This document reviews acoustic trapping and manipulation of living cells. It discusses how acoustic manipulation works by trapping cells in pressure gradients using ultrasonic standing waves. The ability to non-invasively trap and manipulate live cells could enable applications like selective drug delivery and studying cell-cell interactions. Various acoustic manipulation techniques are described, including using opposing transducers to generate a standing wave for trapping cells. Characterizing the effects on cell viability and measuring acoustic forces are important. The project aims to design a sterilizable device that can optically image cells while acoustically trapping them. Initial tests trapping flour suggest the approach may work for cells.
fw1728_Final Year Project Report SubmissionFreddy White
The document is a final year project report submitted by Frederick A. O. White on April 27, 2015. It describes the design, development, and testing of an acoustic trapping device to trap live cells and microparticles. The device uses piezoelectric transducers to generate a standing wave acoustic field that successfully aligned human cells and 8 μm polymer beads while maintaining over 50% cell viability for up to two hours compared to controls. Computational analysis of particle distributions was used to study the quality and rate of alignment provided by the device.
1) The document discusses various optical properties of nano materials including absorption, scattering, refractive index, diffraction, and how they relate to electrical properties and interaction with electromagnetic radiation.
2) Key optical effects in nano materials are quantum confinement, which increases the band gap with decreasing size, and surface plasmons, which are coherent electron oscillations at interfaces that influence color.
3) The color of nano materials depends on size and can differ from the bulk material, as seen with different colored gold nanoparticles compared to bulk gold. Surface plasmons excited by light are responsible for the size-dependent colors.
The document summarizes a study on the effects of human tissue on the performance of a loop antenna. It discusses how the human body, being a lossy dielectric medium, interacts with the near field of antennas. This interaction causes changes to the antenna characteristics, reduces performance through power absorption in biological tissues, and changes the antenna impedance. The study specifically examines a rectangular loop antenna placed near a simplified three-layer model of the human torso. Results show the antenna's reflection coefficient and radiation pattern are affected by the distance between the antenna and body, as well as variations in the thickness of the lowest muscle layer to account for cardiac activity.
1) The document discusses using gold nanoparticles (AuNPs) to probe changes in cell activity and structure by measuring how the absorption spectra and agglomeration of AuNPs are affected by changes in the dielectric constant of the surrounding matrix.
2) Mie theory accurately predicts how changes in the dielectric constant of the matrix affect the absorption spectra of AuNPs. Absorption spectral shifts occur when AuNPs enter cells due to differences between the dielectric constant of cytoplasm and the surroundings.
3) The hypothesis is that measuring changes in the absorption spectra and agglomeration of AuNPs caused by varying the dielectric constant of different media can provide information about intracellular changes in cells.
1. The document discusses optical properties of minerals such as transparency, refractive index, colour, and luminescence. It explains how these properties are useful for identifying minerals.
2. Refractive index is a measure of how light propagates through a mineral and is calculated based on the angle of refraction. It varies between minerals based on their atomic structure.
3. A refractometer uses the phenomenon of total internal reflection at the critical angle to directly measure a mineral's refractive index, which is an important property for identification. The critical angle is the maximum angle at which light can pass from a dense medium into a rare medium.
This document is a thesis submitted by Erik Kirkland Gonzales to Oklahoma State University for the degree of Master of Science. The thesis investigates the phenomenon of cross polarization coupling (CPC) in optical microresonators. Through experiments on microspheres, the thesis demonstrates that CPC requires co-resonance between the transverse electric (TE) and transverse magnetic (TM) mode families. It is shown that applying strain to differentially tune the TE and TM modes allows controlling when CPC occurs. The thesis also explores scattering and Berry phase as potential mechanisms to explain the polarization coupling observed in microresonators.
This document provides an overview of key concepts in radiobiology for radiotherapy. It discusses the biological effects of ionizing radiation, including deterministic effects which have a dose threshold and include tissue injuries, and stochastic effects which have no threshold and include cancer induction. Fractionation of radiation doses is explained, along with the 5 R's that influence radiation response: repair, repopulation, reoxygenation, redistribution, and radiosensitivity. Direct and indirect radiation actions on DNA are also summarized.
fw1728_Final Year Project Report SubmissionFreddy White
The document is a final year project report submitted by Frederick A. O. White on April 27, 2015. It describes the design, development, and testing of an acoustic trapping device to trap live cells and microparticles. The device uses piezoelectric transducers to generate a standing wave acoustic field that successfully aligned human cells and 8 μm polymer beads while maintaining over 50% cell viability for up to two hours compared to controls. Computational analysis of particle distributions was used to study the quality and rate of alignment provided by the device.
1) The document discusses various optical properties of nano materials including absorption, scattering, refractive index, diffraction, and how they relate to electrical properties and interaction with electromagnetic radiation.
2) Key optical effects in nano materials are quantum confinement, which increases the band gap with decreasing size, and surface plasmons, which are coherent electron oscillations at interfaces that influence color.
3) The color of nano materials depends on size and can differ from the bulk material, as seen with different colored gold nanoparticles compared to bulk gold. Surface plasmons excited by light are responsible for the size-dependent colors.
The document summarizes a study on the effects of human tissue on the performance of a loop antenna. It discusses how the human body, being a lossy dielectric medium, interacts with the near field of antennas. This interaction causes changes to the antenna characteristics, reduces performance through power absorption in biological tissues, and changes the antenna impedance. The study specifically examines a rectangular loop antenna placed near a simplified three-layer model of the human torso. Results show the antenna's reflection coefficient and radiation pattern are affected by the distance between the antenna and body, as well as variations in the thickness of the lowest muscle layer to account for cardiac activity.
