This work was supported by Conacyt, Mexico under grant 312231 of the &#34;Programa de Apoyos para Actividades Cient&#237;ficas, Tecnol&#243;gicas y de Innovaci&#243;n&#34;, and by AMEXCID and Mexican Foreign Relations Ministry (SRE) under grant &#34;Prueba serol&#243;gica r&#225;pida, barata y de alta sensibilidad para SARS-CoV-2&#34;. JAHO thanks Conacyt Mexico for their PhD scholarship.

<ol>
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B., Guevara-Pantoja, P. E., Caballero-Robledo, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capture+efficiency+of+magnetic+nanoparticles+through+the+compaction+effect+of+a+microparticles+column.">Capture efficiency of magnetic nanoparticles through the compaction effect of a microparticles column.</a> Physical Review E. 104 (2), 024603 (2021).</li><li>Gale, B. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+current+methods+in+microfluidic+device+fabrication+and+future+commercialization+prospects.">A review of current methods in microfluidic device fabrication and future commercialization prospects.</a> Inventions. 3 (3), 60 (2018).</li><li>Liu, K., Fan, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoplastic+microfluidic+devices+and+their+applications+in+protein+and+DNA+analysis.">Thermoplastic microfluidic devices and their applications in protein and DNA analysis.</a> Analyst. 136 (7), 1288-1297 (2011).</li><li>Guckenberger, D. J., de Groot, T. E., Wan, A. M. D., Beebe, D. J., Young, E. W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micromilling:+A+method+for+ultra-rapid+prototyping+of+plastic+microfluidic+devices.">Micromilling: A method for ultra-rapid prototyping of plastic microfluidic devices.</a> Lab on a Chip. 15 (11), 2364-2378 (2015).</li><li>Guevara-Pantoja, P. E., Jim&#233;nez-Vald&#233;s, R. J., Garc&#237;a-Cordero, J. L., Caballero-Robledo, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure-actuated+monolithic+acrylic+microfluidic+valves+and+pumps.">Pressure-actuated monolithic acrylic microfluidic valves and pumps.</a> Lab on a Chip. 18 (4), 662-669 (2018).</li><li>Guevara-Pantoja, P. E., Chavez-Pineda, O. G., Solis-Serrano, A. M., Garcia-Cordero, J. L., Caballero-Robledo, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+affordable+3D-printed+positioner+fixture+improves+the+resolution+of+conventional+milling+for+easy+prototyping+of+acrylic+microfluidic+devices.">An affordable 3D-printed positioner fixture improves the resolution of conventional milling for easy prototyping of acrylic microfluidic devices.</a> Lab on a Chip. 20 (17), 3179-3186 (2020).</li><li>Friedrich, C. R., Vasile, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+the+micromilling+process+for+high-aspect-ratio+microstructures.">Development of the micromilling process for high-aspect-ratio microstructures.</a> Journal of Microelectromechanical Systems. 5 (1), 33-38 (1996).</li><li>Malayath, G., Sidpara, A. M., Deb, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+different+materials+response+in+micro+milling+using+four+edged+micro+end+mill+tools.">Study of different materials response in micro milling using four edged micro end mill tools.</a> Journal of Manufacturing Processes. 56, 169-179 (2020).</li><li>Jiang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single+low-cost+microfabrication+approach+for+polymethylmethacrylate,+polystyrene,+polycarbonate+and+polysulfone+based+microdevices.">A single low-cost microfabrication approach for polymethylmethacrylate, polystyrene, polycarbonate and polysulfone based microdevices.</a> RSC Advances. 5 (45), 36036-36043 (2015).</li><li>Sun, Y., Kwok, Y. C., Nguyen, N. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-pressure,+high-temperature+thermal+bonding+of+polymeric+microfluidic+devices+and+their+applications+for+electrophoretic+separation.">Low-pressure, high-temperature thermal bonding of polymeric microfluidic devices and their applications for electrophoretic separation.</a> Journal of Micromechanics and Microengineering. 16 (8), 1681-1688 (2006).</li><li>Tsao, C. W., Hromada, L., Liu, J., Kumar, P., DeVoe, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low+temperature+bonding+of+PMMA+and+COC+microfluidic+substrates+using+UV/ozone+surface+treatment.">Low temperature bonding of PMMA and COC microfluidic substrates using UV/ozone surface treatment.</a> Lab on a Chip. 7 (4), 499-505 (2007).</li><li>Bamshad, A., Nikfarjam, A., Khaleghi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+simple+and+fast+thermally-solvent+assisted+method+to+bond+PMMA-PMMA+in+micro-fluidics+devices.">A new simple and fast thermally-solvent assisted method to bond PMMA-PMMA in micro-fluidics devices.</a> Journal of Micromechanics and Microengineering. 26 (6), 065017 (2016).</li><li>Ogilvie, I. R. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+surface+roughness+for+optical+quality+microfluidic+devices+in+PMMA+and+COC.">Reduction of surface roughness for optical quality microfluidic devices in PMMA and COC.</a> Journal of Micromechanics and Microengineering. 20 (6), 065016 (2010).</li></ol>

