This PDF file contains the front matter associated with SPIE Proceedings Volume 10491 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

A silicon microneedle array with integrated microfluidic channels is presented, which is designed to extract dermal interstitial fluid (ISF) for biochemical analysis. ISF is a cell-free biofluid that is known to contain many of the same constituents as blood plasma, but the scope and dynamics of biomarker similarities are known for only a few components, most notably glucose. Dermal ISF is accessible just below the outer skin layer (epidermis), which can be reached and extracted with minimal sensation and tissue trauma by using a microneedle array. The microneedle arrays presented here are being developed to extract dermal ISF for off-chip profiling of nucleic acid constituents in order to identify potential biomarkers of disease. In order to assess sample volume requirements, preliminary RNA profiling was performed with suction blister ISF. The microneedles are batch fabricated using established silicon technology (low cost), are small in size, and can be integrated with sensors for on-chip analysis. This approach portends a more rapid, less expensive, self-administered assessment of human health than is currently achievable with blood sampling, especially in non-clinical and austere settings. Ultimately, a wearable device for monitoring a person’s health in any setting is envisioned.

Previous studies have demonstrated that flow-induced shear stress induces a motile and aggressive tumor phenotype in a microfluidic model of 3D ovarian cancer. However, the magnitude and distribution of the hydrodynamic forces that influence this biological modulation on the 3D cancer nodules are not known. We have developed a series of numerical and experimental tools to identify these forces within a 3D microchannel. In this work, we used particle image velocimetry (PIV) to find the velocity profile using fluorescent micro-spheres as surrogates and nano-particles as tracers, from which hydrodynamic forces can be derived. The fluid velocity is obtained by imaging the trajectory of a range of florescence nano-particles (500–800 μm) via confocal microscopy. Imaging was done at different horizontal planes and with a 50 μm bead as the surrogate. For an inlet current rate of 2 μl/s, the maximum velocity at the center of the channel was 51 μm/s. The velocity profile around the sphere was symmetric which is expected since the flow is dominated by viscous forces as opposed to inertial forces. The confocal PIV was successfully employed in finding the velocity profile in a microchannel with a nodule surrogate; therefore, it seems feasible to use PIV to investigate the hydrodynamic forces around 3D biological models.

The conversion of light energy into mechanical energy for directed photoactuation is a goal that has been pursued for decades. This work has led to azobenzene liquid-crystal polymers (LCPs), which demonstrate photo-activated bending when irradiated with UV or blue-green light. This intriguing phenomenon has potential to significantly impact the fields of Lab-on-a-Chip, MEMS and soft robotics, but the jump into practical application requires precise fabrication of azobenzene-based structures capable of being leveraged into useful and efficient photomechanical work. Three such configurations have been designed to this end: azobenzene films patterned by soft lithography, azobenzene nanofibers and azobenzene nanobeads.

Paper-based microfluidic devices offer great potential as a low-cost platform to perform chemical and biochemical tests. Commercially available formats such as dipsticks and lateral-flow test devices are widely popular as they are easy to handle and produce fast and unambiguous results. While these simple devices lack precise control over the flow to enable integration of complex functionality for multi-step processes or the ability to multiplex several tests, intense research in this area is rapidly expanding the possibilities. Modeling and simulation is increasingly more instrumental in gaining insight into the underlying physics driving the processes inside the channels, however simulation of flow in paper-based microfluidic devices has barely been explored to aid in the optimum design and prototyping of these devices for precise control of the flow. In this paper, we implement a multiphase fluid flow model through porous media for the simulation of paper imbibition of an incompressible, Newtonian fluid such as when water, urine or serum is employed. The formulation incorporates mass and momentum conservation equations under Stokes flow conditions and results in two coupled Darcy’s law equations for the pressures and saturations of the wetting and non-wetting phases, further simplified to the Richard’s equation for the saturation of the wetting fluid, which is then solved using a Finite Element solver. The model tracks the wetting fluid front as it displaces the non-wetting fluid by computing the time-dependent saturation of the wetting fluid. We apply this to the study of liquid transport in two-dimensional paper networks and validate against experimental data concerning the wetting dynamics of paper layouts of varying geometries.

In the early years and still very much to date, optical detection technologies, namely fluorescence-based methods, have been the predominant detection technology for most microfluidic application cases as they reach very high sensitivity down to single molecules. For point-of-need applications however, e.g. in point-of-care diagnostics, a significant trend towards alternative detection methods can be observed. Driver behind this development is the desire for label-free and more robust methods, ideally coupled with reduced complexity requirements for the associated instrument. Sensors can be one way to achieve these goals and especially silicon photonic sensors show a great potential to combine sensitive detection with low read-out complexity. Such silicon-based devices however have to be integrated into a microfluidic cartridge which performs all other assay steps, namely sample preparation and fluid manipulation. This heterogeneous integration poses a significant challenge in manufacturing. In this paper we describe different strategies and adhesive as well as non-adhesion bonding technologies and an outline of the development process of design rules for silicon photonic sensors with respect to microfluidic cartridge integration. These design rules are necessary as they are independent from the photonic and silicon process design rules but have similar impact on the device layout.

