nano-fluidic channels of various diameters, fabricated under different environment and irradiation conditions.

Our overall goal is to enable timely diagnosis of infectious diseases through nucleic acid testing at the point-of-care and in low resource settings, via a compact system that integrates nucleic acid sample preparation, isothermal DNA amplification, and nucleic acid lateral flow (NALF) detection. We herein present an interim milestone, the design of the amplification and detection subsystem, and the characterization of thermal and fluidic control and assay execution within this system. Using an earlier prototype of the amplification and detection unit, comprised of a disposable cartridge containing flexible pouches, passive valves, and electrolysis-driven pumps, in conjunction with a small heater, we have demonstrated successful execution of an established and clinically validated isothermal loop-mediated amplification (LAMP) reaction targeting Mycobacterium tuberculosis (M.tb) DNA, coupled to NALF detection. The refined design presented herein incorporates miniaturized and integrated electrolytic pumps, novel passive valves, overall design changes to facilitate integration with an upstream sample preparation unit, and a refined instrument design that automates pumping, heating, and timing. Nucleic acid amplification occurs in a two–layer pouch that facilitates fluid handling and appropriate thermal control. The disposable cartridge is manufactured using low-cost and scalable techniques and forms a closed system to prevent workplace contamination by amplicons. In a parallel effort, we are developing a sample preparation unit based on similar design principles, which performs mechanical lysis of mycobacteria and DNA extraction from liquefied and disinfected sputum. Our next step is to combine sample preparation, amplification, and detection in a final integrated cartridge and device, to enable fully automated sample-in to answer-out diagnosis of active tuberculosis in primary care facilities of low-resource and high-burden countries.

Point-of-care diagnostics (POC) is one of the key application fields for lab-on-a-chip devices. While in recent years much of the work has concentrated on integrating complex molecular diagnostic assays onto a microfluidic device, there is a need to also put comparatively simple immunoassay-type protocols on a microfluidic platform. In this paper, we present the development of a microfluidic cartridge using an immunofiltration approach. In this method, the sandwich immunoassay takes place in a porous frit on which the antibodies have immobilized. The device is designed to be able to handle three samples in parallel and up to four analytical targets per sample. In order to meet the critical cost targets for the diagnostic market, the microfluidic chip has been designed and manufactured using high-volume manufacturing technologies in mind. Validation experiments show comparable sensitivities in comparison with conventional immunofiltration kits.

Gestational diabetes is a global epidemic where many urban areas in Southeast Asia have found prevalence rates as high as 20%, exceeding the highest prevalence rates in the developed world. It can have serious and life-threatening consequences for mothers and babies. We are developing two variants of a new, simple, low-cost rapid test for screening for gestational diabetes mellitus for use primarily in low-resource settings. The pair of assays, both semiquantitative rapid diagnostic strip tests for glycated albumin, require neither fasting nor an oral glucose challenge test. One variant is an extremely simple strip test to estimate the level of total glycated albumin in blood. The other, which is slightly more complex and expensive, is a test that determines the ratio of glycated albumin to total albumin. The screening results can be used to refer women to receive additional care during delivery to avoid birth complications as well as counseling on diet and exercise during and after pregnancy. Results with the latter test may also be used to start treatment with glucose-lowering drugs. Both assays will be read visually. We present initial results of a preliminary cost-performance comparison model evaluating the proposed test versus existing alternatives. We also evaluated user needs and schematic paper microfluidics-based designs aimed at overcoming the challenge of visualizing relatively narrow differences between normal and elevated levels of glycated albumin in blood.

A point-of-care and home-care lab-on-a-chip (LoC) system that integrates a microfluidic spiral device as a concentrator with an optical-coding device as a cell enumerator is demonstrated. The LoC system enumerates white blood cells from dialysis effluent of patients receiving peritoneal dialysis. The preliminary results show that the white blood cell counts from our system agree well with the results from commercial flow cytometers. The LoC system can potentially bring significant benefits to end stage renal disease (ESRD) patients that are on peritoneal dialysis (PD).

