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Microfluidics provides a platform for efficient and transportable microanalysis, catalyzing advancements in fields such as biochemistry, materials science, and microbial ecology. While the analysis is cost-effective, standard device fabrication techniques are disproportionately expensive and specialized. A commercially available desktop cutting plotter provides an accessible method for rapidly fabricating microfluidic devices at extremely low costs. The optimized technique described in the present work enables fabrication of microchannels with dimensions as small as ∼100 μm. Straightness of channel walls is comparable to other common fabrication techniques but achieved here at a fraction of the cost and fabrication time. Solute dispersion experiments are performed using the rapidly prototyped channels to measure the effective dispersion coefficient in laminar flow through rectangular channels. The results of these experiments compare favorably to predictions from classical Taylor-Aris dispersion theory. This note provides all necessary tools for researchers and educators to seamlessly apply the desktop cutter fabrication technique. Materials list, fabrication instructions, and detailed channel characterization results are available in the supplementary material.

This paper presents the development of a novel cross-axis countercurrent chromatographic instrument (CCCI) with six separation columns, including design, dynamics, optimization, prototype construction, and experimental validation. The conceptual design and the structural design of the cross-axis CCCI are performed while considering the requirements for the separation operation and design. The dynamic analysis is carried out in order to guarantee the local balance and the global balance for the CCCI. The relationship between the mechanical structure parameters and partition efficiency is investigated by analyzing the effect of mechanical structure parameters on the centrifugal force field. By virtue of the modal analysis of the mechanical structure, the critical speed and the weak link of the CCCI are achieved. Aiming at the problem of the weak link, the structural optimization is done. The presented CCCI has six separation columns distributed around the central revolution axis, and it has more separation columns than that of the existing chromatographic instrument. The CCCI has an axial symmetry structure in the three-dimensional space. Thus it can have better dynamics stability than the CCCI having less separation columns with a symmetry structure in the plane. A physical prototype is built, and then the partition efficiency and its effect factors are tested by the single experimental variable method. The results show that the CCCI runs smoothly and has a good retention rate of stationary phase. It is also proved that the developed CCCI has a good partition efficiency on bovine serum albumin and lysozyme.

Microchannels made of fluoropolymers show potential merits due to their excellent solvent resistance, but such channels have not been widely used because of the complexity to fabricate them. This communication describes a method to prototype microfluidic devices using fluoropolymer films. The fabrication requires only two steps; cutting fluoropolymer films with a desktop cutting plotter and applying heat and pressure to laminate them. The method is rapid, simple, and low-cost. The conditions for heat press were identified for two common fluoropolymers: polytetrafluoroethylene and fluorinated ethylene propylene. The laminated films were confirmed to remain sealed with an internal pressure of at least 300 kPa. The fabricated devices were tested for the resistance to a set of organic solvents that would not be compatible with typical devices fabricated in polydimethylsiloxane. To highlight the potential of the fluoropolymer devices fabricated in this method, generation of droplets in a continuous stream of organic solvent using a T-junction channel was demonstrated. Our method offers a simple avenue to prototype microfluidic devices to conduct experiments involving organic solvents such as organic chemistry and in-channel synthesis of microparticles.

With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks.

Here, we present an inexpensive rapid-prototyping method that allows researchers and children to quickly assemble multi-layered microfluidic devices from easily pre-fabricated building blocks. We developed low-cost (<$2) kits based on laser-cut acrylic building block pieces and double-sided tape that allow users to generate water droplets in oil, capture living cells, and conduct basic phototaxis experiments. We developed and tested a 90-min lesson plan with children aged 12-14 yr and provide here the instructions for teachers to replicate these experiments and lessons. All parts of the kit are easy to make or order. We propose to use such easy to fabricate kits in labs with no access to current microfluidic tools as well as in classroom environments to get exposure to the powerful techniques of microfluidics.

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes.