1) The document discusses using gold nanoparticles (AuNPs) to probe changes in cell activity and structure by measuring how the absorption spectra and agglomeration of AuNPs are affected by changes in the dielectric constant of the surrounding matrix.
2) Mie theory accurately predicts how changes in the dielectric constant of the matrix affect the absorption spectra of AuNPs. Absorption spectral shifts occur when AuNPs enter cells due to differences between the dielectric constant of cytoplasm and the surroundings.
3) The hypothesis is that measuring changes in the absorption spectra and agglomeration of AuNPs caused by varying the dielectric constant of different media can provide information about intracellular changes in cells.
1. The document discusses optical properties of minerals such as transparency, refractive index, colour, and luminescence. It explains how these properties are useful for identifying minerals.
2. Refractive index is a measure of how light propagates through a mineral and is calculated based on the angle of refraction. It varies between minerals based on their atomic structure.
3. A refractometer uses the phenomenon of total internal reflection at the critical angle to directly measure a mineral's refractive index, which is an important property for identification. The critical angle is the maximum angle at which light can pass from a dense medium into a rare medium.
This document is a thesis submitted by Erik Kirkland Gonzales to Oklahoma State University for the degree of Master of Science. The thesis investigates the phenomenon of cross polarization coupling (CPC) in optical microresonators. Through experiments on microspheres, the thesis demonstrates that CPC requires co-resonance between the transverse electric (TE) and transverse magnetic (TM) mode families. It is shown that applying strain to differentially tune the TE and TM modes allows controlling when CPC occurs. The thesis also explores scattering and Berry phase as potential mechanisms to explain the polarization coupling observed in microresonators.
This document provides an overview of key concepts in radiobiology for radiotherapy. It discusses the biological effects of ionizing radiation, including deterministic effects which have a dose threshold and include tissue injuries, and stochastic effects which have no threshold and include cancer induction. Fractionation of radiation doses is explained, along with the 5 R's that influence radiation response: repair, repopulation, reoxygenation, redistribution, and radiosensitivity. Direct and indirect radiation actions on DNA are also summarized.
The critical parameters for evaluating nanoparticle formulations include particle size, shape, zeta potential, polydispersity index, pH, aggregation, drug content, and solvent levels. Dynamic light scattering measures hydrodynamic diameter to assess size, while transmission electron microscopy and atomic force microscopy directly image particles for size, shape, and surface characteristics. Zeta potential indicates stability, and differential scanning calorimetry analyzes phase transitions by measuring enthalpy changes with temperature. Together, these techniques set quality standards and predict in vivo performance of nanoparticle drugs.
1. The document summarizes Tijmen G. Euser's research activities and publications. As a PhD student, he studied dynamic changes in light propagation in photonic crystals and demonstrated optical switching of photonic band gap crystals.
2. As a postdoc, his research included developing hollow-core photonic crystal fibers for optofluidic microreactors, waveguide-based micromanipulation techniques, and spatial light modulation applications. This work enabled new experiments in fields like photochemistry, microparticle transport, and fiber-based spectroscopy.
3. His publications include over 40 peer-reviewed papers investigating topics like optofluidic reactors, optical trapping and propulsion in fibers, spatial mode control
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
This document reviews the use of quantum dots for bioimaging applications. It discusses:
1) The synthesis of quantum dots, particularly CdSe/ZnS core/shell structures, and methods to tune their optical properties.
2) Modification of quantum dot surfaces with ligands to make them water soluble and biocompatible while maintaining fluorescence. Common surface modifications include adding carboxylic acids, silica shells, and encapsulation in micelles.
3) Applications of quantum dots in biology, including labeling of proteins and targeting of specific cell surface receptors due to their photostability and ability to detect multiple signals simultaneously.
Metamaterials are macroscopic composites that exhibit properties not found in nature due to their designed cellular architecture and chemical composition. They allow realization of all possible material properties by designing different cellular structures. The term was coined in 1999. While natural materials occur at discrete points, metamaterials allow realization of most material properties. Their history includes using split-ring resonators to realize negative permeability and perfect lenses. Applications include antennas, cloaking, terahertz modulators, absorbers, and elastic metamaterials. Many predicted linear and nonlinear phenomena remain to be experimentally demonstrated.
This document summarizes research on high frequency dielectric materials for applications in medicine and telecommunications. It discusses how materials with high permittivity values (>1000) can increase MRI sensitivity in the MHz range, while low permittivity (<10) materials with low loss are important for 5G and above applications to reduce attenuation. Characterization techniques for accurately measuring dielectric properties from MHz to THz frequencies are also reviewed. Specific materials discussed include barium strontium titanate for MRI and quartz, fused silica, and glass for wireless applications.
This document discusses various characterization techniques for bionanomaterials. Structural characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are used to determine structure and morphology. Chemical characterization techniques like optical spectroscopy, electron spectroscopy, and mass spectrometry are used to determine surface and interior atoms, compounds, and spatial distributions. Additional techniques discussed include small angle X-ray scattering (SAXS) and gas adsorption. Characterization at the nanoscale requires high resolution and sensitivity to provide atomic-level detail.
Magnetic nanoparticles applications and bioavailability for cancer therapyPravin Chinchole
Magnetic nanoparticles can be used for cancer therapy applications. They can be coated or encapsulated to be bioavailable. When exposed to an external alternating magnetic field, the nanoparticles generate heat through hysteresis, friction, and relaxation effects. This localized hyperthermia can directly kill cancer cells or induce heat shock proteins to stimulate anti-cancer immunity. The nanoparticles can also be used for magnetic drug delivery, where drugs are attached and targeted to tumor sites using an external magnetic field, requiring lower doses than conventional treatment and reducing side effects. Studies have shown magnetic nanoparticle hyperthermia and drug delivery can significantly reduce tumor growth in animal models.