The authors have no conflicts of interest to disclose.

An acrylic microfluidic device for immunoassays using nanoparticles as immunosupport was fabricated using a micromilling technique. The method of direct manufacturing on the substrate has the advantage of avoiding the use of a master mold and the time and costs that this implies. However, it is limited to rapid prototyping and high-volume device manufacturing.
Here, we used a previously reported accessory piezoelectric platform for the milling machine12. The platform wa...

In recent years, microfluidics has played an important role in immunoassay techniques1. Miniaturization technology has many outstanding advantages compared to traditional immunoassays, such as reduced sample and reagent consumption, shorter incubation times, efficient solution exchange, and higher integration and automation2.
Furthermore, microfluidic systems in immunoassays, in association with magnetic nanoparticles as immunosupport, considerably reduce incubation times, achieving high detection sensitivity due to the increased surface-to-volume ratio3. Brownian movement of the particles improves the reaction kinetics during the formation of the antigen-antibody complex4,5. Moreover, the magnetic properties of nanoparticles provide the versatility to be integrated into different microfluidic device configurations, making them an ideal candidate for signaling and molecule capture in miniaturized on-chip biosensing systems5. However, magnetic forces are significantly weaker than drag forces at the nanometer scale due to the high surface-to-volume ratio6. Therefore, capturing nanoparticles for crucial immunoassay steps such as washing and detection can be challenging, and a conventional magnet is insufficient4.
An efficient way to manipulate the nanoparticles is the use of a microfluidic magnetic trap formed by iron microparticles, which are packed in a microfluidic structure3. Therefore, when an external magnet approaches, a complex interaction is created within the magnetized porous medium between the magnetic and flux forces. The magnetic force acting on the nanoparticles is strong enough to capture them and resist flow drag3,4,7. This approach requires microfabrication techniques that achieve resolutions in the order of a few micrometers to generate micrometric structures that retain the microparticles.
Current microfabrication techniques allow the high-resolution fabrication of structures from a few microns to hundreds of nanometers8. However, many of these techniques require specialized, expensive, or complicated equipment. One of the main difficulties is the requirement for a cleanroom for mold fabrication, which remains costly and time-consuming8,9. Recently, microfluidic engineers have overcome this drawback by developing a variety of alternative fabrication methods, with various advantages such as reduced costs, faster turnaround times, cheaper materials and tools, and increased functionality8. In this way, the development of new microfabrication techniques brought low-cost, non-cleanroom methods that achieve resolutions as low as 10 &#181;m8. Patterning can be used directly on a substrate without generating an expensive molding pattern, thus avoiding a time-consuming process. Direct fabrication methods include CNC milling, laser ablation, and direct lithography8. All these methods are suitable for producing high-aspect-ratio channels in a wide range of materials, regardless of their hardness9, enabling new and advantageous geometries, physical behaviors, and qualities in microfluidic devices8.