Cell culture in microfluidic systems has primarily been conducted in devices comprised of polydimethylsiloxane (PDMS) or other elastomers. As polystyrene (PS) is the most characterized and commonly used substrate material for cell culture, microfluidic cell culture would ideally be conducted in PS-based microsystems that also enable tight control of perfusion and hydrodynamic conditions, which are especially important for culture of vascular cell types. Here, we report a simple method to prototype perfusable PS microfluidics for endothelial cell culture under flow that can be fabricated using standard lithography and wet laboratory equipment to enable stable perfusion at shear stresses up to 300 dyn/cm(2) and pumping pressures up to 26 kPa for at least 100 h. This technique can also be extended to fabricate perfusable hybrid PS-PDMS microfluidics of which one application is for increased efficiency of viral transduction in non-adherent suspension cells by leveraging the high surface area to volume ratio of microfluidics and adhesion molecules that are optimized for PS substrates. These biologically compatible microfluidic devices can be made more accessible to biological-based laboratories through the outsourcing of lithography to various available microfluidic foundries.

Being small in size and weight, piezoelectric transducers hold unique positions in vibration sensing and control. Here, we explore the possibility of building a compact vibration isolation system using piezoelectric sensors and actuators. The mechanical resonances of a piezoelectric actuator around a few kHz are suppressed by an order of magnitude via electrical damping, which improves the high-frequency response. Working with a strain gauge located on the piezoelectric actuator, an auxiliary control loop eliminates the drift associated with a large servo gain at dc. Following this approach, we design, optimize, and experimentally verify the loop responses using frequency domain analysis. The vibration isolation between 1 Hz and 200 Hz is achieved and the attenuation peaks at 60 near vibration frequency of 20 Hz. Restrictions and potentials for extending the isolation to lower vibration frequencies are discussed.

Blood Flow Velocity, Erythrocytes cytology, Humans, Microfluidic Analytical Techniques, and Models, Cardiovascular

This article presents a simple and novel method for the fabrication of cylindrical microchannels in polymer or biopolymer substrates. This process results in highly regular, cylindrical microchannels, suitable both to the transport of liquid and the transmission of light. This method eliminates issues associated with positioning tolerances characteristic of conventional fabrication techniques, such as soft lithography. Such devices hold great promise in the field of biomedical engineering by providing a true cylindrical profile for microflow studies and vascular modeling, as well as the ability to optically analyze injected biological samples. An evaluation of these devices is performed by real time optical imaging of blood flow.

A compact low-cost cryocooling system has been designed, constructed, and tested at SLAC National Accelerator Laboratory. The cooling power is provided by natural convection and phase change of the liquid nitrogen. The initial application was to cool silicon crystal optics to the sub-100 K range. A silicon crystal of dimension (width × depth × height) 50 × 50 × 30 mm 3 has been used with an electric heater on the top surface in this prototyping test. This system can effectively provide more than 80 W of cooling power to the optics with a consumption of liquid nitrogen less than 2.1 l/h. The vibration of the silicon crystal was monitored during the tests with added electric heater power on the crystal. The vibration of the silicon crystal due to liquid nitrogen boiling is negligible.

Free liquid jets are a common sample delivery method in serial femtosecond x-ray (SFX) crystallography. Gas dynamic virtual nozzles (GDVNs) use an outer gas stream to focus a liquid jet down to a few micrometers in diameter. Such nozzles can be fabricated through various methods (capillary grinding, soft lithography, digital light processing, and two-photon polymerization) and materials, such as glass, polydimethylsiloxane, and photosensitive polyacrylates. Here, we present a broadly accessible, rapid prototyping laser ablation approach to micromachine solvent-resistant and inert Kapton polyimide foils with highly reproducible geometric features that result in 3D flow-focused GDVNs suitable for crystallography experiments at synchrotrons and free-electron laser facilities.

