The authors have no acknowledgements.

1. Acquisition of Gain Data for a Galvanometer Mirror
<ol>
	<li>Fix the galvanometer mirror such that it is stabilized to protect it from damage while oscillating. Not only the galvanometer mirror, but also the body of the galvanometer mirror, moves if not fixed in place using a custom-made metal jig with a circular hole for the galvanometer mirror. Fix the jig onto an optical carrier and an optical bench.</li>
	<li>Connect BNC cables from the AD/DA board through a terminal block to the input and position sockets in the servo driver of the galvanometer mirror.</li>
	<li>Program the sine-wave function generator as a graphical user interface (GUI) using the SDK of the AD/DA board with C++, which is able to set an arbitrary frequency, amplitude, and duration, as shown in Figure 3. 
	NOTE: This customized function generator contributes to cutting the temporal cost for continuous trials in step 1.5, since the trial is conducted many times.</li>
	<li>Set the frequency to vary from 100 Hz to 500 Hz in 100-Hz intervals, and set the amplitude to vary from 10 mV to 500 mV in 10-mV intervals in the GUI. Overall, 250 combinations exist. To test 250 combinations, a double loop is efficient to implement. The first loop is for frequencies from 100 Hz to 500 Hz, which is implemented 50 times. The second loop is for amplitudes from 10 mV to 500 mV, which is implemented for 50 times.</li>
	<li>Add the sine-wave path signal into the AD/DA board for 2,000 samplings as duration in the GUI. Simultaneously record the position signal of the galvanometer mirror to read the analogue value of the AD/DA board. In C++ coding using a library of AD/DA board, use the same thread for writing and reading in programming. Calculate the current angle of galvanometer mirror &#952; (writing information) by this equation 
	<img alt="Equation 2" src="/files/ftp_upload/55431/55431eq2.jpg" /> 
	where t is time, <img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" /> is amplitude, &#402; is frequency.</li>
	<li>Save the position signal data as a .csv file and include the value of the frequency and amplitude in its filename.</li>
	<li>Repeat steps 1.4 - 1.6 for 250 iterations.</li>
</ol>
2. Calculation to Get Pre-emphasis Coefficients
<ol>
	<li>Apply a median filter for the csv files (recorded signals) to avoid noise effects. The spatial size of the median filter is 5.</li>
	<li>Run the script to calculate the peak-to-peak value (corresponding with the amplitude multiplied by 2), using MATLAB for each of the csv files, as shown in Figure 4 (the graph represents the data of the sine-wave path).</li>
	<li>Plot the peak-to-peak data on a graph to determine the linearity at each frequency, and limit the usage region of the input amplitude when the plots are nonlinear, as shown in Figure 5. 
	NOTE: The nonlinear part of the graph represents saturation of the PID control; hence, it is advisable to avoid using them to secure the limitation of specification of control.</li>
	<li>Execute linear regression for peak-to-peak data in a spreadsheet to obtain the linear interpolation coefficients of each frequency. In this process, five sets of slopes and intercepts are obtained. They correspond with the frequencies from 100 Hz to 500 Hz at each 100 Hz. An approximation of the straight line of 300 Hz is displayed in Figure 5(A), and the linear interpolation coefficients of each frequency are shown in Table 1.</li>
	<li>Using quadratic multiple linear regression, execute quartic interpolation to obtain the quartic interpolation coefficients (pre-emphasis coefficients) in the spreadsheet for the linear interpolation coefficients of each frequency. The pre-emphasis coefficients are shown in Table 2. 
	NOTE: In this research, the linear interpolation coefficients vary in the form of a quadratic curve; however, other types of functions, such as quadratic and cubic equations, are applied if the error is minimal.</li>
</ol>
3. Online Signal Amplification Based on the Pre-emphasis Technique
<ol>