CNC micromilling creates microscale structures using cutting tools that remove bulk material from a substrate and is an effective fabrication method for microfluidic devices10,11. The micromilling technique can be useful in microfluidic applications to create microchannels and features directly on the work surface, offering a key advantage: a workpiece can be fabricated in a short time (less than 30 min), significantly reducing the turnaround time from design to prototype12. In addition, the wide availability of cutting accessories of different materials, sizes, and shapes makes CNC milling machines a suitable tool that has allowed the fabrication of different features in many types of low-cost disposable materials13.
Among all the materials commonly used in micromilling, thermoplastics remain a leading choice due to their many favorable properties and compatibility with biological applications10,14. Thermoplastics are an attractive substrate for microfluidic systems due to their significant advantages for developing low-cost, disposable analytical systems9. In addition, these materials are highly amenable to high-volume manufacturing processes, making them suitable for commercialization and mass production. For these reasons, thermoplastics such as PMMA have been considered reliable and robust materials since the early years of microfluidics10. Different protocols have been described to fabricate closed channels in thermoplastics, such as solvent bonding15, heat bonding16, and ultraviolet (UV)/ozone surface treatment bonding17.
In many cases, the positioning resolution achieved with conventional micromilling machines is not sufficient for some microfluidic applications that require structures smaller than 10 &#181;m. High-end micromilling has enough resolution. Unfortunately, due to high prices, its use is limited to a handful of users12. Previously, our research group reported the fabrication and manipulation of a low-cost tool that allows machining structures of less than 10 &#181;m, overcoming the resolution of conventional milling machines12. The fixture is a platform manufactured by 3D printing with simple electronics, containing three piezoelectric actuators. The surface contains hinge-shaped joints that allow it to be lifted when the piezoelectric elements act simultaneously. Z-axis displacement can be controlled with a resolution of 500 nm and an accuracy of &#177;1.5 &#181;m12.
This paper presents the steps of the manufacturing process of an acrylic device (PMMA) through a micromilling technique. The chip design consists of a main channel 200 &#181;m wide and 200 &#181;m high and a side channel with the same dimensions to purge the flow of the reagents. In the central region, the channel is interrupted by a physical restriction of only 5 &#181;m in height, fabricated with the 3D-printed piezoelectric platform made by this group12, to capture magnetic microparticles that make up a magnetic trap for nanoparticles by placing an external magnet. We show the operation of the microfluidic device by performing an immunoassay to detect a commercial antibody using lysozyme as a model antigen conjugated to 100 nm magnetic nanoparticles. This device combines different features that make it unique4: the use of magnetic nanoparticles as immune support reduces the total test time from hours to minutes; using a fluorogenic enzyme for detection allows for limits of detection that are comparable to those of standard enzyme-linked immunosorbent assays (ELISAs); and the use of a thermoplastic as a fabrication material makes it compatible with mass production, which was not the case for previous microfluidic nanoparticles&#39; magnetic traps3, and makes it an excellent candidate to develop POCT.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.008 Endmill</td>