Novel experimental observations in percolative systemsRAVI BHATIA
The presentation in based on interesting experimental results of percolative systems. A weak temperature dependence of conductivity is observed in composite of 0.4 wt %. The coercivity of Fe-MWNT/PS composites varies non-monotonically as a function of MWNT loading.
The document discusses using magnetic nanoparticles for hyperthermia cancer therapy. It notes that resistance is a major challenge in cancer treatment. Mild hyperthermia between 42-45°C can induce apoptosis in cancer cells without damaging normal tissues. The document then describes a new type of nanoparticle called RA IN (resistance-free apoptosis-inducing nanoparticle) that aims to overcome resistance. The RA IN contains two subunits - one to inhibit heat shock proteins that protect cancer cells from heat-induced apoptosis, and another magnetic nanoparticle subunit to generate localized heat with an external magnetic field to kill cancer cells through apoptosis.
This document discusses central axis depth doses in water for both SSD and SAD techniques. For SSD technique:
- Percentage depth dose (PDD) curves measure attenuation at different depths and are affected by beam quality, field size, and SSD.
- Buildup region occurs as secondary electrons deposit energy downstream, increasing dose with depth until maximum.
- Depth dose maximum (zmax) depends on beam energy and field size.
- PDD increases with larger field sizes due to increased scatter radiation.
- PDD increases with longer SSD due to the inverse square law of radiation intensity.
This document discusses single molecule detection using localized surface plasmon resonance of gold nanoparticles. It notes that single molecule detection is needed for early disease detection but current labeling techniques are destructive, not real-time, and don't allow virus information extraction. Label-free detection monitors inherent optical and dielectric properties but has sensitivity and specificity issues. Localized surface plasmon resonance exploits the resonant oscillation of conduction electrons in gold nanoparticles stimulated by light, producing a shift in resonant frequency when the refractive index changes due to molecule binding. This enables label-free single molecule protein detection using a single plasmonic nanoparticle sensor.
Study of magnetic and structural and optical properties of Zn doped Fe3O4 nan...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes synthesizing of magnetic nanocomposite with co-precipitation
method.
Materials and Methods:
Magnetic ZnxFe3-xO4 nanoparticles with 0-14% zinc doping (x=0, 0.025, 0.05, 0.075, 0.1 and 0.125) were successfully synthesized by co-precipitation method. The prepared zinc-doped Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and UV-Vis spectroscopy.
Results:
results obtained from X-ray diffraction pattern have revealed the formation of single phase nanoparticles with cubic inverse spinal structures which size varies from 11.13 to 12.81 nm. The prepared nanoparticles have also possessed superparamagnetic properties at room temperature and high level of saturation magnetization with the maximum level of 74.60 emu/g for x=0.075. Ms changing in pure magnetite nanoparticles after impurities addition were explained based on two factors of “particles size” and “exchange interactions”. Optical studies results revealed that band gaps in all Zn-doped NPs are higher than pure Fe3O4. As doping percent increases, band gap value decreases from 1.26 eV to 0.43 eV.
Conclusion:
These magnetic nanocomposite structures since having superparamagnetic property
offer a high potential for biosensing and biomedical application.
This document describes how researchers used optical tweezers to stretch and measure the elasticity of DNA strands. Optical tweezers use refracted and reflected laser light to apply tiny forces (piconewtons) to manipulate microscopic objects like DNA. The researchers attached one end of a DNA strand to a bead trapped by the tweezers and the other end to a movable stage. By varying the stage position and measuring the counteracting force from the tweezers, they could determine how much force was required to stretch the DNA and analyze its mechanical properties.
Insertion layer in a mid ir band-pass filter structure to improve optical tra...Alexander Decker
This document describes research on improving the optical transmittance of a mid-infrared band-pass filter structure. The researchers modeled a filter structure of alternating germanium and zinc sulfide layers with a quartz substrate. They found that inserting an additional germanium layer improved transmittance. Specifically, a structure with 10 layer pairs and an 80% thickness germanium insertion layer had the highest transmittance of around 0.9 compared to structures without an insertion layer or with thicker insertion layers. The insertion layer location on the bottom near the substrate also produced better results than on top. Varying the layer thicknesses shifted the transmission spectrum but did not significantly affect other characteristics.
STUDY ON FIBER GRATINGS AND ITS CHARACTERIZATIONDr. Ved Nath Jha
Good potential uses in fiber and fiber lasers have been seen through Random Fiber Gratings (RFGs). However, a quantitative link has never been studied between the RFG's randomness and spectral reaction. This paper first experimentally characterizes two RFGs of varying degrees of randomness by optical frequency reflectometry (OFDR). The high degree of randomness indicates that the grating intensity is limited and the strength variations in spatial domain are large. The experimental findings show. Study establishes the theoretical basis for the optimization configuration and implementation of the long-term fiber grating in the area of fiber optics sensing and communication.
DEVELOPMENT OF OPTICAL PARAMETER CALCULATIONS OF THE PROBES IN WATERDr. Ved Nath Jha
This document describes the development of optical parameter calculations for probes used in water sensing. Three probes (a, b, c) of varying nanoparticle size were developed and their plasma and collision wavelengths were calculated based on experimental measurements in water and air. The probes showed decreasing collision wavelength but nearly constant plasma wavelength with increasing nanoparticle size. Models were developed to calculate output intensity based on the dielectric constant of the surrounding medium. Distinct dips in output intensity correlated with different dielectric components when mixtures were tested, showing ability to detect multiple impurities simultaneously. The probes function best for dielectric constants between 1.4-2.0 and silver nanoparticles provide sensitivity towards targeted impurities in water quality monitoring.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
The document discusses the use of quantum dots (QDs) for biomedical applications such as bioimaging and therapy. It provides an overview of the photophysical properties of QDs that make them advantageous over organic dyes for imaging. Various biomedical applications of QDs are described, including in vitro and in vivo imaging, biosensing, photodynamic therapy, drug delivery, and gene delivery. Finally, the document outlines a research proposal to develop MoS2@polyaniline nanohybrids for dual-model imaging and synergistic photothermal/radiation therapy of tumors.
