This PDF file contains the front matter associated with SPIE Proceedings Volume 11235 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Fused silica glass is an important material for microfluidics. Until recently, microstructuring of glass has been challenging, requiring hazardous etching processes based on hydrofluoric acid or laser-based ablation methods. Classical etching processes can only achieve 2.5-dimensional microfluidic channels, which need to be sealed by bonding in a subsequent step. We have previously demonstrated a concept for fabricating and structuring fused silica glass using silica nanocomposites. These nanocomposites can be structured like a polymer, e.g. via UV-casting or stereolithography printing. After the structuring process, the components are converted into transparent fused silica glass via thermal debinding and sintering. However, the production of three-dimensional microchannels of sizes between 1-100 μm in fused silica remains a challenge. We have therefore developed a novel process, which we call sacrificial template replication (STR), which allows the fabrication of truly arbitrary embedded microchannels in transparent fused silica glass. To achieve microchannel formation, a polymeric template is embedded in the nanocomposite, which is subsequently removed during the thermal debinding process and leaves the inverse cavity after the sintering process. Since the templates are removed in the gas phase, there is no risk for material redeposition or channel blocking. Due to the thermal removal of the template many different templates can be used such as simple nylon threads, a 2.5- dimensional lithographically structured photoresists or highly complex microstructures fabricated via direct laser writing. Using this technology complex microfluidic channels can be fabricated with micron resolution. In this work we demonstrate the usage of these structures in “chemistry-on-chip” applications.

Precise and fast structuring polymeric materials is important for almost all applications in microsystems engineering, microfluidics and microoptics. In addition to 3D printing and soft lithography, grayscale lithography is a promising technique for structuring of complex geometries. It allows for the direct fabrication of relief structures, such as microoptical lenses and microfluidic channel structures, by illuminating a photo-curable material with a light pattern of gradually changing light intensity. However, standard grayscale resists are limited in terms of penetration depth and contrast: a low contrast, i.e. a flat slope of the polymerization rate vs. exposure dose curve is desired for generating accurate grayscale patterns of high resolution. The achievable polymerization depth of these patterns is limited. Hence we have developed a new photoresist for grayscale lithography that makes various polymerization depths independently accessible. The acrylate-based photoresist contains a combination of different initiators and absorbers, which can be polymerized at different wavelengths from ultraviolet to visible light, producing individual polymerization depths, each with a low contrast. Due to the wavelength-dependent absorptions of the initiators and absorbers, the different polymerization depths are addressed independently. The intensity gradients were generated using a custom-built maskless microlithography system based on a digital mirror device (DMD). In this work we will demonstrate that 3D structures with a high complexity can be fabricated fast and easily via grayscale lithography using the multi-level photoresist

Research on hemodynamics has required narrow pipes called microchannels which mimic human blood vessels with Y-branch structures. However most of the conventional polymer microchannels have been fabricated by means of the imprint method, so in general, their cross-sectional shapes are square or rectangle. In this paper, photo-curable PDMS is applied to Mosquito method for fabrication of microchannel with circular cross section. Mosquito method is invested by us and is originally used for fabricating polymer optical waveguides with a circular core and various writing pattern. We confirmed straight microchannel and Y-branched microchannel. We also confirmed the function as a microchannel.

We report a novel solution for semi-quantitative detection of C-reactive protein (CRP), a common inflammatory marker, using a multi-path lateral-flow device (LFD) fabricated via the precise partitioning of the single flow-path of a standard LFD using a laser direct-write technique. The multiple isolated flow-paths allow detection of different concentrations by individually setting different cut-off levels. The semi-quantitative readout is observed via simple appearance/absence of test lines without the need for a reader or further analyses. We have successfully demonstrated the use of these multi-path LFDs for semi-quantitative detection of CRP and will present validation in human samples.

Jet injectors are medical injecting devices that use a high-pressure jet of liquid to replace hypodermic needles. The current approach of the jet generation by gas cartridge, loaded spring or piezo actuator are relatively bulky and are meant to be used for the superficial part of the body. In this study, we present jet generation employing the laser-induced liquid breakdown realized through optical fibres inserted into the round capillary with 0.3 mm inner diameter, and 1,2 mm outer diameter. Using the ultra-fast camera we can observe jet velocity depending on the laser fluence. We further examine the ability to inject liquid into the hydrogel models mimicking mechanical properties of soft tissues. This technology allows shrinkage of the jet injector device into the scale it could be used as a minimally invasive device in an endoscopic probe.