			<td>KYOCERA SGS&#160;</td>
			<td>2204</td>
			<td>2FL 0.008x1/8x0.12x1-1/12</td>
		</tr>
		<tr>
			<td>0.032 Endmill</td>
			<td>KYOCERA SGS&#160;</td>
			<td>2228</td>
			<td>2FL 0.032x1/8x0.48x1-1/12</td>
		</tr>
		<tr>
			<td>Carbonyl-iron microparticles&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>44890</td>
			<td>7 &#956;m&#160;</td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Fermont</td>
			<td>6201</td>
			<td>Health Hazard: Moderate 
			Flammability: None 
			Reactivity: None 
			Contact Hazard: Moderate&#160;</td>
		</tr>
		<tr>
			<td>CMOS camera Moment</td>
			<td>Teledyne Photometrics</td>
			<td></td>
			<td>Sensor Technology: CMOS 
			Quantum Efficiency: 73% 
			Pixel Size: 4.5 &#181;m x 4.5 &#181;m 
			Supported Interfaces: USB 3.2 Gen 2</td>
		</tr>
		<tr>
			<td>Dr Engrave Software</td>
			<td>Roland DGA Corporation</td>
			<td></td>
			<td>Engraving software to design and create the engraving path on the surface</td>
		</tr>
		<tr>
			<td>Extraction hood</td>
			<td>Unknown</td>
			<td>Unknown</td>
			<td></td>
		</tr>
		<tr>
			<td>Flexible Plastic Tubing</td>
			<td>Tygon</td>
			<td>AAD04103</td>
			<td>ID = 0.020, OD = 0.060</td>
		</tr>
		<tr>
			<td>Fluorescence microsope&#160;</td>
			<td>ZEISS</td>
			<td>Axio Vert.A1</td>
			<td></td>
		</tr>
		<tr>
			<td>High Precision Dispense Needle</td>
			<td>Loctite</td>
			<td>98612</td>
			<td></td>
		</tr>
		<tr>
			<td>Homemade piezoelectric controller application</td>
			<td>LabView&#160;</td>
			<td></td>
			<td>See reference 12 for more details.</td>
		</tr>
		<tr>
			<td>Loctite 495 instant adhesive</td>
			<td>Henkel</td>
			<td>49503</td>
			<td>Apply with micropipette tip or dispensing needle&#160;</td>
		</tr>
		<tr>
			<td>MagJET Separation Rack</td>
			<td>thermoscientific</td>
			<td></td>
			<td>12 x 1.5 mL</td>
		</tr>
		<tr>
			<td>Mechanic press</td>
			<td>Home-made</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Milling Machine</td>
			<td>Roland</td>
			<td>MDX-50</td>
			<td></td>
		</tr>
		<tr>
			<td>Piezoelectric platform&#160;</td>
			<td>Home-made</td>
			<td></td>
			<td>See reference 12</td>
		</tr>
		<tr>
			<td>Polymethylmethacrylate - Sheet - PMMA, Acrylic</td>
			<td>Goodfellow</td>
			<td>ME303018/1</td>
			<td>Thickness: 1.3 mm, Transparency: Clear/Transparent</td>
		</tr>
		<tr>
			<td>PVCamTest software</td>
			<td>Teledyne Photometrics</td>
			<td>Version 3.10.107&#160;</td>
			<td>Image acquisition software</td>
		</tr>
		<tr>
			<td>Stereo microscope</td>
			<td>Nikon</td>
			<td>SMZ 7457</td>
			<td></td>
		</tr>
		<tr>
			<td>SuperMag Carboxyl Beads</td>
			<td>Ocean NanoTech</td>
			<td>KSC0100</td>
			<td>100 nm</td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>kd Scientific</td>
			<td>&#160;KDS200</td>
			<td>Can hold up to two syringes</td>
		</tr>
		<tr>
			<td>Utrasonic bath</td>
			<td>Branson</td>
			<td>2800</td>
			<td></td>
		</tr>
		<tr>
			<td>VPanel software&#160;</td>
			<td>Windows OS</td>
			<td>Version 1.0.3.0</td>
			<td>Software for controlling the micromilling machine</td>
		</tr>
	</tbody>
</table>