Recent advances in materials engineering have enabled photovoltaic (PV) cells to be fabricated from solid state semiconductors, photosensitive organic dyes, and photoactive proteins. One type of organic PV cell is based on the natural light-harvesting protein bacteriorhodopsin (bR) found in the plasma membrane of a salt marsh archaebacteria. When exposed to sunlight, each bR molecule acts as a simple proton pump which transports hydrogen ions from the cytoplasmic to the extracellular side through a transmembrane ion channel. Two types of bR-PV cells comprised of photosensitive dry and aqueous (wet) bR thin films are described in this paper. The self-assembled monolayer of oriented purple membrane (PM) patches from the bR protein is created on a bio-functionalized gold (Au) surface using a biotin molecular recognition technique. The dry bR monolayer is covered with an optically transparent Indium Tin Oxide (ITO) electrode to complete the dry bR-PV device. In contrast, the aqueous bR-PV cell is created by immobilizing the bR monolayer on an Au-coated porous substrate and then inserting the assembly between two micro-reservoirs filled with KCl solutions. Platinum wire probes are then inserted in the opposing liquid reserviors near the porous bR monolayer. The dry bR-PV cell generated a photo-electric response of 9.73 mV/cm², while the aqueous bR-PV produced 41.7 mV/cm² and 33.3 μA/cm². Although the generated voltages appear small, it may be sufficient to power various microelectromechanical systems (MEMS) and microfluidic devices.

Many infectious diseases, as well as some cancers, that affect global health are most accurately diagnosed through nucleic acid amplification and detection. There is a great need to simplify nucleic acid-based assay systems for use in global health in low-resource settings as well as in settings that do not have convenient access to laboratory staff and equipment such as doctors’ offices and home care settings. In developing countries, unreliable electric power, inadequate supply chains, and lack of maintenance for complex diagnostic instruments are all common infrastructure shortfalls. Many elements of instrument-free, disposable, nucleic acid amplification assays have been demonstrated in recent years. However, the problem of instrument-free,1 low-cost, temperature-controlled chemical heating remains unsolved. In this paper we present the current status and results of work towards developing disposable, low-cost, temperature-controlled heaters designed to support isothermal nucleic acid amplification assays that are integrated with a two-dimensional paper network. Our approach utilizes the heat generated through exothermic chemical reactions and controls the heat through use of engineered phase change materials to enable sustained temperatures required for nucleic acid amplification. By selecting appropriate exothermic and phase change materials, temperatures can be controlled over a wide range, suitable for various isothermal amplification methods, and maintained for over an hour at an accuracy of +/- 1°C.

In this study, we developed a microfluidic biochip to perform laser guidance on two cell types, chick embryonic forebrain neurons and chick embryonic spinal cord neurons. The neurons we obtained from these two cell types have no difference in morphology as observed under a high-magnification microscope. However, when flowing in the microfluidic channel and simultaneously being laser-guided, the two cell types gained quite different guidance velocities under the same experimental conditions. The experimental results demonstrate that different cell types with the same morphology (e.g., size, shape, etc.) can be effectively distinguished from each other by measuring the difference of guidance velocities (the maximum flow velocities minus the initial flow velocities). This technique is expected to provide a new approach to high-throughput, label-free cell sorting with sensitivity.

A versatile platform for efficient cell lysis using a combination of acoustic and electric fields in a microchannel is presented. Cell membrane disruption is triggered by electric fields inducing electroporation and then lysis. The principle of optoelectronic tweezers (OET) is applied to control the electric field strength and a surface acoustic wave transducer is attached to an OET chip to implement acoustic tweezing (AT). The system is characterized in terms of spatial control of electric fields, single cell precision and lysis times. Under continuous operation, a combination of AT and OET improves cell lysis significantly achieving for sample concentrations of 10⁶ cell/ml lysis efficiencies of > 99%.

We build a microfluidic trap-based microsphere array device. In the device, we design a novel geometric structure of the trap array and employ the hydrodynamic trapping mechanism to immobilize the microspheres. We develop a comprehensive and robust framework to optimize the values of the geometric parameters to maximize the microsphere arrays’ packing density. We also simultaneously optimize multiple criteria, such as efficiently immobilizing a single microsphere in each trap, effectively eliminating fluidic errors such as channel clogging and multiple microspheres in a single trap, minimizing errors in subsequent imaging experiments, and easily recovering targets. Microsphere-trapping experiments have been performed using the optimized device and a device with un-optimized geometric parameters. These experiments demonstrate easy control of the transportation and manipulation of the microspheres in the optimized device. They also show that the optimized device greatly outperforms the un-optimized one.