In this work, we present a new microspectrometry FTIR-based biosensor for the analysis of sugar based solutions using various solvent and various types of sample handling support (SHS). We used methanol as solvent because it does not interact with infrared (IR) beam. In addition, it ensures a rapid evaporation in order to form a thin layer of targeted molecules on the conventional SHS. The later consists of a total reflective mirror (TRM). Because of methanol toxicity, we developed a new setup for aqueous samples analysis based on accelerated solvent evaporation. The achieved limit of detection (LOD) using the developed biosensor was 3 mM for both, Glucose and Fructose molecules.

In this paper and presentation, we will focus on different aspects of backscattering-based wireless communication and power transfer to small biomedical implants. We will present three different antenna topologies for data and power transfer through tissue, in vitro and in vivo studies on implantable intracranial pressure (ICP) sensors and give insight and analysis on wireless link reliability in tissue environment. We will also present radio frequency identification (RFID) -based implant platform and communication method. Moreover, we will focus on differences and challenges of in vivo environment compared to laboratory phantoms and tissue models. In our studies, different types of implantable antennas have been tested to investigate reliability, accuracy and sensitivity of the brain implants: a hybrid near field-far field system with a piezoresistive sensor for ICP monitoring [2], [4], a UHF band spilt-ring resonator system [3] and LC tank based miniature implantable antenna [5]. This paper will present these implant antennas and wireless power transfer in tissue environment present in human head.

Oral cavity cancer is one of the most common malignancies. Development of immunoassay based biosensor for interleukin-8 (IL-8) protein is required. The miniaturization of the device is also necessary in order to provide ready-touse portable diagnostic tools (point of care diagnostic) for clinical uses. In the current study, a compact, portable and reliable biomarker detecting and analyzing system is presented. The light absorption analysis was performed by a low-cost and portable optical sensor device. We used a programmable microcontroller unit (MCU) to operate the device. A digitalto-analog converter (DAC) was used to deliver a modulating signal to LEDs, and then the modulated light excited the samples in the microfluidic detection chamber. The signals from the sample and control group were obtained by two photodetectors individually. The photodetectors were amplified and demodulated through the lock-in amplifier, and digitized by analog-to-digital converters (ADC) to the MCU. After that, the analyzed data was uploaded to the smartphone via Bluetooth. The device demonstrates a good measurement accuracy and shorter detection time compared to conventional methods.

This paper describes a proof of concept of a microfluidic dipole to sample cerebral fluid. It consists of a portable microfluidic probe which injects a buffer in one inlet and draws it from the other one after passing through a contact zone with the external liquid. Finite elements method modelling (FEM) shows a very stable liquid flow across the complete probing area. Furthermore, we determined that a design generating turbulence is likely to be more useful to capture brain molecules. Molecules displacement due to diffusion phenomena takes about 25 ms to diffuse over a 1 mm probe gap. Finally, our experiment showed that, to obtain a stable flow without turbulence the maximum inlet and outlet pressure is 0.05 mPa for the two tested configuration of dipole.

Cardiovascular disease (CVD), the leading cause of death worldwide, has been viewed as one of the major problems for wealthy and industrialized nations for decades, and the need for rapid detection and timely diagnosis has the utmost importance. Cardiac troponin I (cTnI) is a promising biomarker for early diagnosis of acute myocardial infarction (AMI). Hence, the development of immunoassay based biosensor for cTnI is necessary. Over the past decades, there have been extensive researches regarding cTnI detection, including colorimetric, fluorescence, paramagnetic, electrochemical, and surface plasmon resonance. However, conventional laboratory methods are time-consuming and require expensive and bulky equipment. In light of this, the need for point of care testing becomes more crucial. Here, we use a programmable microcontroller unit (MCU) to operate the device. A digital-to-analog converter (DAC) is used to deliver a modulating signal to LEDs, and then the modulated light excites the samples in the microfluidic reaction wells. The signals from the sample and control group are obtained by two photodetectors individually. They will be amplified and demodulated through the lock-in amplifier and digitized by analog-to-digital converters (ADC) to the MCU. And the collected data will be presented on the device and uploaded synchronically to the smartphone via Bluetooth. The whole processing time is less than 5 minutes. Next, we use the microfluidic platform to simplify complicated laboratory procedures. In our study, we focus on using cTnI to detect the samples in the human serum or blood. In order to solve low efficacy caused by the non-specific binding, we used Zwitterionic carboxybetaine disulfide (CB) as a self-assembled monolayer in the experimental design. The use of self-assembled monolayer can not only decrease non-specific binding problem but also shorten the analysis time.