Point-of-care (POC) testing attracts more and more attention in the medical health sector because of their specific property to perform the diagnostic close to the patient. The fast diagnosis right at the hospital or the doctor’s office improves the medical reaction time and the chances for a successful healing process. One of this POC test systems is a “Lab-on-a-Disc” (LoaD) which looks like a compact disc crisscrossed with microfluidic tubes and cavities. The fluid to be analysed is placed in the LoaD and an external device then rotates the LoaD. The cavities inside the LoaD and the centrifugal force ensure a clearly defined sequence of the analysis. Furthermore, we aim for an inexpensive manufacture of the medical product without neglecting its quality and functionality. Therefore, the Fraunhofer IPT works on an assembly cell to implement dissoluble films concisely into the disc. This dissoluble film demonstrates its successful usage as a gate for the fluid, which opens after a predefined moment in the cycle. Furthermore, we investigate to integrate a laser welding process into our gantry system and demonstrate its efficiency with the welding of polymer discs. This procedure is clinically safe because no further laser absorption material is needed in the sealing process, which might pollute the LoaD. Moreover, this process allows the alignment of several discs before the welding and therefore leads to precisely manufactured LoaDs in large quantities. All these methods together enable a fast, costefficient and reliable mass production to bring POC testing among the people.

Additive manufacturing has gained great interest in the microfluidic community due to the numerous channel designs which can be tested in the early phases of a lab-on-a-chip device development. High resolution additive manufacturing like microstereolithography is largely associated with polymers. Polymers are at a disadvantage compared to other materials due to their softness and low chemical resistance. Whenever high chemical and thermal resistance combined with high optical transparency is needed, glasses become the material of choice. However, glasses are difficult to structure at the microscale requiring hazardous chemicals for etching processes. In this work we present additive manufacturing and high resolution patterning of microfluidic chips in transparent fused silica glass using stereolithography and microlithography. We print an amorphous silica nanocomposite at room temperature using benchtop stereolithography printers and a custom built microlithography system based on a digital mirror device. Using microlithography we printed structures with tens of micron resolution. The printed part is then converted to a transparent fused silica glass using thermal debinding and sintering. Printing of a microfluidic chip can be done within 30 minutes. The heat treatment can be done within two days.

3D printing hydrogels via stereolithography is a promising system for the creation of regenerative medical implants. However, the mechanical and chemical properties of materials patterned using stereolithography-based printing techniques are largely unknown. In an effort to understand how optical propagation, polymerization, and transport dynamics result in material mechanical property distribution, this study focuses on the axial (depth) characterization of single-layer printed materials as a function of light intensity, exposure time and absorption depth. We use a poly(ethylene glycol) diacrylate based photopolymerization chain-growth reaction with an approximate bulk modulus of 39 MPa to explore this phenomenon. Fourier transform infrared spectroscopy (FTIR) is employed to quantify the degree of monomer conversion over time and intensity, while comparing it with a Beer-Lambert model that describes the effect of Tinuvin CarboProtect, the neutral absorber in our material on conversion as a function of depth. To evaluate the mechanical properties of the printed materials, compression testing is performed on each sample to extract the bulk modulus and to map conversion as a function of exposure time by fitting the force-displacement curves of each condition to the Hertz model for a quantitative comparison of material stiffness. This study aims to understand material and mechanical property distribution in a single layer, and use this understanding to create a predictive model of these properties, as well as decrease the scale of the distribution with the implementation of a novel post-cure technique. This work enables predictive models of microscopic polymer properties that can be translated into improved macroscopic structural properties to form a robust polymer network for tissue engineering microstructures.

Cavity optomechanics have become a promising route towards the development of ultrasensitive sensors for a wide range of applications including mass, chemical and biological sensing. In this study, we demonstrate the potential of Very Large Scale Integration (VLSI) with state-of-the-art low-loss performance silicon optomechanical microdisks for sensing applications. We report microdisks exhibiting optical Whispering Gallery Modes (WGM) with 1 million quality factors, yielding high displacement sensitivity and strong coupling between optical WGMs and in-plane mechanical Radial Breathing Modes (RBM). Such high-Q microdisks with mechanical resonance frequencies in the 10² MHz range were fabricated on 200 mm wafers with Variable Shape Electron Beam lithography. Benefiting from ultrasensitive readout, their Brownian motion could be resolved with good Signal-to-Noise ratio at ambient pressure, as well as in liquid, despite high frequency operation and large fluidic damping: the mechanical quality factor reduced from few 10³ in air to 10’s in liquid, and the mechanical resonance frequency shifted down by a few percent. Proceeding one step further, we performed an all-optical operation of the resonators in air using a pump-probe scheme. Our results show our VLSI process is a viable approach for the next generation of sensors operating in vacuum, gas or liquid phase.