Measurement of apoptotic markers in tumors can be directly correlated with the cell cycle phase using flow cytometry (FCM). The conventional DNA content analysis requires cell permeabilization to stain nuclei with fluorescent probes such as propidium iodide or use of a costly UV-excitation line for Hoechst 33342 probe. The access to FCM is also still limited to centralized core facilities due to its inherent high costs and complex operation. This work describes development and proof-of-concept validation of a portable and user-friendly microfluidic flow cytometer (μFCM) that can perform multivariate real time analysis on live cells using sampling volumes as small as 10 microliters. The μFCM system employs disposable microfluidic cartridges fabricated using injection molding in poly(methylmethacrylate) transparent thermoplastic. Furthermore, the dedicated and miniaturized electronic hardware interface enables up to six parameter detection using a combination of spatially separated solid-state 473 (10 mW) and 640 nm (20 mW) lasers and x-y stage for rapid laser alignment adjustment. We provide new evidence that a simple 2D flow focusing on a chip is sufficient to measure cellular DNA content in live tumor cells using a far-red DNA probe DRAQ5. The feasibility of using the μFCM system for a dose-response profiling of investigational anti-cancer agents on human hematopoietic cancer cells is also demonstrated. The data show that μFCM can provide a viable novel alternative to conventional FCM for multiparameter detection of caspase activation and dissipation of mitochondrial inner membrane potential (ΔΨm) in relation to DNA content (cell cycle phase) in live tumor cells.

Lateral flow tests (LFTs) are well-suited for rapid point-of-care testing in low resource settings. The wicking action of the paper strip moves the sample and reagents through the device without a need for pumps, but LFTs are typically limited to tests that can be carried out in a single fluidic step. The materials from LFTs can be reconfigured to create paper networks that automatically carry out multi-step fluidic operations, while retaining the same easy-to-use format as a conventional LFT. Here, we describe basic principles of wicking and system-level behavior of paper networks by analogy to electrical circuits. We describe key design principles for a previously-developed 2D paper network (2DPN) and introduce an alternative linear paper network (Pseudo-1DPN) that takes advantage of system-level behavior to perform clean sequential fluid delivery while reducing device running time.

The development of a paper-based analytical device (PAD) for assessing personal exposure to particulate metals will be presented. Human exposure to metal aerosols, such as those that occur in the mining, construction, and manufacturing industries, has a significant impact on the health of our workforce, costing an estimated $10B in the U.S and causing approximately 425,000 premature deaths world-wide each year. Occupational exposure to particulate metals affects millions of individuals in manufacturing, construction (welding, cutting, blasting), and transportation (combustion, utility maintenance, and repair services) industries. Despite these effects, individual workers are rarely assessed for their exposure to particulate metals, due mainly to the high cost and effort associated with personal exposure measurement. Current exposure assessment methods for particulate metals call for an 8-hour filter sample, after which time, the filter sample is transported to a laboratory and analyzed by inductively-coupled plasma (ICP). The time from sample collection to reporting is typically weeks and costs several hundred dollars per sample. To exacerbate the issue, method detection limits suffer because of sample dilution during digestion. The lack of sensitivity hampers task-based exposure assessment, for which sampling times may be tens of minutes. To address these problems, and as a first step towards using microfluidics for personal exposure assessment, we have developed PADs for measurement of Pb, Cd, Cr, Fe, Ni, and Cu in aerosolized particulate matter.

The conventional approach to measurement of the deflection of microfabricated cantilevers centers on the use of an optical lever. The use of optical lever technology increases the size, complexity, and cost of systems using microfabricated cantilevers. Occasionally, piezoresistors have been used to sense deflection. But, for atomic force microscope applications in particular, topographical sensitivity has demanded the higher sensitivity of the optical lever. For dip-pen nanolithography (DPN) microfabricated cantilevers do not require the same degree of deflection sensitivity. So, for these applications, piezoresistors can be used to sense deflection. In this work, we present a novel approach to an integrated DPN pen. Piezoresistive silicon stress sensors are integrated into a silicon nitride cantilever. The device design, process design, and fabrication methods for building these sensors, and sensor-actuators, are demonstrated. Integration of heaters, along with the piezoresistors, is also demonstrated.