Bas et al. - 2015 - Coherent control of injection currents in high-quaDerek Bas
1) The document describes an experiment using two-color quantum interference to inject photocurrents in films of the topological insulator Bi2Se3.
2) High-quality Bi2Se3 films were grown by molecular beam epitaxy and characterized using reflection high-energy electron diffraction, X-ray reflectivity, and diffraction.
3) Photocurrents were injected in the Bi2Se3 films using two ultrashort optical pulses at different frequencies, and the emitted terahertz radiation was measured. The injection current followed the expected dependences on the relative phase and irradiances of the optical pulses, confirming the third-order nonlinear optical mechanism.
Reach Software offers many benefits that are innate for any accounting software; for instance, it allows us to perform accounting tasks more quickly, efficiently, and accurately. It allows us to keep track of our financial progress and performance.
The critical parameters for evaluating nanoparticle formulations include particle size, shape, zeta potential, polydispersity index, pH, aggregation, drug content, and solvent levels. Dynamic light scattering measures hydrodynamic diameter to assess size, while transmission electron microscopy and atomic force microscopy directly image particles for size, shape, and surface characteristics. Zeta potential indicates stability, and differential scanning calorimetry analyzes phase transitions by measuring enthalpy changes with temperature. Together, these techniques set quality standards and predict in vivo performance of nanoparticle drugs.
1. The document summarizes Tijmen G. Euser's research activities and publications. As a PhD student, he studied dynamic changes in light propagation in photonic crystals and demonstrated optical switching of photonic band gap crystals.
2. As a postdoc, his research included developing hollow-core photonic crystal fibers for optofluidic microreactors, waveguide-based micromanipulation techniques, and spatial light modulation applications. This work enabled new experiments in fields like photochemistry, microparticle transport, and fiber-based spectroscopy.
3. His publications include over 40 peer-reviewed papers investigating topics like optofluidic reactors, optical trapping and propulsion in fibers, spatial mode control
Nanoparticles are solid colloidal particles ranging in size from 10 to 1000 nm.
Nanoparticles are made of a macromolecular material which can be of synthetic or natural origin.
This document reviews the use of quantum dots for bioimaging applications. It discusses:
1) The synthesis of quantum dots, particularly CdSe/ZnS core/shell structures, and methods to tune their optical properties.
2) Modification of quantum dot surfaces with ligands to make them water soluble and biocompatible while maintaining fluorescence. Common surface modifications include adding carboxylic acids, silica shells, and encapsulation in micelles.
3) Applications of quantum dots in biology, including labeling of proteins and targeting of specific cell surface receptors due to their photostability and ability to detect multiple signals simultaneously.
Metamaterials are macroscopic composites that exhibit properties not found in nature due to their designed cellular architecture and chemical composition. They allow realization of all possible material properties by designing different cellular structures. The term was coined in 1999. While natural materials occur at discrete points, metamaterials allow realization of most material properties. Their history includes using split-ring resonators to realize negative permeability and perfect lenses. Applications include antennas, cloaking, terahertz modulators, absorbers, and elastic metamaterials. Many predicted linear and nonlinear phenomena remain to be experimentally demonstrated.
This document summarizes research on high frequency dielectric materials for applications in medicine and telecommunications. It discusses how materials with high permittivity values (>1000) can increase MRI sensitivity in the MHz range, while low permittivity (<10) materials with low loss are important for 5G and above applications to reduce attenuation. Characterization techniques for accurately measuring dielectric properties from MHz to THz frequencies are also reviewed. Specific materials discussed include barium strontium titanate for MRI and quartz, fused silica, and glass for wireless applications.
This document discusses various characterization techniques for bionanomaterials. Structural characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are used to determine structure and morphology. Chemical characterization techniques like optical spectroscopy, electron spectroscopy, and mass spectrometry are used to determine surface and interior atoms, compounds, and spatial distributions. Additional techniques discussed include small angle X-ray scattering (SAXS) and gas adsorption. Characterization at the nanoscale requires high resolution and sensitivity to provide atomic-level detail.
Magnetic nanoparticles applications and bioavailability for cancer therapyPravin Chinchole
Magnetic nanoparticles can be used for cancer therapy applications. They can be coated or encapsulated to be bioavailable. When exposed to an external alternating magnetic field, the nanoparticles generate heat through hysteresis, friction, and relaxation effects. This localized hyperthermia can directly kill cancer cells or induce heat shock proteins to stimulate anti-cancer immunity. The nanoparticles can also be used for magnetic drug delivery, where drugs are attached and targeted to tumor sites using an external magnetic field, requiring lower doses than conventional treatment and reducing side effects. Studies have shown magnetic nanoparticle hyperthermia and drug delivery can significantly reduce tumor growth in animal models.
Novel experimental observations in percolative systemsRAVI BHATIA
The presentation in based on interesting experimental results of percolative systems. A weak temperature dependence of conductivity is observed in composite of 0.4 wt %. The coercivity of Fe-MWNT/PS composites varies non-monotonically as a function of MWNT loading.