A main step for the development and the validation of medical drugs is the screening on whole organisms, which gives the systemic information that is missing when using cellular models. Among the organisms of choice, Caenorhabditis elegansis a soil worm which catches the interest of researchers who study systemic physiopathology (e.g. metabolic and neurodegenerative diseases) because: (1) its large genetic homology with humans supports translational analysis; (2) worms are much easier to handle and grow in large amounts compared to rodents, for which (3) the costs and (4) the ethical concerns are substantial.C. elegansis therefore well suited for large screens, dose-response analysis and target-discovery involving an entire organism. We have developed and tested a microfluidic array for high-content screening, enabling the selection of small populations of its first larval stage in many separated chambers divided into channels for multiplexed screens. With automated protocols for feeding, drug administration and image acquisition, our chip enables the study of the nematodes throughout their entire lifespan. By using a paralyzing agent and a mitochondrial-stress inducer as case studies, we have demonstrated large field-of-view motility analysis, and worm-segmentation/signal-detection for mode-of-action quantification with genetically-encoded fluorescence reporters.

The escalating research interests in porous media microfluidics, such as microfluidic paper-based analytical devices (μPADs), have fostered a new spectrum of microfluidic devices for point-of-care diagnosis and biosensing. In this paper, we report diatomite microfluidic devices, which consist of multi-scale hierarchically porous photonic crystal biosilica channels, as an innovative lab-on-a-chip platform to detect hazardous chemicals. The diatomite microfluidic devices in this work are fabricated by simple spin-coating and tape-stripping diatomaceous earth on regular glass slides with cross section of 400×30μm2. As the most unique feature, our diatomite microfluidic devices can simultaneously perform on-chip chromatography to separate small molecules from complex samples and acquire the surface-enhanced Raman scattering spectra of the target chemicals with high specificity. Owing to the ultra-small dimension of the diatomite microfluidic channels and the photonic crystal effect from the fossilized diatom frustules, we demonstrate unprecedented sensitivity down to ppb-level when detecting pyrene (1ppb) from mixed sample with Raman dye and cocaine (10ppb) from human plasma. This pioneering work proves the exclusive advantage of diatomite microfluidic devices as emerging microfluidic devices for chemical and biomedical sensing.

The development of organ-on-chip and biological scaffolds is currently requiring simpler methods to microstructure biocompatible materials in three dimensions, fabricate structural and functional elements in biomaterials or modify the physicochemical properties of desired substrates. With the aim of creating simple, cost-effective alternatives to conventional existing techniques to produce such platforms with very specific properties, a low-power CD-DVD laser pickup head was recycled and mounted on a programmable three-axis micro-displacement system in order to modify the surface of polymeric materials in a local fashion. Thanks to a specially-designed method using a strongly absorbing additive coating the materials of interest, it has been possible to establish and precisely control processes useful in microtechnology for biomedical applications and normally restricted to much less affordable high-power lasers. In this work, we present our latest progress regarding the application of our fabrication technique to the development of organ-on-chip platforms thanks to the simple integration of several biomimetic characteristics typically achieved with traditional, less cost-effective microtechnology methods in one step or through replica-molding. Our straightforward approach indeed enables great control of local laser microablation for true on-demand biomimetic micropatterned designs in several transparent polymers and hydrogels of tunable stiffness and is allowing integration of microfluidics, microelectronics, optical waveguides, surface microstructuring and even transfer of superficial protein micropatterns on a variety of biocompatible materials. The results presented here were validated using hepatic and fibroblasts cell lines to demonstrate the viability of our procedure for organ-on-chip development and show the impact of such features in cell culture.

Aqueous two-phase systems (ATPSs) form from the thermodynamic separation of two dissolved incompatible solutes, such as two polymers, a polymer and a salt, and a polymer and a surfactant. At most supercritical concentrations, ATPS emulsions can be formed by vigorous mixing. These emulsions typically settle into distinct layers in minutes to hours. However, it is also possible to choose ATPS compositions with extremely long settling times that resemble stable emulsions. Here, we generated stable emulsions from a polyethylene glycol (PEG)-dextran ATPS by selecting ATPS compositions at the extreme ends of the tie lines connecting the binodal curve delineating phase-separating compositions. Droplets of PEG in a continuous dextran phase did not coalesce appreciably over the course of several days when stored in a conical tube or syringe. However, upon exposure to laminar flow conditions in a microfluidic channel, droplets were observed to coalesce. Through microscopic characterization of droplet volume, an increase in droplet size and decrease in overall droplet number was observed as a function of channel distance, suggesting a progressive droplet merging phenomenon. This novel approach to control droplet size by encouraging coalescence of stable emulsions under laminar flow in a microfluidic channel enables the production of droplets ranging from fL to several pL, which may enable various future biotechnology applications.

Hydrophobic barriers are one of the key elements of microfluidic paper based analytical devices (μPADs).μPADs are simple and cost efficient and they can be carried out without the need of high standard laboratories. To carry out such a test a method is needed to create stable hydrophobic barriers. Commonly used methods like printing wax or polystyrene have the major drawback that these barriers are stiff and break if bended which means they will no longer be able to retain a liquid sample. Here we present silanes to structure hydrophobic barriers via polycondensation and show a silanization method which combines the advantages of flexible silane/siloxane layers with the short processing times of UV-light based structuring. The barriers are created by using methoxy silanes which are mixed with a photo acid generator (PAG) as photoinitiator. Also a photosensitizer was given to the mixture to increase the effectiveness of the PAG. After the PAG is activated by UV-light the silane is hydrolyzed and coupled to the cellulose via polycondensation. The created hydrophobic barriers are highly stable and do not break if being bended.

