Name: development of a nose-only inhalation toxicity test chamber that provides four exposure concentrations of nano-sized particles
Uploaded: 2019-03-18T12:30:00
Description: Watch this Scientific Journal Video about Development of a Nose-only Inhalation Toxicity Test Chamber That Provides Four Exposure Concentrations of Nano-sized Particles at JoVE.com

This research was supported by the Industrial Technology Innovation Program (10052901), Development of highly usable nanomaterial inhalation toxicity testing system in commerce, through the Korea Evaluation Institute of Industrial Technology by the Korean Ministry of Trade, Industry &#38; Energy.

1. Numerical analysis methods
<ol>
	<li>Perform the analysis of the flow field inside the chamber according to the geometrical shape, as described in Figure 1 and Table 114. 
	NOTE: A numerical analysis of the flow field according to the geometric shape predicts the flow of the aerosol and evaluates it as a testable device.</li>
	<li>Design the chamber with 4 stages x 12 columns, 48 ports in total, where the core is divided into an inner and ou...

<ol>
	<li>Phalen, R. F., Phalen, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+in+Inhalation+Toxicology.">Methods in Inhalation Toxicology.</a> Inhalation Exposure Methods. , 69-84 (1997).</li><li>Moss, O. R., James, R. A., Asgharian, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+exhaled+air+on+inhalation+exposure+delivered+through+a+directed-flow+nose-only+exposure+system.">Influence of exhaled air on inhalation exposure delivered through a directed-flow nose-only exposure system.</a> Inhalation Toxicology. 18, 45-51 (2006).</li><li>White, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fluid Mechanics. , (2004).</li><li>OECD TG 403. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OECD guideline of the testing of chemicals 403: Acute inhalation toxicity testing. , (2009).</li><li>OECD TG 436. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OECD guideline of the testing of chemicals 436: Acute inhalation toxicity - Acute Toxic Class Method. , (2009).</li><li>OECD GD 39. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Series on testing and assessment Number 39: Guidance document on acute Inhalation toxicity testing. , (2009).</li><li>OECD TG 412. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OECD guideline of the testing of chemicals 412: Subacute inhalation toxicity testing. , (2018).</li><li>OECD TG 413. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OECD guideline of the testing of chemicals 413: Subchronic inhalation toxicity testing. , (2018).</li><li>Cannon, W. C., Blanton, E. F., McDonald, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+flow-past+chamber:+an+improved+nose-only+exposure+system+for+rodents.">The flow-past chamber: an improved nose-only exposure system for rodents.</a> American Industrial Hygiene Association Journal. 44, 923-928 (1983).</li><li>Oldham, M. J., Phalen, R. F., Robinson, R. J., Kleinman, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+a+portable+whole-body+mouse+exposure+system.">Performance of a portable whole-body mouse exposure system.</a> Inhalation Toxicology. 16, 657-662 (2004).</li><li>Oldham, M. J., Phalen, R. F., Budiman, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+Predicted+and+Experimentally+Measured+Aerosol+Deposition+Efficiency+in+BALB/C+Mice+in+a+New+Nose-Only+Exposure+System.">Comparison of Predicted and Experimentally Measured Aerosol Deposition Efficiency in BALB/C Mice in a New Nose-Only Exposure System.</a> Aerosol Science and Technology. 43, 970-997 (2009).</li><li>Tuttle, R. S., Sosna, W. A., Daniels, D. E., Hamilton, S. B., Lednicky, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design,+assembly,+and+validation+of+a+nose-only+inhalation+exposure+system+for+studies+of+aerosolized+viable+influenza+H5N1virus+in+ferrets.">Design, assembly, and validation of a nose-only inhalation exposure system for studies of aerosolized viable influenza H5N1virus in ferrets.</a> Virology Journal. 7, 135 (2010).</li><li>Jeon, K., Yu, I. J., Ahn, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+newly+developed+nose-only+inhalation+exposure+chamber+for+nanoparticles.">Evaluation of newly developed nose-only inhalation exposure chamber for nanoparticles.</a> Inhalation Toxicology. 24 (9), 550-556 (2012).</li><li>Ji, J. H., 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=Twenty-Eight-Day+Inhalation+Toxicity+Study+of+Silver+Nanoparticles+in+Sprague-Dawley+Rats.">Twenty-Eight-Day Inhalation Toxicity Study of Silver Nanoparticles in Sprague-Dawley Rats.</a> Inhalation Toxicology. 19, 857-871 (2007).</li><li>Ostraat, M. L., Swain, K. A., Krajewski, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SiO2+Aerosol+Nanoparticle+Reactor+for+Occupational+Health+and+Safety+Studies.">SiO2 Aerosol Nanoparticle Reactor for Occupational Health and Safety Studies.</a> Journal of Occupational and Environmental Hygiene. 5, 390-398 (2008).</li><li>Pauluhn, J., Thiel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+approach+to+validation+of+directed-flow+nose-only+inhalation+chambers.">A simple approach to validation of directed-flow nose-only inhalation chambers.</a> Journal of Applied Toxicology. 27, 160-167 (2007).</li></ol>