MEMS/MOEMS based systems are increasingly applied in the biological and biomedical context, e.g. in form of biosensors or substrates for monitoring biological responses such as cell migration. For such applications, technical surfaces have to be provided with suitable biochemical functionalization. Typical functionalization procedures include wet-chemical techniques based on self-assembled monolayers of thiols on gold or silanes on glass. These processes create binary patterns and are often of limited use if spatially constrained non-binary patterns like surface bound biochemical gradients have to be provided. In order to create gradients or patterns, methods such as direct spotting or dip pen nanolithography can be used. Here, gradients can be emulated by varying the spot density or the concentration of the solutions employed. However, these methods are serial in nature and are thus of limited use if large surface areas have to be patterned. We present a technique to generate gradients of biochemical function by a photobleaching-based process allowing fast large-scale patterning. The process is based on photobleaching resulting in light-induced coupling of a fluorescently tagged biomolecule to a technical surface by concerted bleaching of the fluorophore. We custom designed a maskless projection lithography system based on a digital mirror device that allows the rapid creation of 8-bit grayscale protein patterns on any technical surface from digital data (e.g. bitmap files). We demonstrate how this process can be used to obtain patterns of several cm² lateral size at micrometer resolution within minutes.

The Gulf of Mexico oil spill is the largest offshore oil spill in U.S. history and great disaster. In situ and real-time monitoring the crude oil concentration is a critical topic after the oil spill. A new generation instrument is reported in this paper which miniaturizes the physical sizes while still maintaining the sensitivity of sensors. The key point is to miniaturize the extraction processing and also to integrate the extraction and detection on the same chip substrate. The sample handling and sensing units will be integrated on the chip itself and can be used as an independent and replaceable detecting head. The fabrication process of the device is introduced. Surface modification need to be done to keep extraction two phases stable. Other parameters of the device are well set. The test experiment result shows that this device can magnitude as high as 7 times concentration after 15 mins extraction.

An all-at-once factorial method is presented, which optimizes protein ink deposition using microfabricated pens by identifying the pen design which writes the greatest number of uniform-size spots or droplets without re-inking. Pen features associated with capillary ink transport are varied according to statistical design-of-experiment (SDOE) principles, and evaluated using a special 1D pen array of twelve pens. Variable parameter pens are bracketed by control pens. Each pen array element embodies one component of the SDOE matrix. All parameters are evaluated simultaneously with a single droplet writing pass. Results can also be evaluated simultaneously, leading to rapid choice of those pen parameters which deliver the greatest number of printed features having the smallest coefficient of variation.

The reagent delivery mechanism in a point-of-care, HIV diagnostic, microfluidic device is studied. Reagents held in an aluminum blister pack are released on the opening of a fluidic seal. The fluidic seals, controlling the flow of reagents, are characterized to reduce anomalies in the desired flow pattern. The findings of this research can be divided into three categories – 1) bonding phenomenon 2) influence of seal pattern on flow and rupture mechanics and 3) process parameters which minimize flow anomalies. Four seal patterns – line hemisphere, line flat, chevron hemisphere and chevron flat were created and tested for reagent delivery using a flow sensor and a force gauge. Experiments suggest that one of the patterns – line-flat – inducted the fewest flow anomalies. A parameter scoping exercise of the seal manufacturing process parameters (temperature, time, pressure) was performed for the line flat seal. Temperature, time, pressure / gap and distance settings which minimize flow anomalies were found.

We developed a monolithic subsystem that integrates a micro-gas chromatography (μGC) separation column and on-column, non-destructive Fabry-Pérot (FP) vapor sensors on a single silicon chip. The device was fabricated using deep reactive ion etching of silicon to create fluidic channels and polymers were deposited on the same silicon chip to act as a stationary phase or an FP sensor, thus avoiding dead volumes caused by the interconnects between the column and sensor traditionally used in μGC. Two integration designs were studied. In the first design, the μGC column was coated with a layer of polymer that served as both the stationary phase and the FP sensor, which has the greatest level of integration. In the second design, a FP sensor array spray-coated with different vapor sensing polymers was integrated with the μGC column, which significantly improves the system flexibility and detection sensitivity. With this design, we show that the FP sensors have a detection limit on the order of tens of picograms with a sub-second response time. Furthermore, FP sensor array are shown to respond to a mixture of analytes separated by the integrated separation channel, allowing for the construction of response patterns, which, along with retention time, can be used as a basis of analyte identification.