Polydimethylsiloxane (PDMS) is one of the most widely used polymers for the generation of microfluidic chips. The standard procedures of soft lithography require the formation of a new master structure for every design which is timeconsuming and expensive. All channel generated by soft lithography need to be consecutively sealed by bonding which is a process that can proof to be hard to control. Channel cross-sections are largely restricted to squares or flat-topped designs and the generation of truly three-dimensional designs is not straightforward. Here we present Suspended Liquid Subtractive Lithography (SLSL) a method for generating microfluidic channels of nearly arbitrary three-dimensional structures in PDMS that do not require master formation or bonding and give circular channel cross sections which are especially interesting for mimicking in vivo environments. In SLSL, an immiscible liquid is introduced into the uncured PDMS by a capillary mounted on a 3D printer head. The liquid forms continuous “threads” inside the matrix thus creating void suspended channel structures.

Remotely-controlled robotic air and ground vehicles (frequently collectively called drones) play a rapidly increasing role not only in military operations but for many civilian tasks ranging from traffic surveillance to disaster monitoring. The possibility to do remote sampling in areas otherwise difficult to reach as well as their low acquisition and operating cost compared to other technical solutions make them attractive platforms for chemical and biological analysis systems. The restrictions on size and weight on these platforms together with the need for a rugged system layout makes lab-on-a-chip technologies the prime candidates to be implemented on such a drone platform. We report on a lab-on-a-chip system for such tasks which consist out of a fully integrated lab-on-a-chip cartridge and the respective control hardware. The cartridge contains all reagents in liquid and dry form required to perform a molecular biology assay to identify bacterial pathogens such as Brucella and Francisella. These zoonotic bacteria are classified as biological agents and cause the (re-)emerging diseases brucellosis and tularemia, which occur also in developed countries in a relevant number of human clinical cases. After proof-of-concept for these pathogens, it is planned to expand the platform to further B-agents.

We employ attenuated total reflection (ATR) mid-IR technology for sensing of bacteria present in aqueous solution. In ATR spectroscopy, the penetration depth of the evanescent field extends to approx. 1-2 micrometers into the aqueous solution depending on the refractive index of the employed materials (Si, ZnS, Ge) used as attenuated total reflection (ATR) element and the geometry of the optical set-up. Due to the flow profile in the microfluidic cell, an additional force is required to bring particles into the evanescent field for measurement. For that purpose, we employ standing ultrasound waves produced between a sound source vibrating at approx. 2 MHz and the ATR crystal acting as a reflector. This ultrasonic trap is integrated into the microfluidic channel. As aqueous solution is passing through that acoustofluidic cell, particles are concentrated in the nodal plane of the standing ultrasound wave, forming particle conglomerates. By selecting appropriate experimental conditions, it is then possible to press bacteria against the crystal surface for interaction with the evanescent wave (as well as to keep them away from the ATR element). Our current work aims at establishing a custommade US-ATR-IR setup for signal enhancement of bacteria (e.g. E. coli, P. aeruginosa as well as Salmonella) in drinking water.

A predominant unsolved challenge in tissue engineering is the need of a robust technique for producing vascular networks, particularly when modeling human brain tissue. The availability of reliable in vitro human brain microvasculature models would advance our understanding of its function and would provide a platform for highthroughput drug screening. Current strategies for modeling vascularized brain tissue suffer from limitations such as (1) culturing non-human cell lines, (2) limited multi-cell co-culture, and (3) the effects of neighboring physiologically unrealistic rigid polymeric surfaces, such as solid membranes. We demonstrate a new micro-engineered platform that can address these shortcomings. Specifically, we have designed and prototyped a molding system to enable the precise casting of ~100μm-diameter coaxial hydrogel structures laden with the requisite cells to mimic a vascular lumen. Here we demonstrate that a fine wire with diameter ~130 μm or a needle with outer diameter ~300 μm can be used as a temporary mold insert, and agarose–collagen composite matrix can be cast around these inserts and thermally gelled. When the wire or needle is retracted under the precise positional control afforded by our system, a microchannel is formed which is then seeded with human microvascular endothelial cells. After seven days of culture these cells produce an apparently confluent monolayer on the channel walls. In principle, this platform could be used to create multilayered cellular structures. By arranging a fine wire and a hollow needle coaxially, three distinct zones could be defined in the model: first, the bulk gel surrounding the needle; then, after needle retraction, a cylindrical shell of matrix; and finally, after retraction of the wire, a lumen. Each zone could be independently cell-seeded. To this end, we have also successfully 3D cultured human astrocytes and SY5Y glial cells in our agarose–collagen matrix. Our approach ultimately promises scalable and repeatable production of vascular structures with physiologically realistic mechanical properties.