Inhalation toxicity testing is currently the best method for evaluating aerosolized materials (particles and fibers), vapors, and gases inhaled by the human respiratory system14,15. There are two inhalation exposure methods: whole-body and nose-only. However, a nose-only system minimizes exposure by noninhalation routes, such as skin and eyes, and allows testing with minimal quantities of the test article, making it the preferred exposure method recommended by th...

Inhalation toxicity testing is the most reliable method for assessing the risks of chemical agents, particles, fibers, and nanomaterials1,2,3. Thus, most regulatory agencies require the submission of inhalation toxicity testing data when the exposure to chemicals, particles, fibers, and nanomaterials is via inhalation4,5,6,7,8. Currently, there are two types of inhalation toxicity systems: whole-body and nose-only exposure systems. A standard inhalation toxicity test system, either whole-body or nose-only, requires at least four chambers to expose animals such as rats and mice to four different concentrations, namely fresh air control and low, moderate, and high concentrations7,8. The Organization for Economic Co-operation and Development (OECD) test guidelines suggest that the selected target concentration should allow the identification of the target organ(s) and demonstration of a clear concentration response7,8. The high concentration level should result in a clear level of toxicity but not cause mortality or persistent signs that might lead to death or prevent a meaningful evaluation of the results7,8. The maximum achievable level or high concentration of the aerosols can be reached while meeting the particle size distribution standard. The moderate concentration level(s) should be spaced to produce a gradation of toxic effects between that of the low and high concentrations7,8. The low concentration level, which would preferably be a NOAEC (no-observed-adverse-effect concentration), should produce little or no sign of toxicity7,8. The whole-body chamber exposes animals in an unrestrained condition in wired cages, while the nose-only chamber exposes an animal in a restrained condition in the confined tube. The restraint prevents loss of aerosol by leakage around the animal. Due to the high volume of the whole-body chamber, it requires a large number of test articles to be exposed to experimental animals, while the restraint of the tube in the nose-only exposure system hinders animal movement and may cause discomfort or suffocation. Nevertheless, the regulatory OECD inhalation toxicity test guidelines prefer the use of nose-only inhalation systems4,5,6,7,8.
However, accommodating a four-chamber system, either whole-body or nose-only, is expensive, space-consuming, and requires a built-in air cleaning and circulation system. Furthermore, a four-chamber system can also require separate test article generators to expose animals to the desired concentrations, and a separate measurement apparatus to monitor the test article concentrations. Therefore, since standard inhalation toxicity testing involves significant investment, a more convenient and economical whole-body or nose-only exposure system needs to be developed for use in small research facilities. When designing an inhalation chamber, computational fluid dynamics (CFD) modeling is also frequently used to achieve particle, gas, or vapor uniformity9,10,11,12,13. Evaluation by numerical analyses and validation by experimental results has already been performed for the whole-body exposure chamber for mice10. For example, the air flow and particle trajectory have been modeled using CFD, and the uniformity of particle distribution has been measured in nine parts of the whole-body chamber10. Also, the nose-only chamber has been evaluated by numerical analysis by CFD13. After that, evaluation for the nose-only exposure chamber was performed by comparing the numerical analysis results with an experimental study using nanoparticles13.
This study presents a nose-only inhalation chamber system that can expose experimental animals to four different concentrations in one chamber. Initially designed using CFD and a numerical analysis, the proposed system is then compared with an experimental study using nanoscale sodium chloride particles to validate the uniformity and cross-contamination. The results presented here indicate that the presented nose-only chamber that can expose animals to four different concentrations can be used for animal exposure studies in small-scale academic and research facilities. The numerical analysis is set as follows, in the same manner as the experiment setting. For single-concentration exposure, the aerosol flow to the inner tower is set to 48 L/min and the sheath flow to the outer tower is set to 20 L/min. For multiconcentration exposure, the aerosol flow to the inner tower input is 11 L/min for each stage. The outlet differential pressure keeps at -100 Pa to maintain a smooth exhaust flow and prevent leakage. Assume the animal holders are closed and empty.