computer numerical control micromilling of a microfluidic acrylic device with a staggered restriction for magnetic nanoparticle-based immunoassays

Microfluidic systems have greatly improved immunoassay techniques. However, many microfabrication techniques require specialized, expensive, or complicated equipment, making fabrication costly and incompatible with mass production, which is one of the most important preconditions for point-of-care tests (POCT) to be adopted in low-resource settings. This work describes the fabrication process of an acrylic (polymethylmethacrylate, PMMA) device for nanoparticle-conjugated enzymatic immunoassay testing using the computer numerical control (CNC) micromilling technique. The functioning of the microfluidic device is shown by performing an immunoassay to detect a commercial antibody using lysozyme as a model antigen conjugated to 100 nm magnetic nanoparticles. This device integrates a physical staggered restriction of only 5 &#181;m in height, used to capture magnetic microparticles that make up a magnetic trap by placing an external magnet. In this way, the magnetic force on the immunosupport of conjugated nanoparticles is enough to capture them and resist flow drag. This microfluidic device is particularly suitable for low-cost mass production without the loss of precision for immunoassay performance.

It was possible to establish a highly reproducible fabrication protocol that improves the resolution of the conventional micromilling technique. Using this protocol, the fabrication of a channel as small as 5 &#181;m in height that operates as a staggered restriction in a 200 &#181;m high channel is achieved. The simple design of the staggered restriction captures iron microparticles of 7.5 &#181;m diameter which, when compacted in the microchannel, allow the creation of a magnetic trap when an external magnet approaches...

Watch this Scientific Journal Video about Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-Based Immunoassays at JoVE.com

Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-Based Immunoassays

Microfluidics is a powerful tool for the development of diagnostic tests. However, expensive equipment and materials, as well as laborious fabrication and handling techniques, are often required. Here, we detail the fabrication protocol of an acrylic microfluidic device for magnetic micro- and nanoparticle-based immunoassays in a low-cost and simple-to-use setting.

Microfluidic systems have greatly improved immunoassay techniques. However, many microfabrication techniques require specialized, expensive, or ...

computer-numerical-control-micromilling-microfluidic-acrylic-device

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

2.0K Views.  Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav). Microfluidics is a powerful tool for the development of diagnostic tests. However, expensive equipment and materials, as well as laborious fabrication and handling techniques, are often required. Here, we detail the fabrication protocol of an acrylic microfluidic device for magnetic micro- and nanoparticle-based immunoassays in a low-cost and simple-to-use setting.

Video: Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-Based Immunoassays

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic samples with a wide range of possible sensor designs such as interferometers and resonators 1,2. Most of the existing RI sensing applications focus on biological materials in aqueous solutions in visible and IR frequencies, such as DNA hybridization and genome sequencing. At terahertz frequencies, applications include quality control, monitoring of industrial processes and sensing and detection applications involving nonpolar materials.
Several potential designs for refractive index sensors in the terahertz regime exist, including photonic crystal waveguides 3, asymmetric split-ring resonators 4, and photonic band gap structures integrated into parallel-plate waveguides 5. Many of these designs are based on optical resonators such as rings or cavities. The resonant frequencies of these structures are dependent on the refractive index of the material in or around the resonator. By monitoring the shifts in resonant frequency the refractive index of a sample can be accurately measured and this in turn can be used to identify a material, monitor contamination or dilution, etc.
The sensor design we use here is based on a simple parallel-plate waveguide 6,7. A rectangular groove machined into one face acts as a resonant cavity (Figures 1 and 2). When terahertz radiation is coupled into the waveguide and propagates in the lowest-order transverse-electric (TE1) mode, the result is a single strong resonant feature with a tunable resonant frequency that is dependent on the geometry of the groove 6,8. This groove can be filled with nonpolar liquid microfluidic samples which cause a shift in the observed resonant frequency that depends on the amount of liquid in the groove and its refractive index 9.
Our technique has an advantage over other terahertz techniques in its simplicity, both in fabrication and implementation, since the procedure can be accomplished with standard laboratory equipment without the need for a clean room or any special fabrication or experimental techniques. It can also be easily expanded to multichannel operation by the incorporation of multiple grooves 10. In this video we will describe our complete experimental procedure, from the design of the sensor to the data analysis and determination of the sample refractive index.

The procedure for implementing a refractive index sensor for terahertz frequencies based on a grooved parallel-plate waveguide geometry is described here. The method yields a measurement of the refractive index of a small volume of liquid through monitoring of the shift in the resonant frequency of the waveguide structure

Refractive index (RI) sensing is a powerful noninvasive and label-free sensing technique for the identification, detection and monitoring of microfluidic ...