We present a novel method that allows establishing desired flow patterns in a Hele-Shaw cell, solely by controlling the surface chemistry, without the use of physical walls. Using weak electrolytes, we locally pattern the chamber's ceiling and/or floor, thus defining a spatial distribution of surface charge. This translates to a non-uniform electric double layer which when subjected to an external electric field applied along the chamber, gives rise to non-uniform electroosmotic flow (EOF). We present the theory that allows prediction and design of such flows fields, as well as experimental demonstrations opening the door to configurable microfluidic devices.

The no-slip boundary condition is a signature characteristic of laminar flow, and the Tesla turbine leverages this condition to transfer mechanical rotation into fluidic pressure. This means that the Tesla turbine is optimally driven by microfluidic flow, which maximizes the use of the boundary layer flow. To this end, we employed a lithography based high resolution 3D printing to realize an embedded micro Tesla pump smaller than the diameter of a penny, integrated to a microfluidic network. The pump was completely sealed in the PDMS (polydimethylsiloxane) device and coupled magnetically to a 3” portable stir plate for rotation. The pump was operated up to 4k rpm (verified with an optical tachometer and slow motion capturing), netting an output pressure of 125 Pa. The pressure transients over time was deconvolved with the rotor transients from the stir plate to yield a pump response function, with a decay constant around 1 second. This means that the pump was able to respond to transients as short as 1 second, and negligible shearing did not affect the rotor-stir plate coupling to ensure efficient pumping. Finally, the pump was applied to drive blue and red dyes into a microfluidic mixer network, demonstrating stable, on-chip fluidic flows without external pumps. The transient characterization of the µTesla pump can provide important insights to the scaling of Tesla pumps and the power transfer between mechanical rotation and fluidic flow, leading to better understanding of the Tesla turbine efficiencies.

The digital microfluidics utilizes the gradient in wettability for droplet transportation. This paper reports a novel technique of LED induced wetting ( Opto-wetting) where a single low power LED (Light emitting diode) emitting light of wavelength 395nm peak with luminous intensity of 300mcd (milli candela) is used to move two droplets of 20μL each on a photo responsive substrate of azobenzene (C₁₂H₁₀N₂) coated PDMS (Poly Dimethyl Siloxane) substrate. The PDMS substrate of size 5cmx2cmx0.5cm were modified by thin film coating of Azobenzene dissolved in olive oil solution. The LED was aligned vertically on the top of the substrate. The pulsed operation of LED induces a spatial gradient of surface energy due to the reversible process of photo isomerization of Azobenzene molecules coated on the surface. The Photo-isomerization changes the conformation of the molecules thereby changing its surface energy .The change in surface energy of the substrate induces a change in contact angle of the droplet which initiates its movement. Two water droplets each of 20μL were dispensed on the substrate using micro syringe. Two droplets which were initially at a few cm distance apart were gradually moved towards the focus of light and merged together. The urine droplets (20μL) were moved and mixed with the red dye reagent (20μL) by controlling the light intensity of the LED. This concept provides a cost effective technique of droplet manipulation in the Lab on a chip domain where various multiplexed operations on proteins and DNA droplets can be done for point of care diagnostics.

Cantilever and membrane based sensors, which are capable of providing accurate detection of target analytes have been always an important research topic of medical diagnostics, food testing, and environmental monitoring fields. Here, the mechanical detection is achieved by micro- and nano-scale cantilevers for stress sensing and mass sensing, or micro- and nano-scale plates or membranes. High sensitivity is a major issue for the active element and it could be achieved via increased Q-factor. The ability to control the Q factor expands the range of application of the device and allows to achieve more accurate results. The aim of this paper is to investigate the mechanical and electrical properties, as well as, the ability to control the Q factor of the membrane with PZT nanocomposite. This multilayered membrane was formatted using the n-type <100> silicon substrate by implementing the Low Pressure Chemical Vapor Deposition (LPCVD), photolithography by using photomask with defined dimensions, deep etching, and e-beam evaporation techniques. Dynamic and electrical characteristics of the membrane were numerically investigated using COMSOL Multiphysics software. The use of the multilayered membrane can range from simple monitoring of particles concentration in a closed environment to inspecting glucose levels in human fluids (blood, tears, sweat, etc.).

Measurement of composition of mixtures at high pressures is important in many applications such as supercritical drying of aerogels, high-pressure sterilization and synthesis of nanostructured materials. The frequency response of uncoated microcantilevers immersed in ethanol-CO2 mixtures with compositions ranging from 0.85 to 4 weight % of ethanol in ethanol-CO2 were measured at a temperature of 318 K and pressure range of 10 MPa to 22 MPa. The resonant frequencies and Q-factors were found to decrease with the increasing weight % of ethanol in the mixture. The data indicate that the composition of a mixture can be measured by measuring the resonant frequency of the cantilever in the mixture after obtaining a calibration curve by measuring resonant frequencies of mixtures with known composition. The sensitivity of the technique which is defined as the ratio of resonant frequency shift to the change in fluid mixture was investigated. An analytical expression for sensitivity was derived using Sader’s model. The sensitivity was found to be a complex function of density and viscosity of the mixture as well as the length, density and width of the cantilever. Using the density and viscosity data in the literature for ethanol-CO2 mixtures with various compositions, the sensitivity of the cantilevers were calculated at each pressure and temperature. The results indicate that the minimum composition that can be measured with the current setup is between 480 ppm and 980 in the pressure range of 10 MPa to 22 MPa by using a 150 µm long cantilever and between 600 and 1450 ppm by using 200 µm long cantilever. Acknowledgment: - This project has received funding from the European Union´s Horizon 2020 research and innovation programme under grant agreement No 685648.