The document discusses using magnetic nanoparticles for hyperthermia cancer therapy. It notes that resistance is a major challenge in cancer treatment. Mild hyperthermia between 42-45°C can induce apoptosis in cancer cells without damaging normal tissues. The document then describes a new type of nanoparticle called RA IN (resistance-free apoptosis-inducing nanoparticle) that aims to overcome resistance. The RA IN contains two subunits - one to inhibit heat shock proteins that protect cancer cells from heat-induced apoptosis, and another magnetic nanoparticle subunit to generate localized heat with an external magnetic field to kill cancer cells through apoptosis.
This document discusses central axis depth doses in water for both SSD and SAD techniques. For SSD technique:
- Percentage depth dose (PDD) curves measure attenuation at different depths and are affected by beam quality, field size, and SSD.
- Buildup region occurs as secondary electrons deposit energy downstream, increasing dose with depth until maximum.
- Depth dose maximum (zmax) depends on beam energy and field size.
- PDD increases with larger field sizes due to increased scatter radiation.
- PDD increases with longer SSD due to the inverse square law of radiation intensity.
This document discusses single molecule detection using localized surface plasmon resonance of gold nanoparticles. It notes that single molecule detection is needed for early disease detection but current labeling techniques are destructive, not real-time, and don't allow virus information extraction. Label-free detection monitors inherent optical and dielectric properties but has sensitivity and specificity issues. Localized surface plasmon resonance exploits the resonant oscillation of conduction electrons in gold nanoparticles stimulated by light, producing a shift in resonant frequency when the refractive index changes due to molecule binding. This enables label-free single molecule protein detection using a single plasmonic nanoparticle sensor.
Study of magnetic and structural and optical properties of Zn doped Fe3O4 nan...Nanomedicine Journal (NMJ)
Objective(s):
This paper describes synthesizing of magnetic nanocomposite with co-precipitation
method.
Materials and Methods:
Magnetic ZnxFe3-xO4 nanoparticles with 0-14% zinc doping (x=0, 0.025, 0.05, 0.075, 0.1 and 0.125) were successfully synthesized by co-precipitation method. The prepared zinc-doped Fe3O4 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and UV-Vis spectroscopy.
Results:
results obtained from X-ray diffraction pattern have revealed the formation of single phase nanoparticles with cubic inverse spinal structures which size varies from 11.13 to 12.81 nm. The prepared nanoparticles have also possessed superparamagnetic properties at room temperature and high level of saturation magnetization with the maximum level of 74.60 emu/g for x=0.075. Ms changing in pure magnetite nanoparticles after impurities addition were explained based on two factors of “particles size” and “exchange interactions”. Optical studies results revealed that band gaps in all Zn-doped NPs are higher than pure Fe3O4. As doping percent increases, band gap value decreases from 1.26 eV to 0.43 eV.
Conclusion:
These magnetic nanocomposite structures since having superparamagnetic property
offer a high potential for biosensing and biomedical application.
This document describes how researchers used optical tweezers to stretch and measure the elasticity of DNA strands. Optical tweezers use refracted and reflected laser light to apply tiny forces (piconewtons) to manipulate microscopic objects like DNA. The researchers attached one end of a DNA strand to a bead trapped by the tweezers and the other end to a movable stage. By varying the stage position and measuring the counteracting force from the tweezers, they could determine how much force was required to stretch the DNA and analyze its mechanical properties.
Insertion layer in a mid ir band-pass filter structure to improve optical tra...Alexander Decker
This document describes research on improving the optical transmittance of a mid-infrared band-pass filter structure. The researchers modeled a filter structure of alternating germanium and zinc sulfide layers with a quartz substrate. They found that inserting an additional germanium layer improved transmittance. Specifically, a structure with 10 layer pairs and an 80% thickness germanium insertion layer had the highest transmittance of around 0.9 compared to structures without an insertion layer or with thicker insertion layers. The insertion layer location on the bottom near the substrate also produced better results than on top. Varying the layer thicknesses shifted the transmission spectrum but did not significantly affect other characteristics.
STUDY ON FIBER GRATINGS AND ITS CHARACTERIZATIONDr. Ved Nath Jha
Good potential uses in fiber and fiber lasers have been seen through Random Fiber Gratings (RFGs). However, a quantitative link has never been studied between the RFG's randomness and spectral reaction. This paper first experimentally characterizes two RFGs of varying degrees of randomness by optical frequency reflectometry (OFDR). The high degree of randomness indicates that the grating intensity is limited and the strength variations in spatial domain are large. The experimental findings show. Study establishes the theoretical basis for the optimization configuration and implementation of the long-term fiber grating in the area of fiber optics sensing and communication.
DEVELOPMENT OF OPTICAL PARAMETER CALCULATIONS OF THE PROBES IN WATERDr. Ved Nath Jha
This document describes the development of optical parameter calculations for probes used in water sensing. Three probes (a, b, c) of varying nanoparticle size were developed and their plasma and collision wavelengths were calculated based on experimental measurements in water and air. The probes showed decreasing collision wavelength but nearly constant plasma wavelength with increasing nanoparticle size. Models were developed to calculate output intensity based on the dielectric constant of the surrounding medium. Distinct dips in output intensity correlated with different dielectric components when mixtures were tested, showing ability to detect multiple impurities simultaneously. The probes function best for dielectric constants between 1.4-2.0 and silver nanoparticles provide sensitivity towards targeted impurities in water quality monitoring.
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
The document discusses the use of quantum dots (QDs) for biomedical applications such as bioimaging and therapy. It provides an overview of the photophysical properties of QDs that make them advantageous over organic dyes for imaging. Various biomedical applications of QDs are described, including in vitro and in vivo imaging, biosensing, photodynamic therapy, drug delivery, and gene delivery. Finally, the document outlines a research proposal to develop MoS2@polyaniline nanohybrids for dual-model imaging and synergistic photothermal/radiation therapy of tumors.