	<li>Execute the software that calculates the updated input amplitude value <img alt="Equation 5" src="/files/ftp_upload/55431/55431eq5.jpg" /> from the ideal input amplitude value <img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" /> and the frequency&#160;&#402; using the pre-emphasis coefficients.
	<ol>
		<li>Save the pre-emphasis coefficients as constant values in the C++ software. When the device is updated, these constant values are also updated.</li>
		<li>Program a function 
		<img alt="Equation 7" src="/files/ftp_upload/55431/55431eq7.jpg" /> 
		in the C++ software and obtain the linear interpolation coefficients. Substitute them for ai, bi, ci, di, and ei from the equation and Table 2.</li>
		<li>Program a function 
		<img alt="Equation 13" src="/files/ftp_upload/55431/55431eq13.jpg" /> 
		in the C++ software and obtain an updated input amplitude value <img alt="Equation 5" src="/files/ftp_upload/55431/55431eq5.jpg" /> to substitute for <img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" /> and the linear interpolation coefficients that were obtained in step 3.1.2.</li>
	</ol>
	</li>
	<li>Repeat steps 1.4 - 1.6 for arbitrary times with <img alt="Equation 5" src="/files/ftp_upload/55431/55431eq5.jpg" /> using the pre-emphasis technique in the GUI.NOTE: To avoid saturation of the region of PID control, set 400 mV for up to 200 Hz, 200 mV for up to 300 Hz, 100 mV for up to 400 Hz, and 50 mV for up to 500 Hz.</li>
	<li>Repeat step 2.2 and plot peak-to-peak data as a graph to view the improvement in the gain.</li>
</ol>
4. Experiment on Motion-blur Compensation
<ol>
	<li>Prepare a conveyor belt that can move at 30 km/h using a belt that can adhere to sticky textures. The custom-made conveyor belt is composed with a speed-control motor, an iron rubber belt, and so on. It can be replaced with ready-made conveyor belt which can control speed.</li>
	<li>Print a fine-texture pattern onto printable tape and paste it onto the conveyor belt. 
	NOTE: The pasted texture is shown in Figure 6. The stripes are programmed using a library &#34;ofxPDF&#34; in openFrameworks, and the photographic image is from a stock photo company.</li>
	<li>Set up optical devices such as a camera, a lens, and an illumination, as shown in Figure 2. Place the galvanometer mirror in front of the lens which is connected to the camera, and place the illumination to illuminate the conveyor belt.
	<ol>
		<li>Set the camera frequency to 333 Hz, the exposure time to 1 ms, and the number of pixels to 848 * 960 (width * height).</li>
	</ol>
	</li>
	<li>Synchronize the rotational timing of the galvanometer mirror and the exposure time of the camera. In the software, when the angle of the galvanometer mirror arrives the position where to start exposure, the program sends a software trigger into the camera. The timing of software trigger is illustrated in Figure 7.</li>
	<li>Input the speed of the conveyor belt vt (30 km/h) and the distance from the camera to the conveyor belt L(3.0 m) to calculate required angular velocity &#969;r of the galvanometer mirror in the GUI as in Figure 8.&#160;&#969;r is calculated as follows: 
	<img alt="Equation 18" src="/files/ftp_upload/55431/55431eq18.jpg" /></li>
	<li>Input the frequency &#402;(330.0 Hz) in the GUI as in Figure 8 to calculate original input amplitude <img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" />. Calculate&#160;<img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" /> as follows: 
	<img alt="Equation 19" src="/files/ftp_upload/55431/55431eq19.jpg" /></li>
	<li>Copy and paste <img alt="Equation 3" src="/files/ftp_upload/55431/55431eq3.jpg" /> into the source code, and rotate the galvanometer with the pre-emphasized control value&#160;&#952; for the galvanometer servo driver as follows: 
	<img alt="Equation 20" src="/files/ftp_upload/55431/55431eq20.jpg" /> 
	where t is time. Figure 7 illustrates how&#160;&#952; is calculated from A.</li>
	<li>Record images when the conveyor belt is moving at vt (30 km/h). 
	NOTE: Figure 9 illustrates the motion of the conveyor belt.</li>
</ol>