Neuro-electrophysiology allows scientists to investigate the underlying electrical properties that constitute brain neural network assembly. Developing tools to study these properties is a rapidly-evolving research field, and recent advancements in micro electrode arrays (MEAs) is opening a new frontier in long-term data acquisition. MEA microfabrication techniques have advanced over the years and led to different types of electrodes. The objective of this study was to optimize MEA design featuring multiple wells per electrodes (MW-MEA), to improve the recording efficiency of MEAs used for in vitro electrophysiological recordings. Methods: Two multi-well electrode designs (5 wells with diameter of 20 μm vs. 6 wells with diameter of 15 μm) were evaluated. Peak to peak signal amplitude of the recorded signals and the noise levels were studied and the signal to noise ratios (SNR) were determined. Results: The signal amplitudes recorded by electrodes with 6 wells (1060.3 μm² ) was higher than those recorded by 5-wells electrodes (1570.8 μm² ), while the noise level remained identical in both designs (31.3 μv ± 10.2). As such, the SNR recorded by the 6-wells electrodes showed a 1.8-time increase, compared to the electrodes with 5 wells, although the diameter of the wells in the former design was smaller. The results of this study demonstrated an inverse relation between SNR and open surface area of electrodes. Significance: The identified relation between electrode well characteristics and MW-MEA performance and design optimization can improve signals’ resolution during long-term spontaneous extracellular recordings and thus the quality of brain cell activity recordings.

The emission filter plays a key role in resolving a modest-quality image of the lens-free fluorescent imager. The complementary structure of an interference filter and absorption filters exhibits a high-rejection ratio, corresponding to the lens-based fluorescence device. However, existing fabrication methods are facing challenges to reach a reasonable filter thickness for low invasiveness. It is difficult to deposit interference filters on the polymer-based absorption filter and CMOS die directly. Conversely, the interference is fragile and easy to crack so that transferring from its substrate to the image sensor is a fatiguing task. Here we report composite filter fabrication using laser lift-off (LLO) and silicon plasma etching. The LLO utilized high energy laser to separate the interference filter from the glass substrate, whereas the plasma etching tailored SiF₆ gas to completely annihilate silicon-substrate whereby the filter was deposited beforehand. As a result, a narrow-size filter is successfully fabricated by LLO, yet a crack issue for a larger sensor size remains unsolved. On the other hand, the plasma etching produced large-size and spotless filters with relatively high reproducibility. Additionally, this method offers multiple device fabrication in a single process, which, we expect, could intensify largescale lens-free fluorescent imager applications in the future.

Poly(dimethylsiloxane) (PDMS) is one of the widely-used materials to fabricate microfluidic devices because of its facile handling, optical transparency and elastic mechanical properties. However, this polymer has its limitations if chemical, thermal and mechanical stability are needed for novel devices such as flow through “chemistry-on-chip” synthesis. Fused silica glass or borosilicate glass are indubitably the materials of choice for chemical synthesis due to its extraordinary chemical and thermal stability as well as its optical transparency. Microfluidic glass devices are however notoriously difficult to fabricate and usually require wet chemistry or dry etching using hazardous chemicals like hydrofluoric acid (HF). To overcome these fabrication issues, we have developed the Glassomer process that renders the structuration of fused silica glass like a polymer possible including technologies like softlithographic replication or stereolithography printing. In order to take the concept of “chemistry-on-chip” to the next level, electronics need to be integrated into the Glassomer process for the detection and localization of droplets inside microfluidic devices, for electrochemical analysis and electrochemical synthesis. In this work, we show that platinum electrodes can be integrated into the process using wires and sputtering of platinum in the polymeric state. The samples are subsequently converted into transparent fused silica glass via thermal debinding and sintering. We demonstrate that with our process the fabrication of glass microfluidic devices containing electronic conductors is feasible and facile to obtain and that they can be used to detect changes of conductivity