Bas et al. - 2015 - Coherent control of injection currents in high-quaDerek Bas
1) The document describes an experiment using two-color quantum interference to inject photocurrents in films of the topological insulator Bi2Se3.
2) High-quality Bi2Se3 films were grown by molecular beam epitaxy and characterized using reflection high-energy electron diffraction, X-ray reflectivity, and diffraction.
3) Photocurrents were injected in the Bi2Se3 films using two ultrashort optical pulses at different frequencies, and the emitted terahertz radiation was measured. The injection current followed the expected dependences on the relative phase and irradiances of the optical pulses, confirming the third-order nonlinear optical mechanism.
Reach Software offers many benefits that are innate for any accounting software; for instance, it allows us to perform accounting tasks more quickly, efficiently, and accurately. It allows us to keep track of our financial progress and performance.
On Monday 9th November 16:00 The Food Foundation and Public Health England convened a parliamentary sugar roundtable to discuss the evidence behind the new dietary advice on sugar consumption.
This presentation, delivered by Dr Alison Tedstone, Director of Health and Obesity at Public Health England, talks through the SACN report and evidence package following the release of Sugar Reduction: The Evidence for Action (Found below)
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/470179/Sugar_reduction_The_evidence_for_action.pdf
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Dự án: “Nâng cao năng lực cung cấp thông tin cho các hiệp hội doanh nghiệp và cơ quan truyền thông trong quá trình thực thi FLEGT” được tài trợ bởi EU FAO FLEGT
This document discusses methods for measuring food insecurity in developed countries like the UK. It begins by reviewing early discussions around defining and quantifying food insecurity/hunger in North America. It then examines qualitative research exploring experiences of food insecurity. Common themes included uncertainty over food supply, shortage of food, unsuitable/monotonous diets, and reduced food quality and quantity.
The document outlines the development of standardized household food security surveys like the USDA Household Food Security Survey Module. It compares this tool to other measures like the FAO Food Insecurity Experience Scale. It acknowledges limitations of these tools in fully capturing all dimensions of food security like availability, utilization, and stability over time. Finally, it considers reasons
Un hombre encuentra una lámpara mágica y libera a un genio. El genio solo le concederá un deseo porque está cansado de sacarlo de la lámpara. El hombre pide un puente hasta Nueva York pero el genio dice que es imposible. Finalmente, el hombre desea poder entender a las mujeres para hacerlas felices. El genio le ofrece construir el puente en su lugar.
El documento expresa el deseo de que arda un mundo injusto donde se fabrican y venden armas, unos niños van a la guerra mientras otros van a la escuela, y la gente trabaja en precarias condiciones. Pide que arda con un fuego purificador que traiga hermandad, espiritualidad, sinceridad, justicia y bondad, y que este fuego arda sin cesar de generación en generación.
El documento presenta varios párrafos que reflexionan sobre el proceso de superación personal tras pasar por momentos difíciles o de pérdida. Alienta al lector a dejar atrás el pasado doloroso, creer en sí mismo, soñar en grande y comenzar de nuevo con un nuevo proyecto de vida y objetivos.
Una mujer de 20 años llamada Denisse Guerrero disfruta pasar tiempo con su familia y amigos, explorando nuevos lugares. Ha estudiado en tres colegios, incluyendo el Colegio Philippe Cousteau, el Colegio Emprender y el Colegio Obispo Alvear.
Jesús comparte la última cena con sus discípulos, donde les entrega pan y vino como símbolos de su cuerpo y su sangre. Les pide que lo hagan en memoria suya para recordar su sacrificio y seguir su ejemplo de amor y entrega hacia los demás.
Ultrasound Targeted Microbubble Destruction Research ProjectChristina Amaral
This is a presentation of my final research project for my Introduction to Biomedical Engineering course.* Together with a partner, I conducted a thorough internet research of the newly emerging field of drug delivery using microbubbles activated by ultrasound technology. We presented to Biomedical Engineering faculty, graduates, and students at a formal poster session the advantages of microbubble technology as an alternative method to traditional chemotherapy, as well as its potential in thrombolysis and gene therapy.
*Note: The bibliography for this project is not attached; it is a separate document also uploaded onto this website.
This document summarizes several abstracts presented at the AIP Bi-Annual Postgraduate Conference on September 7-8, 2001. The abstracts covered topics related to gravitational waves, opto-acoustic interactions, quantum mechanics, spin waves, frequency sources, phonon lasers, nanostructure fabrication, and silicon nanowire growth. Experimental and theoretical work was presented across various fields of physics including general relativity, quantum physics, condensed matter physics, and nanotechnology.
The document discusses capacitive micromachined ultrasonic transducers (CMUTs) and the calculation of mutual impedance between neighboring cells in CMUT arrays. It provides background on CMUTs, including their fabrication, operating principle, advantages over piezoelectric transducers, and applications. The document focuses on how the acoustic loading from neighboring cells affects each cell in a CMUT array. It states that the mutual acoustic impedance must be considered to accurately model a multi-cell CMUT element. It then describes calculating the mutual impedance between two neighboring cells in a CMUT array using MATLAB simulation.
Controlling sound transmission with density-near-zero acoustic membrane networkellunatico69
This document describes a design for a density-near-zero (DNZ) acoustic membrane network that can control sound transmission. The network is made of circular membranes arranged in a square lattice inside a waveguide. The unit cell is modeled as an equivalent lumped-circuit of inductors and capacitors. Simulations show the effective mass density approaches zero near 987 Hz, the resonance frequency predicted by the circuit model, demonstrating DNZ behavior. Further simulations then examine how the DNZ membrane network can achieve applications like cloaking, high transmission through sharp corners, and wave splitting.