Implementation of a Reference Interferometer for Nanodetection

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing its free spectral range (FSR), the module is put in parallel with a fiber taper-microcavity system and then calibrated through isolating and eliminating random shifts in the laser frequency (i.e. laser jitter noise). To realize the taper-microcavity junction and to maximize the optical power that is transferred to the resonator, a single-mode optical fiber waveguide is pulled. Solutions containing polystyrene nanobeads are then prepared and flown to the microcavity in order to demonstrate the system&#8217;s ability to sense binding to the surface of the microcavity. Data is post-processed via adaptive curve fitting, which allows for high-resolution measurements of the quality factor as well as the plotting of time-dependent parameters, such as resonant wavelength and split frequency shifts. By carefully inspecting steps in the time-domain response and shifting in the frequency-domain response, this instrument can quantify discrete binding events.

A reference interferometer technique, which is designed to remove undesirable laser jitter noise for nanodetection, is utilized for probing an ultra-high quality factor microcavity. Instructions for assembly, setup, and data acquisition are provided, alongside the measurement process for specifying the cavity quality factor.

A thermally and mechanically stabilized fiber interferometer suited for examining ultra-high quality factor microcavities is fashioned. After assessing ...

SSVEP-based Experimental Procedure for Brain-Robot Interaction with Humanoid Robots

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in helping the disabled in their daily lives. The overall goal of our method is to establish an SSVEP-based experimental procedure by integrating multiple software programs, such as OpenViBE, Choregraph, and Central software as well as user developed programs written in C++ and MATLAB, to enable the study of brain-robot interaction with humanoid robots.
This is achieved by first placing EEG electrodes on a human subject to measure the brain responses through an EEG data acquisition system. A user interface is used to elicit SSVEP responses and to display video feedback in the closed-loop control experiments. The second step is to record the EEG signals of first-time subjects, to analyze their SSVEP features offline, and to train the classifier for each subject. Next, the Online Signal Processor and the Robot Controller are configured for the online control of a humanoid robot. As the final step, the subject completes three specific closed-loop control experiments within different environments to evaluate the brain-robot interaction performance.
The advantage of this approach is its reliability and flexibility because it is developed by integrating multiple software programs. The results show that using this approach, the subject is capable of interacting with the humanoid robot via brain signals. This allows the mind-controlled humanoid robot to perform typical tasks that are popular in robotic research and are helpful in assisting the disabled.

The overall goal of this method is to establish an SSVEP-based experimental procedure by integrating multiple software programs to enable the study of brain-robot interaction with humanoid robots, which is prospective in assisting the sick and elderly as well as performing unsanitary or dangerous jobs.

Brain-Robot Interaction (BRI), which provides an innovative communication pathway between human and a robotic device via brain signals, is prospective in ...

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. However, the responsiveness of a galvanometer mirror is limited by its inertia; hence, the gain of a galvanometer mirror is reduced when the control path is steep. In this research, we propose a method to extend the corresponding frequency using a pre-emphasis technique to compensate for the gain reduction of galvanometer mirrors in sine-wave path tracking using proportional-integral-differential (PID) control. The pre-emphasis technique obtains an input value for a desired output value in advance. Applying this method to control the galvanometer mirror, the raw gain of a galvanometer mirror in each frequency and amplitude for sine-wave path tracking using a PID controller was calculated. Where PID control is not effective, maintaining a gain of 0 dB to improve the trajectory tracking accuracy, it is possible to expand the speed range in which a gain of 0 dB can be obtained without tuning the PID control parameters. However, if there is only one frequency, amplification is possible with a single pre-emphasis coefficient. Therefore, a sine wave is suitable for this technique, unlike triangular and sawtooth waves. Hence, we can adopt a pre-emphasis technique to configure the parameters in advance, and we need not prepare additional active control models and hardware. The parameters are updated immediately within the next cycle because of the open loop after the pre-emphasis coefficients are set. In other words, to regard the controller as a black box, we need to know only the input-to-output ratio, and detailed modeling is not required. This simplicity allows our system to be easily embedded in applications. Our method using the pre-emphasis technique for a motion-blur compensation system and the experiment conducted to evaluate the method are explained.