Chemically resistant polymer materials are of great interest due to their versatile implementation in a broad range of applications, including the design of robust microfluidic devices. While flow cells, conventionally fabricated by using poly(dimethylsiloxane) (PDMS), are hardly resistant toward organic solvents, fluorinated materials are chemically inert. However, focusing on the latest developments in microfluidic device design via high-resolution additive manufacturing, e.g., based on micro-stereolithography (μSL), only a few resin formulations have been demonstrated suitable for 3D printing chemically resistant polymer objects. Here, we introduce a homemade resin formulation based on 1H,1H,6H,6H-Perfluoro-1,6-hexyl diacrylate (PFHDA) for high-resolution 3D printing utilizing μSL. By investigating the optical dose, the wettability, the resistance toward organic solvents, and the minimal resolution achievable, we fabricate inner structures down to 200 μm. Finally, water-in-oil (W/O) emulsions are generated in a 3D-printed droplet maker with planar microchannel geometry made from the PFHDA-based resin yielding droplets with an average diameter of 271 μm ± 26 μm. The presented material is resistant against commonly used organic solvents including THF, DMF and toluene with a swelling below 1.5% and shows no solvent-induced damage to the micro-printed structure, which makes the PFHDA-based resin a promising base material for several potential applications such as organic synthesis in microreactors.

A 3D centrifugal cartridge with gravity valve, capillary valves, and Coriolis switching valve was designed, fabricated, and tested for Solid Phase Extraction (SPE). In particular, the novel three-dimensional gravity valve helps to release reagents in not-sequentially increased rotation speeds. The sequential control of these valves was simply achieved by manipulating the rotating direction and speed of the cartridge. The prototype microfluidic cartridge was 3D printed with a FDM printer and experimentally tested. Anthracene, which was one of the Polycyclic Aromatic Hydrocarbons (PAHs), was used as the target analyte and tested. C18 was used as the stationary sorbent and fluorescence method was adopted to detect anthracene. The concentrations of the anthracene testing samples were 1μg/L (1ppb), 5μg/L, and 10μg/L (anthracene/water), respectively. The volumes of testing sample and eluent (nonane) were 10mL and 1mL respectively. Experiments showed that 7 times of enrichment of the original samples were achieved. This centrifugal SPE system could be potentially used as a portable on-situ pollutant enrichment and detection device.

Current in vitro cancer models used for screening potential new therapeutic agents are often 2D monolayers of cells grown on the bottom of a petri dish or culture flask. These simplistic models lack many of the important biological features of in vivo tissue growth, such as the presence of an extracellular matrix (ECM) and cell interactions associated with this in a 3D structure. The use of spheroids for drug testing has gone some way to address the limitations of 2D cultures, however spheroids are still typically handled in static environments that neglect important physical aspects of the microenvironment present in vivo, such as fluid flow and associated shear stresses. In addition, assays involving spheroids still require many manual pipetting steps in which fluid is replaced in a single fluidic operation which is labor intensive, can be damaging to spheroid structural integrity and is an action that is physiologically incorrect. Here we present a microfluidic platform for the high-throughput trapping, culture and exposure of 3D co-culture spheroids to drugs under physiologically relevant fluid flow. The device is self-supportive, allowing multiple devices to be in an incubator at once without peripheral pumps. Spheroids can be monitored in situ with microscopy and the device is designed such that spheroids can be recovered for quantitative off-chip analysis. As a first demonstration, the effectiveness of co-delivering ultrasound (US) triggered microbubbles (MBs) with doxorubicin (DOX) was evaluated. Spheroids exposed to 3 μM DOX co-delivered with MBs showed a 51% reduction is spheroid viability compared to a 25% reduction in viability of free DOX alone.

Wire-free power supplies provide portability, flexibility and cost efficiency as they reduces hardware complexity. Thus, in this paper we designed a portable pH sensor based on a microbial fuel cell (MFC) as a wire free energy source. Our MFCs supplied 0.127 mW to power our ultra-low power portable pH sensor. The error of the newly designed pH sensor is less than 5% when pH is between 4 and 10. Also it provides, an autonomy of 4 hours when the pH sensor is continuously used.