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			<td height="21" style="height:21px;width:216px;">FLUENT V.17.2&#160;</td>
			<td style="width:71px;">ANSYS</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Software</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">mass flow meter (MFM)</td>
			<td style="width:71px;">TSI</td>
			<td align="right" style="width:119px;">4043</td>
			<td></td>
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		<tr height="42">
			<td height="42" style="height:42px;width:216px;">SMPS (scanning mobility particle sizer)</td>
			<td style="width:71px;">Grimm&#160;</td>
			<td style="width:119px;">SMPS+C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">5-Jet atomizer&#160;</td>
			<td style="width:71px;">HCTM</td>
			<td style="width:119px;">5JA-1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mass flow controller (MFC)</td>
			<td style="width:71px;">Horiba</td>
			<td style="width:119px;">S48-32</td>
			<td></td>
		</tr>
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development of a nose-only inhalation toxicity test chamber that provides four exposure concentrations of nano-sized particles

Using a numerical analysis based on computerized fluid dynamics, a nose-only inhalation toxicity chamber with four different exposure concentrations is designed and validated for flow field uniformity and cross-contamination among the exposure ports for each concentration. The designed flow field values are compared with the measured values from exposure ports located horizontally and vertically. For this purpose, nanoscale sodium chloride particles are generated as test particles and introduced to the inhalation chamber to evaluate the cross-contamination and concentration maintenance among the chambers, for each concentration group. The results indicate that the designed multiconcentration inhalation chamber can be used in animal inhalation toxicity testing without cross-contamination among concentration groups. Moreover, the designed multiconcentration inhalation toxicity chamber can also be converted to a single-concentration inhalation chamber. Further testing with gas, organic vapor, or non-nanoscale particles will ensure the use of the chamber in the inhalation testing of other test articles.

Experimental set-up
Figure 1 shows a schematic diagram of a nose-only inhalation chamber system, including a particle generator with an MFC, nose-only chamber, and particle measurement instrument for monitoring the air quality, controller, and exhaust module, based on section 2 of the protocol.
Numerical analysis design
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Watch this Scientific Journal Video about Development of a Nose-only Inhalation Toxicity Test Chamber That Provides Four Exposure Concentrations of Nano-sized Particles at JoVE.com

Development of a Nose-only Inhalation Toxicity Test Chamber That Provides Four Exposure Concentrations of Nano-sized Particles

A nose-only inhalation toxicity chamber capable of testing inhalation toxicity at four different exposure concentrations was designed and validated for flow field uniformity and cross-contamination between the exposure ports for each concentration. Here, we present a protocol to confirm that the designed chamber is effective for inhalation toxicity testing.

Using a numerical analysis based on computerized fluid dynamics, a nose-only inhalation toxicity chamber with four different exposure concentrations is ...