Interstitial fluid (ISF) can be transdermally extracted using low-frequency ultrasound and continuous vacuum pressure on skin surface. But the tiny volume of transdermally extracted ISF makes the transdermal extraction, collection, transport, volumetric detection and glucose concentration measurement of the ISF very difficult. Based on a microfluidic chip for transdermally extraction of interstitial fluid and a micro glucose sensor for glucose concentration measurement, a continuous glucose monitoring instrumentby ISF transdermal extraction with minimally invasive way is developed. In the paper, various parts of the device and their interface circuits are designed; the hardware and software of the instrument are built; the simulating experiments of transdermal ISF extraction, collection and volume measurement with full-thickness pig skin are performed using this integrated system; and the functionalities of this device is verified for future clinical application.

Here we present two optofluidic configurations: a spectrometer and a beam aligner. The spectrometer has a compound element that consists of an optofluidic lens and a relief blazed diffraction grating. When light traverses the two optical elements it is focused and diffracted. At the focal length a spectrum is present. This spectrum can be collected by a CCD and information sent to a computer for analysis. Regarding the beam aligner it is made with two hollow prisms oriented 90° to each other. By changing the liquid inside the prisms an X-Y movement can be performed to align the beam.

Transgenic zebrafish (Danio rerio) models of human diseases have recently emerged as innovative experimental systems in drug discovery and molecular pathology. None of the currently available technologies, however, allow for automated immobilization and treatment of large numbers of spatially encoded transgenic embryos during real-time developmental analysis. This work describes the proof-of-concept design and validation of an integrated 3D microfluidic chip-based system fabricated directly in the poly(methyl methacrylate) transparent thermoplastic using infrared laser micromachining. At its core, the device utilizes an array of 3D micro-mechanical traps to actively capture and immobilize single embryos using a low-pressure suction. It also features built-in piezoelectric microdiaphragm pumps, embryo trapping suction manifold, drug delivery manifold and optically transparent indium tin oxide (ITO) heating element to provide optimal temperature during embryo development. Furthermore, we present design of the proof-of-concept off-chip electronic interface equipped with robotic servo actuator driven stage, innovative servomotor-actuated pinch valves and miniaturized fluorescent USB microscope. Our results show that the innovative device has 100% embryo trapping efficiency while supporting normal embryo development for up to 72 hours in a confined microfluidic environment. We also present data that this microfluidic system can be readily applied to kinetic analysis of a panel of investigational anti-angiogenic agents in transgenic zebrafish Tg(fli1a:EGFP) line. The optical transparency and embryo immobilization allow for convenient visualization of developing vasculature patterns in response to drug treatment without the need for specimen re-positioning. The integrated electronic interfaces bring the Lab-on-a-Chip systems a step closer to realization of complete analytical automation.

Sensitive fluorescence sensors are needed to measure single cell properties in microfluidic devices. Optimizing the parallelizability and the measurement volume are two options enabling high throughput applications. The fluorescence sensor presented is highly parallelizable and, due to MEMS micromirror arrays, several sensors can be integrated in one multichannel microfluidic system. The fluorescence sensor has a detection volume of a few thousand femtoliters, covering the full cross-sections of the microfluidic channels used and can be easily adjusted to other cross-section geometries. By measuring labeled particles with diameters below 10 μm we qualified the applicability of the sensor with different channel geometries. The sensors have measurement volumes fitted to the channel geometries with widths from 20 μm up to 400 μm and reach a decision limit of less than 1790 molecules of equivalent soluble fluorophore.

Microsphere arrays can be used to effectively detect, identify, and quantify biological targets, such as mRNAs, proteins, antibodies, and cells. In this work, we design a microfluidic microsphere-trap array device that enables simultaneous, efficient, and accurate screening of multiple targets on a single platform. Different types of targets are captured on the surfaces of microspheres of different sizes. By optimizing the geometric parameters of the traps, the trap arrays in this device can immobilize microspheres of different sizes at different regions with microfluidic hydrodynamic trapping. The targets are thus detected according to the microspheres’ positions (position-encoding), which simplifies screening and avoids errors in target identification. We validate the design using fluid dynamics finite element simulations by COMSOL Multiphysics software using microsphere of two different sizes. We also performed preliminary microspheretrapping experiments on a fabricated device using microspheres of one size. Our results demonstrate that the proposed device can achieve the position-encoding of the microspheres with few fluidic errors. This device is promising for simultaneous detection of multiple targets and become a cheap and fast disease diagnostic tool.