Average iron content of ferritin has a potential to serve as a biomarker for early identification of high-risk trauma patients at point-of-care (PoC). Appropriate therapies can then be administered to reduce morbidity and mortality. Currently, protein and iron levels are measured separately using enzyme-linked immunosorbent assay (ELISA) and UV or atomic absorption spectroscopy (AAS) respectively, but the use of two completely different methods adds to the complexity and analysis time of the combined measurement. As a result, these methods are unsuitable for PoC analysis. To address this gap, we report a biosensor for measuring the average iron content of ferritin in a single step. The biosensor was based on a dye-doped leaky waveguide (LW), which operates in the entire visible wavelength range, and hence allowed the measurement of differences in the optical dispersion of ferritin and apoferritin to determine the average iron content of the protein. The LW biosensor comprised a 1.54 micron thick mesoporous chitosan slab waveguide with immobilized antibodies against ferritin/ apoferritin to measure the optical dispersion of 110 nM protein. Based on the baseline noise, the limit of detection for this method is ~700 pM for ferritin/ apoferritin. The biosensor has a significant potential for PoC measurement of the average iron content of serum ferritin and, in future, the total protein cencentration.

To monitor the healthiness of cells, it is very important to develop quick ways to characterize cells with the diseased and normal mitochondria. Thus, we can take measures to prevent potential development of mitochondria-related diseases. Physical study and systemic proof of concept by engineering method to perform quick diagnosis of the normal and diseased mitochondria have not been well achieved yet. In this study, we used insulator dielectrophoresis (i-DEP), by utilizing the intrinsic dielectric response of a cell to an external AC electric field to differentiate cells containing partially diseased and normal mitochondria to test if we can select diseased mitochondria-containing cells but not the normal cells. We found that it is possible to detect the diseased and healthy mitochondria in cells without breaking the cell membrane. Taking advantage of the dielectrophoresis, DEP principle, we may develop a quick diagnostic method to detect diseased mitochondria in living cells.

The prevention of toxic pathogens such as mycotoxins is a constant challenge in food production. We present a microfluidics-enabled system for the identification of pathogens in grain dust, thereby allowing for the detection of such pathogen already in the early raw material stage prior further processing. In order to be utilized in such environment, the system has to be compact and rugged. This is realized by miniaturizing both the analytical workflow (competitive fluorescence immunoassay) using a fully integrated microfluidic cartridge as well as the instrument to operate the cartridge. We have been able to show similar performance of microfluidic chip-based assays compared to standard ELISA plates.

Microfluidic reactors have become increasingly important for chemical synthesis. Alumina is an interesting material for the fabrication of microfluidic chemical reactors since it shows a high thermal and chemical stability, high mechanical strength and hardness as well as a relatively high thermal conductivity. However, microfluidic alumina reactors have so far been only barely structured using rapid prototyping approaches. Rapid prototyping however has gained great interest in microfluidics in recent years allowing the test of a wide variety of channel designs in an early stage of the development process. In this work, we demonstrate soft replication of photo-curable alumina nanocomposites for the fabrication of microfluidic reactors. Using this approach a microchannel with tens of micron resolution can easily be fabricated. The whole process takes less than 48 h.

Single cell analysis has become a crucial goal since cellular heterogeneity was acknowledged as one of the greatest challenges in cancer therapeutics. Radioactive probes can play an important role in single cell study thanks to its unique capability of tracking small molecules with minimal modification of their chemical structure. Our lab has recently developed a new technique known as radioluminescence microscopy (RLM) to measure the amount of radiotracer in single cells. Yet, RLM can image only up to about 100 cells and lacks capability of integrating with subsequent sample processing such as cell sorting. Here we introduce a robust, high throughput single cell radiometry based on radiofluorogenesis and droplet optofluidics. As an example, we quantitated [¹⁸F]-fluorodeoxyglucose radiotracer uptake in single human breast cancer cells and assessed cellular heterogeneity in single cell metabolism.

We introduce Optofluidic PlasmonIC (OPtIC) microlenses to overcome the shortcomings of existing optical chromatography techniques by eliminating the need for sophisticated instrumentation and pre- cise alignment requirements. Our sub-wavelength thick (~200 nm thick) OPtIC microlenses offer objective-free focusing and self-alignment of optical and fluidic drag forces and present a facile platform for selective separation of exosome size bioparticles. By allowing direct coupling of collimated broadband light to realize strong optical scattering forces at a focal point, extremely small footprint (4 μm × 4 μm) OPtIC microlenses open the door for drastically multiplexed optical chromatography and high-throughput sample processing capability.