This document discusses different types of photonic sensors including surface plasmon resonance sensors, whispering gallery mode sensors, and photonic crystal sensors.
Surface plasmon resonance sensors detect changes at a metal-dielectric interface and are used for ultrasensitive immunoassays. Whispering gallery mode sensors can detect nanoparticles smaller than 100 nm by measuring changes in resonant frequencies as particles deposit inside an optical cavity. Photonic crystal sensors use a photonic band gap to selectively reflect certain wavelengths of light. Changes in materials deposited on the photonic crystal surface cause shifts in the reflected wavelengths that can be measured.
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This document discusses the safety of cellphone radiation based on photon energy levels. It makes three key points:
1) Cellphones operate in the classical wave limit of high photon densities, not the single photon limit, so the energy of individual photons is irrelevant to safety.
2) The photon flux from cellphones is many orders of magnitude greater than levels that have produced biological effects in studies. Effects could result from coherent photon energies combining to do work inside cells.
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Modeling ultrasonic attenuation coefficient and comparative study with the pr...IOSR Journals
Many phenomena can be responsible for the attenuation of sound through the suspensions depending on the nature of the particles of the fluid and the frequency range of interest. In particular we can make a distinction between the diffusion mechanisms corresponding to a geometric redirection of the incident wave and the dissipative phenomena, like the thermal and viscous losses. In this work, we are interested in propagation of the ultrasonic waves into suspensions of clay rigid particles with a size between 1 and 50 microns, for which the thermal phenomena and visco-inertial dominate. In this case the dipole diffusion of the wave induced differential motion between the dispersed phase (clay grain) and the continuous phase (distilled water) is coupled to the viscous dissipation in the matching motion of this brake. In this paper, we present the main theories known in calculating the ultrasonic attenuation and velocity coefficient. Such theories permit to take accounts all the orders of interaction, unlike the theoretical of multiple diffusion that remains limited to lower concentrations. Finally, the results calculated by the principal theories will be compared against earlier experimental results obtained from this work.
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the purpose of this
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This document numerically analyzes the wave function of atoms under the combined effects of an optical lattice trapping potential and a harmonic oscillator potential, as used in Bose-Einstein condensation experiments. It employs the Crank-Nicolson scheme to solve the Gross-Pitaevskii equation. The results show that the wave function distribution responds to parameters like the trapping frequencies ratio, optical lattice intensity, chemical potential, and energy. Careful adjustment of the time step and grid spacing is needed to satisfy conservation of norms and energy as required by the physical system. Distributions of the overlapping potentials for different q-factors are presented.
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1. A Brief Review of Acoustic Trapping and Manipulation of Living cells
Frederick A. O. White
(Dated: December 3, 2014)
The development of centimetre and micrometre scale acoustic manipulation systems has led to increasing
interest in their possible applications in biophysics. This review investigates the current state of the art in
acoustic manipulation, its challenges and potential applications to the study of live cells. The ability to trap
and manipulate live cells raises the possibility of selective labelling and drug delivery to subsets of cells in a
controlled environment. Various approaches to manipulating cells are considered and discussed.
INTRODUCTION
Acoustic trapping was first observed in 1868 during
Kundt’s tube experiments, where cork dust aligned with the
standing wave in an air-filled resonant cylinder[1]. The first
theoretical description of the acoustic radiation force for in-
compressible spheres was produced in 1934 by King[2]. This
was extended to compressible particles in 1955 by Yosioka
and Kawasima[3] and finally generalised for viscid fluids in
1962 by Gor’kov, whose derivation is most commonly used
today[4].
Acoustic manipulation traps cells by the pressure gradient
produced in a non-uniform acoustic field. Interest in acoustic
manipulation for biophysics applications has grown rapidly
over the last decade. Acoustic manipulation enables non-
invasive, non-contact trapping of cells and particles without
the need to remove them from their culture[5]. This can ben-
efit the study of cells by allowing the study of groups of cells
in a controlled environment over longer periods than possible
if cells can move freely. Acoustic manipulation is less likely
to damage cells than mechanical techniques and allows trap-
ping without affecting the environment around the cell, mak-
ing it suitable for delicate cell cultures and precise studies[6].
Acoustic manipulation has advantages over other non-contact
methods being cheap, easy to integrate into microfluid sys-
tems and maintaining cell viability[6]. The only requirement
of cells for acoustic trapping is a density and compressibility
contrast with the cell-carrying medium, so it is applicable to
a wide range of cells and particles[7, 8]. One disadvantage
is the relatively low precision and poor single-cell control, al-
though recent work has begun to mitigate these issues using
higher order Bessel functions while manipulating µm scale
polystyrene beads[9]. The main focus of this review, how-
ever, will be the application of acoustic manipulation to living
cells, and its success and future potential for cell studies.
THEORY
Acoustic manipulation uses the primary radiation force
(PRF). This arises when an ultrasonic standing wave inter-
acts by scattering off a particle or cell with an acoustic con-
trast to the fluid medium. The PRF moves particles to a point
of either maximum or minimum acoustic potential depending
on this contrast[5]. The standard approach, originally due to
Gor’kov[4], is to write the PRF as the gradient of the acous-
tic potential. A full derivation is available in Bruus’ 2007
paper[10] the result of which is:
Frad
= − Urad
(1a)
Urad
=
4π
3
a3
f1
1
2
κ0 p2
1 − f2
3
4
ρ0 v2
1 (1b)
where v2
1 and p2
1 are the time-averaged incoming velocity
and pressure fields squared, κ0 and ρ0 are the compressibility
and density of the fluid and the subscript p in Eq.2 denotes
the same quantities for the spherical particle radius a. The
quantities f1 and f2 are dimensionless scattering coefficients
defined by the value of the compressibility and density of the
particle compared to that of the surrounding fluid.
f1(˜κ) = 1 − ¯κ with ¯κ =
κp
κ0
(2a)
f2(˜ρ) =
2(˜ρ − 1)
2˜ρ + 1
with ˜ρ =
ρp
ρ0
(2b)
The form of these coefficients means that most cells will
move to the minima in the potential since their density tends
to be higher and their compressibility lower than the surround-
ing medium[5]. Once the first cells are entrapped, secondary
forces gather nearby cells into a cluster centred on the nodal
point. It is significant that the acoustic force experienced
by a cell scales with volume, not radius, so smaller particles
are harder to manipulate as the Stokes’ drag they experience
scales with radius and so falls off more slowly than the applied
trapping force.