We propose a method to extend the corresponding frequency by using a pre-emphasis technique. This method compensates for the gain reduction of a galvanometer mirror in sine-wave path tracking using proportional-integral-differential control.

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

A Silicon-tipped Fiber-optic Sensing Platform with High Resolution and Fast Response

In this article, we introduce an innovative and practically promising fiber-optic sensing platform (FOSP) that we proposed and demonstrated recently. This FOSP relies on a silicon Fabry-Perot interferometer (FPI) attached to the fiber end, referred to as Si-FOSP in this work. The Si-FOSP generates an interferogram determined by the optical path length (OPL) of the silicon cavity. Measurand alters the OPL and thus shifts the interferogram. Due to the unique optical and thermal properties of the silicon material, this Si-FOSP exhibits an advantageous performance in terms of sensitivity and speed. Furthermore, the mature silicon fabrication industry endows the Si-FOSP with excellent reproducibility and low cost toward practical applications. Depending on the specific applications, either a low-finesse or high-finesse version will be utilized, and two different data demodulation methods will be adopted accordingly. Detailed protocols for fabricating both versions of the Si-FOSP will be provided. Three representative applications and their according results will be shown. The first one is a prototype underwater thermometer for profiling the ocean thermoclines, the second one is a flow meter to measure flow speed in the ocean, and the last one is a bolometer used for monitoring exhaust radiation from magnetically confined high-temperature plasma.

This work reports an innovative silicon-tipped fiber-optic sensing platform (Si-FOSP) for high-resolution and fast-response measurement of a variety of physical parameters, such as temperature, flow, and radiation. Applications of this Si-FOSP span from oceanographic research, mechanical industry, to fusion energy research.

In this article, we introduce an innovative and practically promising fiber-optic sensing platform (FOSP) that we proposed and demonstrated recently. This ...

Production of a Strain-Measuring Device with an Improved 3D Printer

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in the analog electrical signal in a traditional strain gauge operation, a new strain measurement method is presented here. It uses a photographic technique to display the strain change by amplifying the change of the pointer displacement of the mechanism. A visual polydimethylsiloxane (PDMS) lens with a focal length of 7.16 mm was added to a smartphone camera to generate a lens group acting as a microscope to capture images. It had an equivalent focal length of 5.74 mm. Acrylonitrile butadiene styrene (ABS) and nylon amplifiers were used to test the influence of different materials on the sensor performance. The production of the amplifiers and PDMS lens is based on improved 3D printing technology. The data obtained were compared with the results from finite element analysis (FEA) to verify their validity. The sensitivity of the ABS amplifier was 36.03 &plusmn; 1.34 &#181;&epsilon;/&#181;m, and the sensitivity of the nylon amplifier was 36.55 &plusmn; 0.53 &#181;&epsilon;/&#181;m.

This work presents a strain measurement sensor consisting of an amplification mechanism and a polydimethylsiloxane microscope manufactured using an improved 3D printer.

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in ...

Pneumatically Driven Microfluidic Platform for Micro-Particle Concentration

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. This platform has a three-dimensional (3D) network with curved fluid channels and three pneumatic valves, which create networks, channels, and spaces through duplex replication with polydimethylsiloxane (PDMS). The device operates based on the transient response of a fluid flow rate controlled by a pneumatic valve in the following order: (1) sample loading, (2) sample blocking, (3) sample concentration, and (4) sample release. The particles are blocked by thin diaphragm layer deformation of the sieve valve (Vs) plate and accumulate in the curved microfluidic channel. The working fluid is discharged by the actuation of two on/off valves. As a result of the operation, all particles of various magnifications were successfully intercepted and disengaged. When this technology is applied, the operating pressure, the time required for concentration, and the concentration rate may vary depending on the device dimensions and particle size magnification.

The present protocol describes a pneumatic microfluidic platform that can be used for efficient microparticle concentration.

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. ...