Design of inexpensive and portable hand-held microfluidic flow/image cytometry devices for initial medical diagnostics at the point of initial patient contact by emergency medical personnel in the field requires careful design in terms of power/weight requirements to allow for realistic portability as a hand-held, point-of-care medical diagnostics device. True portability also requires small micro-pumps for high-throughput capability. Weight/power requirements dictate use of super-bright LEDs and very small silicon photodiodes or nanophotonic sensors that can be powered by batteries. Signal-to-noise characteristics can be greatly improved by appropriately pulsing the LED excitation sources and sampling and subtracting noise in between excitation pulses. The requirements for basic computing, imaging, GPS and basic telecommunications can be simultaneously met by use of smartphone technologies, which become part of the overall device. Software for a user-interface system, limited real-time computing, real-time imaging, and offline data analysis can be accomplished through multi-platform software development systems that are well-suited to a variety of currently available cellphone technologies which already contain all of these capabilities.

Microfluidic cytometry requires judicious use of small sample volumes and appropriate statistical sampling by microfluidic cytometry or imaging for adequate statistical significance to permit real-time (typically < 15 minutes) medical decisions for patients at the physician’s office or real-time decision making in the field. One or two drops of blood obtained by pin-prick should be able to provide statistically meaningful results for use in making real-time medical decisions without the need for blood fractionation, which is not realistic in the field.

Extracellular vesicles (EVs) have been gaining increasing attention given their role in communicating information between cells. Composition-based isolation of EVs is particularly of high significance as the proteomic and lipidomic characterization of their cargo could provide valuable clues to the role of EVs in mediating the biology of various conditions. This has, however, proved to be challenging as EVs, despite their abundance, are very small and difficult to be differentiated from the other constituents of host media. In addition, currently available methods like ultracentrifugation and filtration are cumbersome and capable of achieving mostly size-based separations. In this work, we demonstrate the possibility of separating submicron EV-like vesicles from cancer cells using a thermally-assisted acoustophoretic device. In a system composed of MCF-7 breast cancer cells spiked with two different types of same-size vesicles, composition-based isolation of vesicles was shown to be realizable through opposite focusing of the system’s components at the node and antinodes of the overlaid ultrasonic standing wave. By proper choice of temperature in the microchannel, we were able to achieve separations with purities exceeding 93%. Furthermore, cells recovered from the channel were shown to be viable after the separation.

Food allergy is a common disease worldwide with over 6% of the population (200-250 million people) suffering from any food allergy nowadays. The most dramatic increase seems to be happening in children and young people. Therefore, improvement in the diagnosis efficiency of these diseases are needed. Immunoglobulin type E (IgE) biomarker determination in human serum is a typical in vitro test for allergy identification. In this work we used a novel biosensor based on label-free photonic transducers called BICELLs (Biophotonic Sensing Cells) for IgE detection. These BICELLs have a thin film of nitrocellulose over the sensing surface, they can be vertical optically interrogated and are suitable for being integrated on-a-chip. The BICELLs sizes used were 100 and 800 µm of diameter. Calibration curves were obtained with IgE standards, by immobilizating anti-IgE antibodies and recognizing with standard IgE calibrators. The results, in similar assay format, were compared with commercial-available ImmunoCAP. The versatility of the interferometric nitrocellulose-based sensing surface was demonstrated since the limit of detections for BICELLs and ImmunoCAP were 0.7 and 0.35 kU/L, respectively.

Hepatocellular carcinoma is one of the most common types of liver cancer causing death all over the world. Although early-stage liver cancer can sometimes be treated with partial hepatectomy, liver transplantation, ablation, and embolization, sorafenib treatment is the only approved systemic therapy for advanced HCC. The aim of this research is to develop tools and methods to understand the individuality of hepatocellular carcinoma. Microfluidic cell-culture platform has been developed to observe behavior of single-cells; fluorescence microscopy has been implemented to investigate phenotypic changes of cells. Our preliminary data proved high-level heterogeneity of hepatocellular carcinoma while verifying limited growth of liver cancer cell lines on the silicon wafer.