The negative tone photoresist SU-8 permits the creation of micrometer-scale structures by optical lithography. It is also the most used photoresist in soft lithography for the fast-prototyping of microfluidic devices. Despite its importance, the effect of capillary forces on SU-8 multi-layering onto topographical features has not been thoroughly studied. In particular, the profile of the added layer has not been examined in detail. The overlaying process exhibits a set of distinct behaviors, or regimes, depending on the relative thickness of the overlay and the underlying rectangular pattern. We demonstrate how capillary effects control the profile of multi-layer microchannels in a predictable manner. We derive a simple static model to describe the evolution of the overlay as a function of dimensionless geometric parameters. Our study provides a critical understanding of the parameters that govern multi-layer spin coating.
(Copyright © 2020 Author(s).)

We established a production method of a millimeter-wave absorber by using a 3D-printed mold. The mold has a periodic pyramid shape, and an absorptive material is filled into the mold. This shape reduces the surface reflection. The 3D-printed mold is made from a transparent material in the millimeter-wave range. Therefore, unmolding is not necessary. A significant benefit of this production method is easy prototyping with various shapes and various absorptive materials. We produced a test model and used a two-component epoxy encapsulant as the absorptive material. The test model achieved a low reflectance: ∼1% at 100 GHz. The absorber is sometimes maintained at a low temperature condition for cases in which superconducting detectors are used. Therefore, cryogenic performance is required in terms of a mechanical strength for the thermal cycles, an adhesive strength, and a sufficient thermal conductivity. We confirmed the test-model strength by immersing the model into a liquid-nitrogen bath.

We expand upon our recent, fundamental report on solvent immersion imprint lithography (SIIL) and describe a semi-automated and high-performance procedure for prototyping polymer microfluidics and optofluidics. The SIIL procedure minimizes manual intervention through a cost-effective (∼$200) and easy-to-assemble apparatus. We analyze the procedure's performance specifically for Poly (methyl methacrylate) microsystems and report repeatable polymer imprinting, bonding, and 3D functionalization in less than 5 min, down to 8  μ m resolutions and 1:1 aspect ratios. In comparison to commercial approaches, the modified SIIL procedure enables substantial cost reductions, a 100-fold reduction in imprinting force requirements, as well as a more than 10-fold increase in bonding strength. We attribute these advantages to the directed polymer dissolution that strictly localizes at the polymer-solvent interface, as uniquely offered by SIIL. The described procedure opens new desktop prototyping opportunities, particularly for non-expert users performing live-cell imaging, flow-through catalysis, and on-chip gas detection.

A new miniature high-pressure diamond anvil cell was designed and constructed using 3D micro laser sintering technology. This is the first application of the use of rapid prototyping technology to construct high-pressure apparatus. The cell is specifically designed for use as an X-ray diffraction cell that can be used with commercially available diffractometers and open-flow cryogenic equipment to collect data at low temperature and high pressure. The cell is constructed from stainless steel 316L and is about 9 mm in diameter and 7 mm in height, giving it both small dimensions and low thermal mass, and it will fit into the cooling envelope of a standard Cryostream TM cooling system. The cell is clamped using a customized miniature buttress thread of diameter 7 mm and pitch of 0.5 mm enabled by 3D micro laser sintering technology; such dimensions are not attainable using conventional machining. The buttress thread was used as it has favourable uniaxial load properties allowing for higher pressure and better anvil alignment. The clamp can support the load of at least 1.5 kN according to finite element analysis (FEA) simulations. FEA simulations were also used to compare the performance of the standard thread and the buttress thread, and demonstrate that stress is distributed more uniformly in the latter. Rapid prototyping of the pressure cell by the laser sintering resulted in a substantially higher tensile yield strength of the 316L stainless steel (675 MPa compared to 220 MPa for the wrought type of the same material), which increased the upper pressure limit of the cell. The cell is capable of reaching pressures of up to 15 GPa with 600 μm diameter culets of diamond anvils. Sample temperature and pressure changes on cooling were assessed using X-ray diffraction on samples of NaCl and HMT-d 12 .