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The authors have nothing to disclose.

This article presents a procedure capable of expanding the sine-wave frequency range to achieve high-accuracy trajectory tracking with PID control. Because the responsiveness of a galvanometer mirror is limited by its inertia, it is critical to use a galvanometer mirror when the control path is steep. However, in this research, we propose a method to improve the specification of control and then prove the method by obtaining experimental results.
In our procedure, step 2.5 is the most critical...

Various optical actuators and control methods suitable for various optical applications have been proposed and developed1,2. These optical actuators are able to control the optical path; galvanometer mirrors especially offer a good balance in terms of accuracy, speed, mobility, and cost3,4,5. Actually, the advantage offered by the speed and accuracy of galvanometer mirrors has led to the realization of a variety of optical applications, such as target tracking and drawing, scanning control, and motion-blur compensation6,7,8,9,10,11,12. However, in our previous motion-blur compensation system, a galvanometer mirror using a proportional-integral-differential (PID) controller provided a small gain; hence, it was difficult to achieve a higher frequency and a faster speed11.
On the other hand, PID control is a widely-used method, as it satisfies a certain level of tracking accuracy13. A variety of methods have been proposed to correct the gain in PID control. As a typical solution, PID control parameter tuning is conducted manually. However, it takes time and special skill to maintain. A more sophisticated method, an auto-tuning function to automatically determine the parameters, has been proposed and is widely used14. The tracking accuracy for high-speed operations is improved using the auto-tuning function when the proportional gain value P increases. However, this also increases the convergence time and noise in the low-speed range. Hence, the tracking accuracy is not necessarily improved. Although a self-tuning controller can be tuned to set suitable parameters for PID control, the tuning introduces a delay because of the need to obtain suitable parameters; therefore, it is difficult to adopt this method in real-time applications15. An extended PID controller16,17 and an extended predictive controller18 have been proposed to extend general PID control and to enhance the tracking performance of galvanometer mirrors for a variety of tracking paths, such as triangular waves, sawtooth waves, and sine waves. However, in those systems, the galvanometer system was regarded as a black box, whereas a model of the control system was required, and the control system was not regarded as a black box. Hence, those methods require that their model for each galvanometer mirror be updated. Moreover, although Mnerie et al. validated their method of focusing on a detailed output wave and phase, their research did not include the attenuation of the entire wave. In fact, in our previous research11, the gain was significantly decreased when the sinusoidal frequency was high, thereby indicating the necessity to compensate for the gain of the entire wave.
In this research, our procedure for gain compensation with PID control12 is based on the pre-emphasis technique19,20,21&#8212;a method to enhance the quality or speed of communication in communications engineering&#8212;which enables the construction of an experimental system using existing equipment. Figure 1 shows the flow structure. The pre-emphasis technique is able to obtain in advance the desired output value from an input value, where PID control is not effective, even if the galvanometer mirror and its controller are regarded as black boxes. This enables them to expand the frequency and amplitude range in which a gain of 0 dB can be obtained without tuning the PID control parameters.
When the gain is amplified, the response characteristics of the galvanometer mirror generally differ at different frequencies, and therefore, we need to amplify each frequency with amplification coefficients. Thus, a sine wave is suitable for the pre-emphasis technique, as there is only one frequency in each sine wave. In this research, because we apply gain compensation to accomplish motion-blur compensation, the control signal is limited to sine-wave scanning, and the sine-wave signal constitutes a single frequency, unlike other waves, such as triangular and sawtooth waves. Further, the input signal into the galvanometer mirror is updated immediately within the next cycle because of the open loop after the pre-emphasis coefficients are set. In other words, we need to know only the input-to-output ratio to regard the controller as a black box, and detailed modeling is not required. This simplicity allows our system to be easily embedded in applications.
The overall goal of this method is to establish an experimental procedure of motion-blur compensation as an application by gain compensation using the pre-emphasis technique. Multiple hardware devices are used in these procedures, such as a galvanometer mirror, a camera, a conveyor belt, illumination, and a lens. Central software user-developed programs written in C++ also constitute part of the system. Figure 2 shows a schematic of the experimental setup. The galvanometer mirror rotates with gain-compensated angular velocity, thereby making it possible to evaluate the amount of blur from the images.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Galvanometer mirror</td>
			<td style="width:71px;">GSI</td>
			<td style="width:119px;">M3s X axis</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Custom-made metal jig</td>
			<td style="width:71px;">ASKK</td>
			<td style="width:119px;">-</td>
			<td>With circular hole for galvanometer mirror</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Optical carrier</td>
			<td style="width:71px;">SIGMAKOKI</td>
			<td style="width:119px;">CAA-60L</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Optical bench</td>
			<td style="width:71px;">SIGMAKOKI</td>
			<td style="width:119px;">OBT-1500LH</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Oscilloscope</td>
			<td style="width:71px;">Tektronix</td>
			<td style="width:119px;">MSO 4054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">AD/DA board</td>
			<td style="width:71px;">Interface</td>
			<td style="width:119px;">PCI-361216</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PC</td>
			<td style="width:71px;">DELL</td>
			<td style="width:119px;">Precision T3600</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Galvanometer mirror servo controller</td>
			<td style="width:71px;">GSI</td>
			<td style="width:119px;">Minisax</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Lens</td>
			<td style="width:71px;">Nikkor</td>
			<td style="width:119px;">AF-S NIKKOR 200mm f/2G ED VR II&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">High-speed camera</td>
			<td style="width:71px;">Mikrotron</td>
			<td style="width:119px;">Eosens MC4083</td>
			<td>Discontinued, but sold as MC4087. The cable connection is different from MC4083</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Conveyor belt</td>
			<td style="width:71px;">ASUKA</td>
			<td style="width:119px;">-</td>
			<td>With a speed-control motor(BX5120A-A made by Oriental Motor), iron rubber belt(100-F20-800A-J made by NOK), and so on</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Printable tape</td>
			<td style="width:71px;">A-one</td>
			<td style="width:119px;">F20A4-6</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Photographic texture</td>
			<td style="width:71px;">Shutterstock, Inc.</td>
			<td align="right" style="width:119px;">231357754</td>
			<td>Printed computer motherboard with microcircuit, close up</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Terminal block</td>
			<td style="width:71px;">Interface</td>
			<td style="width:119px;">TNS-6851B</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">CoaXPress board</td>
			<td style="width:71px;">AVALDATA</td>
			<td style="width:119px;">APX-3664</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">MATLAB</td>
			<td style="width:71px;">mathworks</td>
			<td style="width:119px;">MATLAB R2015a</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