An implantable image sensor device is extremely small and lightweight owing to the use of a specially designed complementary metal oxide semiconductor (CMOS) image sensor. It is intended to be applied in in-vivo brain function imaging under free behavior of an observation target such as a mouse. Because of its low invasiveness, it is suitable for the simultaneous imaging of the deep brain along with several other regions of the brain, and for long-term observations. In order to realize low invasiveness, it is required to perform contact imaging without using a lens. This gives rise to a different set of challenges from that faced by microscope systems that use a general lens. In this study, we developed a light source suited for the in-vivo implantation of a fluorescence imaging system to facilitate green fluorescence observation. A thinned InGaN-based blue LED was used as an excitation light source. Normally, an LED has an emission bandwidth that is too broad for fluorescence imaging. In the proposed device, in addition to the interference filter, absorption layers are added in order to remove the unwanted light emission component by using a different strategy. The interference filter used was obtained by transferring a long-pass filter formed on a quartz glass filter image onto a fiber optic plate (FOP) with a low numerical aperture (NA) by the laser lift-off (LLO) method. The interference filter showed sufficiently high performance as an excitation filter even after it was transferred to the light source. The absorption layers composed of a low-NA FOP and a blue absorption layer are used to remove unwanted components. Light rays with a high incident angle, leak through the interference filter when the absorption layers are not present. On the other hand, the unwanted components in the emission bandwidth were successfully reduced in the proposed structure.

In this work, we report a fast and efficient in-situ growth method of Zinc-Oxide nanowires (ZnO-NWs) and the real-time monitoring of NW growth over wide microfluidic chambers. The ZnO-NW hydrothermal synthesis is carried out in dynamic mode involving a continuous flow of the growth solution inside the microfluidic chamber. The biomimetic flow distribution tree is designed as input and output stages for the chamber to ensure uniform distribution of growth solution flow aiming to produce uniform NWs on the wide chamber. The real time monitoring is achieved by continuous acquisition of UV-vis spectra of the ZnO-NWs during the growth, which is achieved for the first time to the best of the author’s knowledge.

Cell counting is a popular method for rapid diagnosis of various infectious diseases such as tuberculosis, malaria and typhoid. Cell counting is often performed using a flow cytometer, which in most case, is bulky and expensive, unsuitable for use in low-resource settings. In the recent years, electric impedance flow cytometry (IFC) platforms have gained popularity for cell counting due to their portability and low cost compared to traditional flow cytometers. However, the electronics used in conventional IFC platforms are manufactured in specialized cleanrooms, which increases the cost per device and hinders large scale production of such devices in resource-poor and developing countries. To tackle this problem, we report a novel IFC platform with low-cost inkjet-printed electronics which can be easily manufactured with a standard inkjet printer, without the need for specialized cleanrooms and skilled personnel. Unlike traditional IFC platforms, the electronics and the microfluidic devices are kept separate from each other, which makes the electronic apparatus reusable and extends the platform lifetime. Most notably, the cost and complexity of manufacturing our platform is significantly low compared to traditional IFC platforms. Here we demonstrate the utility of our platform to effectively count cells in a sample. We have also demonstrated the utility of our platform for size-based classification of cells by performing model experiments with non-homogeneous oil-in-PBS emulsion. The results indicate that our platform can effectively differentiate oil-droplets of various sizes purely using impedance signatures. This can be extended to differentiate cell populations based on their sizes purely using impedance signatures of single cells.

Regenerative medicine has increasingly made use of adult stem cells in the last years (1, 2). Micro-engineering a biomimetic three dimensional structure provides a realistic approach for stem cell niche studies, and further translational applications. A promising approach for engineering artificial stem cell niches is provided by high-throughput microfluidic technologies. In this work, a droplet-based microfluidic-assisted encapsulation device for the generation of multi-layered cellular structures on demand using alginate and Puramatrix is presented. This novel technology is based on gravity-driven flows, passive mixing principle and a gelation system where the use of a double laminar oil flow where only one contains the cross-linking agent allows both the uniform gelation of the inner core and the continuous generation of a stream of cross-linked hydrogel beads. The soft consecutive coating of the inner core with a second and a third layer without exposing the encapsulated cells to external forces that might reduce their viability represents a promising technology towards 3D stem cell encapsulation. Furthermore, we demonstrate the suitability of the presented technology for encapsulation of stem cells by using human Mesenchymal Stem cells (hMScs) and human Hematopoietic stem cells (hHScs). Preliminary results demonstrate a niche model capable of mid-term culture of primitive hHScs in a microfluidic environment. Therefore, the presented method could apply for the artificial reconstruction of the stem cell niche components as an efficient approach to study stem cell behaviour in vitro under controlled conditions, opening a wide field of potential applications within uTAS for 3D cell culture and tissue engineering applications.