The reconstruction of an early viola da gamba is considered, using virtual prototyping by means of the finite element method. Based on iconographic sources, previous research has postulated an instrument design lacking a soundpost and a bass bar. This led to the hypothesis of a top plate with variable thickness. In order to investigate the acoustic efficiency of such a design, a finite element model of the instrument is formulated. The structural accuracy of the model is qualitatively verified by comparing calculated modal shapes with those of a reconstructed instrument, visualized with the aid of Chladni patterns and electronic speckle pattern interferometry. Furthermore, simulating the interaction between the vibrating surfaces of the instrument and the surrounding air shows that the posited asymmetric design can radiate sound more efficiently than a design involving a symmetric top plate. However, the asymmetry introduced by the gradually thickening top plate is weaker than that usually enforced by the presence of a soundpost and a bass bar. Therefore, low frequency structural modes of the instrument are less easily excited by a force acting parallel to the top plate.

The use of three-dimensional (3D) printing for the fabrication of microfluidic chips has attracted considerable attention among researchers. This low-cost fabrication method allows for rapid prototyping and the creation of complex structures; however, these devices lack optical transparency, which greatly hinders the characterization and quantification of experiment results. To address this problem, integrating a transparent substrate with a 3D-printed chip is an effective approach. In this study, we present a solvent bonding method of poly(methyl methacrylate) (PMMA) and acrylonitrile butadiene styrene (ABS) thermoplastic materials for the creation of optically detectable 3D-printed microfluidic devices. To achieve an excellent bonding between PMMA and ABS substrates, we used spray coating as a method for the distribution of ethanol solution followed by UV exposure and post-annealing step to improve the bonding strength. We fabricated a microfluidic chip with S-microchannel to characterize the bonding protocol, and other two application-oriented microfluidic chips, including a 3D split-and-recombine-based passive micromixer, and an integrated microchip for the mixing of two streams of liquid prior to the formation of double-emulsion droplets, to evaluate the efficacy of the proposed scheme. As a result, at least eight bars of the bonding strength between PMMA/ABS substrates was achieved, and the ability of producing optically detectable 3D-printed microfluidic devices based on this bonding method was confirmed.

The fabrication of microfluidic chips remains a complex and expensive process requiring specific equipment and protocols, often if not always limited to the most privileged laboratories. As an alternative to the most sophisticated methods, the present paper describes the fabrication of microfluidic chips by an approach that uses coins as positive master for the rapid production of multigeometry chips. All steps of chip production were carried out using inexpensive approaches by low-cost chemicals and equipment. The chips were validated by different "classic" microfluidic tasks, such as hydrodynamic focusing, droplets generation, micromixing, and on-chip cell culture. The use of coins is not only an efficient method for rapid prototyping but also represents an inspiring possibility for the design of new microfluidic chips. Finally, coin-inspired chips could represent a laboratory experiment doable at a high school level.

Serial femtosecond crystallography is a new method for protein structure determination utilizing intense and destructive X-ray pulses generated by free-electron lasers. The approach requires the means to deliver hydrated protein crystals to a focused X-ray beam and replenish them at the repetition rate of the pulses. A liquid-jet sample delivery system where a gas dynamic virtual nozzle is printed directly on a silicon-glass microfluidic chip using a 2-photon-polymerization 3D printing process is implemented. This allows for rapid prototyping and high-precision production of nozzles to suit the characteristics of a particular sample and opens up the possibility for high-throughput and versatile sample delivery systems that can integrate microfluidic components for sample detection, characterisation, or control. With the hybrid system described here, stable liquid jets with diameters between 1.5 µm at liquid flow rate of 1.5 µl/min and more than 20 µm at liquid flow rate of 100 µl/min under atmospheric and vacuum conditions are generated. The combination of 2D lithography with direct 3D printing may streamline the integration of free-form-features and also facilitate scale-up production of such integrated microfluidic devices that may be useful in many other applications such as flow cytometry and optofluidics.