The results presented here were obtained using an AD/DA board and a camera. Figure 1 shows the procedure of the pre-emphasis technique; therefore, it is the core of this article. It is unnecessary to set the parameters of the PID control after the initialization state; hence, the online process is significantly simple.
Figure 10 shows the results obtained by applying the pre-emphasis technique t...

Watch this Scientific Journal Video about Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques at Jo

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

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. ...

gain-compensation-methodology-for-sinusoidal-scan-galvanometer-mirror

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8.5K vistas.  University of Tokyo.  Proponemos un método para extender la frecuencia correspondiente mediante el uso de una técnica de pre-énfasis. Este método compensa la reducción de ganancia de un galvanómetro de espejo en la trayectoria de onda senoidal de seguimiento utilizando el control-integral-diferencial proporcional. 

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

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards understanding its mechanism. Protonation and conformational changes affect the vibration pattern of amino acid side chains and of the peptide bond, respectively, both of which can be probed by infrared (IR) difference spectroscopy. For proteins whose function can be repetitively and reproducibly triggered by light, it is possible to obtain infrared difference spectra with (sub)microsecond resolution over a broad spectral range using the step-scan Fourier transform infrared technique. With ~102-103 repetitions of the photoreaction, the minimum number to complete a scan at reasonable spectral resolution and bandwidth, the noise level in the absorption difference spectra can be as low as ~10-4, sufficient to follow the kinetics of protonation changes from a single amino acid. Lower noise levels can be accomplished by more data averaging and/or mathematical processing. The amount of protein required for optimal results is between 5-100 &#181;g, depending on the sampling technique used. Regarding additional requirements, the protein needs to be first concentrated in a low ionic strength buffer and then dried to form a film. The protein film is hydrated prior to the experiment, either with little droplets of water or under controlled atmospheric humidity. The attained hydration level (g of water / g of protein) is gauged from an IR absorption spectrum. To showcase the technique, we studied the photocycle of the light-driven proton-pump bacteriorhodopsin in its native purple membrane environment, and of the light-gated ion channel channelrhodopsin-2 solubilized in detergent.