DNA origami nanostructures allow for the precise placement of functional entities such as fluorescent dyes, metal nanoparticles and receptor molecules such as DNA aptamers. This makes them an ideal platform to create novel fluorescence and Raman based chemo- and biosensors. Compared to other fluorescent labels functionalized DNA origami nanostructures can be brighter and thus more sensitive than other fluorescent labels and they possess a well-defined number of fluorescent dyes with well-defined inter-dye distance. In this way optimized light-harvesting multichromophore labels can be prepared,[1] which allows for the generation of self-referenced sensors based on Förster resonance energy transfer (FRET).[2] By attaching gold or silver nanoparticles to the DNA origami nanostructures a direct chemical information of analytes can be obtained by surface-enhanced Raman scattering (SERS).[3] Intense SERS hot spots can be formed by creating nanoparticle dimers [3] or trimers [4] (nanolenses) with well-defined inter-particle gap. In addition to the precise arrangement of nanoparticles the DNA origami nanostructures also allow for a specific binding of analyte molecules exactly in the SERS hot spots. In this presentation the detection of micro-RNA, ions and proteins using DNA origami nanostructures by fluorescence and SERS spectroscopy, respectively, will be demonstrated as a proof-of-principle. [1] L. Olejko, I. Bald, RSC Adv. 2017, 7, 23924 [2] L. Olejko, P. Cywinski, I. Bald, Angew. Chem. 2015, 127, 683. [3] J. Prinz et al., Nanoscale 2016, 8, 5612. [4] C. Heck et al., ACS Photonics 2017, 4, 1123.

Immunohistochemistry (IHC) is one of the main techniques currently used in the clinics for biomarker characterization. It consists in colorimetric labeling with specific antibodies followed by microscopy analysis. The results are then used for diagnosis and therapeutic targeting. Well-known drawbacks of such protocols are their limited accuracy and precision, which prevent the clinicians from having quantitative and robust IHC results. With our work, we combined rapid microfluidic immunofluorescent staining with efficient image-based cell segmentation and signal quantification to increase the robustness of both experimental and analytical protocols. The experimental protocol is very simple and based on fast-fluidic-exchange in a microfluidic chamber created on top of the formalin-fixed-paraffin-embedded (FFPE) slide by clamping it a silicon chip with a polydimethyl siloxane (PDMS) sealing ring. The image-processing protocol is based on enhancement and subsequent thresholding of the local contrast of the obtained fluorescence image. As a case study, given that the human epidermal growth factor receptor 2 (HER2) protein is often used as a biomarker for breast cancer, we applied our method to HER2+ and HER2− cell lines. We report very fast (5 minutes) immunofluorescence staining of both HER2 and cytokeratin (a marker used to define the tumor region) on FFPE slides. The image-processing program can segment cells correctly and give a cell-based quantitative immunofluorescent signal. With this method, we found a reproducible well-defined separation for the HER2-to-cytokeratin ratio for positive and negative control samples.

We propose an on-chip photonic particle sensor design that can perform particle sizing and counting for various environmental applications. The sensor is based on micro photonic ring resonators that are able to detect the presence of the free space particles through the interaction with their evanescent electric field tail. The sensor can characterize a wide range of the particle size ranging from a few nano meters to micron (~1 micron). The photonic platform offers high sensitivity, compactness, fast response of the device. Further, FDTD simulations are performed to analyze different particle-light interactions. Such a compact and portable platform, packaged with integrated photonic circuit provides a useful sensing modality in space shuttle and environmental applications.

The rapid growth of point-of-care tests demands for biomolecule sensors with higher sensitivity and smaller size. We developed an optofluidic metasurface that combined silicon photonics and nanofluidics to achieve a lateral flow-through biosensor to fulfill the needs. The metasurface consists of a 2D array of silicon nanoposts fabricated on a silicon-on-insulator substrate. The device takes advantage of the high-Q resonant modes associated with the optical bound state and the nanofluidic delivery of analyte to overcome the problem of diffusion-limited detection that occurs in almost all conventional biosensors and offer a high refractive index sensitivity. We used rigorous coupled wave analysis and finite element analysis to design and optimize the device. We will present its photonic band diagram to identify the optical bound state and high-Q resonance modes near 1550 nm. The device was fabricated using e-beam lithography followed by a lift-off and reactive ion etching process. Reflectance of the sensor was measured using a tunable laser and a photodetector. The preliminary result shows a refractive index sensitivity of 720 nm/RIU. Furthermore, we implemented the optical metasurface as a lateral flow-through biosensor by covering the nanoposts using a PDMS cover. The nanofluidic channels are formed between the nanoposts for the flow of samples. The lateral flow-through sensor was used to detect the epidermal growth factor receptor (ErbB2), a widely used protein biomarker for breast cancer screening. The results show that the device can quantitatively measure the binding of ErBb2 antibody and ErBb2 by the continuous monitoring of the resonant wavelength shift.

Microplastics are small plastic particles contained in cosmetics or caused by abrasion and decomposition of plastic waste in the environment. The increasing pollution by plastic particles and fibers in the size of less than 5 millimeters is great challenge for environmental management. The uptake of microplastics by living organisms may cause mechanical injuries of the gastrointestinal tract and triggers inflammation. The adsorption of pollutants to the particle surface still increases the potential hazard of the particles. Therefore, there is an urgent need for methods to identify microplastics in the environment, its sources of input and, of course, the risk of microplastic particles. The here presented research project MicroPlastiCarrier will develop efficient device concepts for the optical detection and identification of microplastic particles and bacteria in wastewater. The state of the art method is the filtration of liquids and the subsequent detection of microplastic particles with FT-IR. The project aims to overcome the limitations of this technique by the safe identification of microplastics up to a size of up to 250 micrometers in liquid media. This is achieved by a novel combination of optical spectroscopy using infrared light, quantitative phase contrast imaging and Flow Cytometry This principle analyses particles and bacteria in different detection channels because of their size and their absorption and refraction index properties at several wavelengths of light. Combined with innovative microfluidics and laser technology, the device prospects to achieve a significantly higher number of measurements and a speed advantage compared to currently used, labor-intensive filtration processes.