We present a test protocol that complies with the OECD Guidelines for inhalation toxicity testing for single-and multiple-concentration exposure. The multiple-concentration inhalation chamber, which can test up to four exposure concentrations at once, will be more economical for small research institutes. To begin testing a single-concentration chamber, seal the chamber and check it for leaks at 500 and negative 500 pascals gauge for 30 minutes each.Then, set the clean air temperature to 23 degrees Celsius and 45%relative humidity. Start flowing clean air through the aerosol inlet and the sheath at 48 and 20 liters per minute, respectively. Set the exhaust pressure differential to negative 100 pascals.Once the flow has stabilized, measure the flow velocities at three randomly selected ports from each level to confirm that the flow is uniform. The flow rate should be about one liter per minute. Repeat the measurements twice more.Next, stop the air flow, and load a 0.1%by weight sodium chloride solution into the aerosol generation system. Start aerosol generation at 20 liters per minute with clean air as the carrier gas. Dilute the aerosol with 28 liters per minute of clean air.Set up a particle size measurement system, and randomly select three ports from each level of the chamber. Measure the particle size distribution at each selected port three times. To begin setting up a multi-concentration chamber, check it for leaks and set the clean air supply to 23 degrees Celsius and 45%relative humidity.Set the exhaust to maintain a differential pressure of negative 100 pascals. Then, connect a clean air supply to a port in the top compartment, and begin flowing clean air through the compartment at 11 liters per minute. Once the flow has stabilized, measure the flow velocity at each available port of the top compartment three times.Repeat this process for the other three compartments. Then, load a 0.1%by weight sodium chloride solution into the aerosol generator. Configure the aerosol dilution system to produce an aerosol flow at 11 liters per minute.Connect the aerosol inlet to the top compartment, wait for the flow to stabilize, and randomly select six ports from that compartment. Measure the particle size distribution at each of those ports three times using the particle size measurement system. Repeat this process for each compartment.Flush the compartments with clean air for 30 minutes when complete. Then, connect a clean air inlet to the top compartment, and flow clean air through it at 11 liters per minute. Configure the aerosol dilution system for low-concentration and high-concentration aerosol flows at 11 liters per minute.Connect the low-concentration line to the second highest compartment and the high-concentration line to the bottom compartment. Wait 10 minutes for the flows to stabilize. Then, randomly select one port from each of the three compartments, and measure the aerosol concentration at the selected ports 15 times each to check for cross-contamination.Both the single-concentration and multi-concentration exposure chambers showed good flow uniformity at each horizontal level of the chamber. The normalized flows were close to the values calculated during modeling of the system. Good flow uniformity was also observed vertically in the single-concentration chamber.The multi-concentration chamber has only one level of ports per compartment, so direct vertical uniformity measurements were not applicable. The particle concentration was also uniform horizontally for both chambers, and was uniform vertically for the single-concentration chamber. The aerosol concentrations in different compartments of the multi-concentration chamber showed relatively little variation across 15 measurements, indicating minimal cross-contamination between compartments.It is important to check for reproducibility throughout the procedure, especially during the experimental cross-contamination test performance evaluation test. Performance evaluation tests can be extended by comparing the experimental result to computational fluid dynamics modeling of the chamber system.

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Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.&#160; Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.&#160; The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.&#160; The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.&#160; We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.&#160;&#160; This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.

The technique of femtosecond four-wave mixing is described, including spectrally-resolved and time-resolved configurations. We illustrate the utility of this technique for the investigation of crucial physical properties in the III-V diluted magnetic semiconductors, afforded by its nonlinearity and high temporal resolution.

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products containing nanomaterials is also increasing. Evaluating the nanomaterial release from products containing nanomaterials is a crucial step in assessing the safety of these products, and has resulted in several international efforts to develop consistent and reliable technologies for standardizing the evaluation of nanomaterial release. In this study, the release of nanomaterials from products containing nanomaterials is evaluated using a chamber system that includes a condensation particle counter, optical particle counter, and sampling ports to collect filter samples for electron microscopy analysis. The proposed chamber system is tested using an abrasor and disc-type nanocomposite material specimens to determine whether the nanomaterial release is repeatable and consistent within an acceptable range. The test results indicate that the total number of particles in each test is within 20% from the average after several trials. The release trends are similar and they show very good repeatability. Therefore, the proposed chamber system can be effectively used for nanomaterial release testing of products containing nanomaterials.

Nanoparticle release is tested using a chamber system that includes a condensation particle counter, an optical particle counter and sampling ports to collect filter samples for microscopy analysis. The proposed chamber system can be effectively used for nanomaterial release testing with a repeatable and consistent data range.

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products ...

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

This protocol describes the operation of a liquid flow specimen holder for scanning transmission electron microscopy of AuNPs in water, as used for the observation of nanoscale dynamic processes.

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...