Key steps of protein function, in particular backbone conformational changes and proton transfer reactions, often take place in the microsecond to millisecond time scale. These dynamical processes can be studied by time-resolved step-scan Fourier-transform infrared spectroscopy, in particular for proteins whose function is triggered by light.

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Free-form Light Actuators &amp;#8212; Fabrication and Control of Actuation in Microscopic Scale

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

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 ...

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape method or individual WS2 nanotubes by dispersing the suspension of WS2 nanotubes. The selected samples have been fabricated into devices by the use of the electron beam lithography and electrolyte is put on the devices. We have characterized the electronic properties of the devices under applying the gate voltage. In the small gate voltage region, ions in the electrolyte are accumulated on the surface of the samples which leads to the large electric potential drop and resultant electrostatic carrier doping at the interface. Ambipolar transfer curve has been observed in this electrostatic doping region. When the gate voltage is further increased, we met another drastic increase of source-drain current which implies that ions are intercalated into layers of WS2 and electrochemical carrier doping is realized. In such electrochemical doping region, superconductivity has been observed. The focused technique provides a powerful strategy for achieving the electric-filed-induced quantum phase transition.

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Here, we present a protocol to control the carrier number in solids by using the electrolyte.

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a result, these platforms have not been fully exploited for direct observation of high-pressure transport in fractures. This work introduces microfluidic platforms that enable direct observation of multiphase flow in devices featuring surrogate permeable media and fractured systems. Such platforms provide a pathway to address important and timely questions such as those related to CO2 capture, utilization and storage. This work provides a detailed description of the fabrication techniques and an experimental setup that may serve to analyze the behavior of supercritical CO2 (scCO2) foam, its structure and stability. Such studies provide important insights regarding enhanced oil recovery processes and the role of hydraulic fractures in resource recovery from unconventional reservoirs. This work presents a comparative study of microfluidic devices developed using two different techniques: photolithography/wet-etching/thermal-bonding versus Selective Laser-induced Etching. Both techniques result in devices that are chemically and physically resistant and tolerant of high pressure and temperature conditions that correspond to subsurface systems of interest. Both techniques provide pathways to high-precision etched microchannels and capable lab-on-chip devices. Photolithography/wet-etching, however, enables fabrication of complex channel networks with complex geometries, which would be a challenging task for laser etching techniques. This work summarizes a step-by-step photolithography, wet-etching and glass thermal-bonding protocol and, presents representative observations of foam transport with relevance to oil recovery from unconventional tight and shale formations. Finally, this work describes the use of a high-resolution monochromatic sensor to observe scCO2 foam behavior where the entirety of the permeable medium is observed simultaneously while preserving the resolution needed to resolve features as small as 10 &#181;m.

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

This paper describes a protocol along with a comparative study of two microfluidic fabrication techniques, namely photolithography/wet-etching/thermal-bonding and Selective Laser-induced Etching (SLE), that are suitable for high-pressure conditions. These techniques constitute enabling platforms for direct observation of fluid flow in surrogate permeable media and fractured systems under reservoir conditions.

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a ...

Manufacturing, Control, and Performance Evaluation of a Gecko-Inspired Soft Robot

This protocol presents a method for manufacturing, control, and evaluation of the performance of a soft robot that can climb inclined flat surfaces with slopes of up to 84&#176;. The manufacturing method is valid for the fast pneunet bending actuators in general and might, therefore, be interesting for newcomers to the field of actuator manufacturing. The control of the robot is achieved by means of a pneumatic control box that can provide arbitrary pressures and can be built by only using purchased components, a laser cutter, and a soldering iron. For the walking performance of the robot, the pressure-angle calibration plays a crucial role. Therefore, a semi-automated method for the pressure-angle calibration is presented. At high inclines (&#62; 70&#176;), the robot can no longer reliably fix itself to the walking plane. Therefore, the gait pattern is modified to ensure that the feet can be fixed on the walking plane.

This protocol provides a detailed list of steps to be performed for the manufacturing, control and evaluation of the climbing performance of a gecko-inspired soft robot.

This protocol presents a method for manufacturing, control, and evaluation of the performance of a soft robot that can climb inclined flat surfaces with ...

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.

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.