HIL sensor is used to measure Hemoglobin (Hb), Icterus and Lipemia in plasma. Conventionally, HIL is detected in centrifuged plasma sample using a spectrophotometer. Such centrifuged sample provides uniform sample without impurity and it is possible to use longer optical path lengths in the range of millimeter. In such situations, a spectrophotometer is sufficient to provide signal to quantify the HIL concentrations. In the proposed work, we have demonstrated HIL detection at shorter optical path length and with plasma with slight impurities. A system is developed with multi-LED illumination and an algorithm is developed to retrieve the concentration of free Hb, Icterus and Lipemia from the plasma sample containing impurities such as stray RBCs. In this work, we will discuss about the performance of a multi-LED system and the underlying algorithm.

We are developing micropreconcentrators based on micro/nanotechnology to detect trace levels of volatile organic compound (VOC) gases contained in human and canine exhaled breath. The possibility of using exhaled VOC gases as biomarkers for various cancer diagnoses has been previously discussed. For early cancer diagnosis, detection of trace levels of VOC gas is indispensable. Using micropreconcentrators based on MEMS technology or nanotechnology is very promising for detection of VOC gas. A micropreconcentrator based breath analysis technique also has advantages from the viewpoints of cost performance and availability for various cancers diagnosis. In this paper, we introduce design, fabrication and evaluation results of our MEMS and nanotechnology based micropreconcentrators. In the MEMS based device, we propose a flower leaf type Si microstructure, and its shape and configuration are optimized quantitatively by finite element method simulation. The nanotechnology based micropreconcentrator consists of carbon nanotube (CNT) structures. As a result, we achieve ppb level VOC gas detection with our micropreconcentrators and usual gas chromatography system that can detect on the order of ppm VOC in gas samples. In performance evaluation, we also confirm that the CNT based micropreconcentrator shows 115 times better concentration ratio than that of the Si based micropreconcentrator. Moreover, we discuss a commercialization idea for new cancer diagnosis using breath analysis. Future work and preliminary clinical testing in dogs is also discussed.

3D pathology is intrinsically dependent on 3D microscopy, or the whole tissue imaging of patient tissue biopsies (TBs). Consequently, unsectioned needle specimens must be processed whole: a procedure which cannot necessarily be accomplished through manual methods, or by retasking automated pathology machines. Thus "millifluidic" devices (for millimeter-scale biopsies) are an ideal solution for tissue handling/preparation. TBs are large, messy and a solid-liquid mixture; they vary in material, geometry and structure based on the organ biopsied, the clinician skill and the needle type used. As a result, traditional microfluidic devices are insufficient to handle such mm-sized samples and their associated fabrication techniques are impractical and costly with respect to time/efficiency. Our research group has devised a simple, rapid fabrication process for millifluidic devices using jointed skeletal molds composed of machined, reusable metal rods, segmented rods and stranded wire as structural cores; these cores are surrounded by Teflon outer housing. We can therefore produce curving, circular-cross-section (CCCS) millifluidic channels in rapid fashion that cannot normally be achieved by microfabrication, micro-/CNC-machining, or 3D printing. The approach has several advantages. CLINICAL: round channels interface coring needles. PROCESSING: CCCS channels permit multi-layer device designs for additional (processing, monitoring, testing) stages. REUSABILITY: for a biopsy/needle diameter, molding (interchangeable) components may be produced one-time then reused for other designs. RAPID: structural cores can be quickly removed due to Teflon®'s ultra-low friction; housing may be released with ethanol; PDMS volumes cure faster since metal skeleton molds conduct additional heat from within the curing elastomer.

Dimensional characterization of microfluidic circuits were performed using three-dimensional models constructed from OCT images of such circuits. Were fabricated microchannels on the same BK7 glass plate, under different laser ablation conditions and substrate displacement velocity in relation to laser beam. Were used the following combination of energy, from 30 μJ to 60 μJ and velocity from 588 mm/min to 1176 mm/min, at 1 kHz laser repetition rate and 40 fs of pulse duration (FWHM). For OCT imaging we used an OCP930SR (Thorlabs System Inc) with 930 nm central wavelength, 6 μm of lateral and axial resolution, and image of 500 x 512 pixel corresponding to 2.0 mm x 1.6 mm of lateral and axial scans respectively at 8 frames per second. We also characterized devices like, micropumps, microvalves and microreactors. It was possible register the micropumps and valves in action in real time. Using the OCT images analyses was possible to select the best combination of laser pulse energy and substrate velocity. All the devices were made in raster protocol, where laser beam pass through the same path in a controlled number of times, and with each iteration more material is removed and deeper the channels remain. We found a deformation at the edge of fabricated structures, due to velocity reduction of substrate in relation to laser beam, which causes more laser pulses superposition in these regions, and more material is ablated. The technique was thus evaluated as a potential tool to aid in the inspection of microchannels.