ALTERNATIVES TO ACOUSTIC MANIPULATION
There are several alternative approaches to non-contact cell
handling besides acoustic manipulation. Optical tweezers trap
cells at the focal point of a laser beam. This has the ad-
vantage of extreme precision, on the scale of nanometres.
However, the laser can deposit significant energy in cells
and the equipment is difficult to integrate with cell-culture
containers[6, 11]. Additionally, optical tweezers are limited
to <10µm cell diameters, whereas acoustic manipulation can
2. 2
reach the range of ∼100µm[11]. The ability of optical tweez-
ers to manipulate single cells has led to interest in combining
optical tweezers and acoustic manipulation to use the best fea-
tures of both: acoustic manipulation to handle large groups of
cells and operate over relatively large areas but with the pre-
cision of optical tweezers for single cells[12].
Magnetic trapping and electrophoresis use non-uniform
magnetic and electric fields respectively. Magnetic trapping is
limited in its applicability to live-cell studies by the need for
either naturally magnetic cells or doped cells. Electrophore-
sis provides better precision than acoustic manipulation but
requires strong gradients in the field, which limits the work-
ing distance as the electrodes must be closely spaced. There is
also the risk of Joule heating in fluid media which can damage
cells[13].
APPLICATIONS OF ACOUSTIC MANIPULATION
The ability to immobilise cells is useful as it allows the
study of particular groups of cells in a strictly controlled en-
vironment, since a well designed acoustic device should not
significantly affect the medium or cells. This makes it suit-
able for for a wide range of biophysics applications.
Acoustic manipulation has been applied in high-
resolution cell response studies and to characterise cell–cell
interactions[14]. Other applications include reducing the
time needed to create 3D cell clusters and enhance bioassays,
which may have applications in tissue engineering[11].
Ultrasound in the MHz range has been applied for filtration
and cell gathering since the 90s[15, 16]. Initially filtration
was achieved by agglomerating cells using acoustic ma-
nipulation and allowing them to settle before drawing off
clear fluid. More recently work on micrometre scales has
achieved in-flow filtering and cell washing. Working with
flowing media allows cell environments to be maintained
during processing[5, 17]. A recent application of acoustic
manipulation is in the study of non-adherent cells, where the
ability to group cells that do not naturally cluster or grow on
surface cultures is of great benefit[14].
DESIGN OF DEVICES
The standing wave field required for acoustic manipulation
can be produced in several ways. Ultrasound waves are al-
most always produced using piezoelectric ceramics[7]. For
all devices the acoustic impedance of various layers must be
considered to either transmit acoustic energy or reflect it as
necessary.
The most common approach is a multilayer resonant sys-
tem, consisting of stacked layers, from bottom to top: trans-
ducer, coupling layer, fluid, and a reflecting layer. The thick-
ness of the layers must be tuned carefully to achieve reso-
nance. This dependence on geometry limits resonant systems’
manipulation capacity since the nodal positions of the acous-
tic field are fixed. Other approaches include using focused
ultrasound beams (first developed by Wu in 1991 [18]) in a
method similar to optical tweezers, or using a linear array of
transducers opposite a reflector. Linear arrays have been ap-
plied successfully in 300µm channels by Demore et al.[19].
The final approach, and the one applied in this project, is to
produce a standing wave using an opposed pair of transducers
emitting counter-propagating travelling waves. This has the
advantage of being unaffected by changes in the resonant fre-
quency of the chamber due to large numbers of particles in the
fluid[20]. One challenge is to eliminate reflection at the trans-
ducers, to avoid production of a resonant wave in addition to
the desired standing wave. Arbitrary positioning of the nodal
points by adjustment of the relative phases of the waves and
rapid variation of the field is possible even in a chamber sev-
eral wavelengths long. This is advantageous for fine control of
particles and also allows a larger working volume in compar-
ison to microfluidic resonant systems. While opposing trans-
ducers allow arbitrary nodal positioning, the traps are always
at half-wavelength separation and any phase variation affects
all traps simultaneously[21]. An early example of an opposing
transducer system was developed by Kozuka[22], with recent
work by Courtney et al. demonstrating manipulation in one
and two dimensions[21, 23]. Manipulation in two dimensions
is achieved by using two opposed pairs emitting at 90◦
to each
other, producing a grid-like series of nodes. One limiting fac-
tor in this technique is the frequency and impedance matching
of the opposed transducers. The closer in frequency the two
travelling waves are, the greater the amplitude of the stand-
ing wave created and the stronger the trapping. Impedance
matching ensures similar mechanical responses under load
from each transducer, so their resonances shift together[24].
Grinenko et al. have demonstrated the possibility of work-
ing with unmatched transducers by the application of acoustic
absorbers behind the transducers[25].
Acoustic streaming presents a problem for all manipula-
tion and trapping. This is caused by the bulk fluid absorbing
acoustic energy, leading to flow, which can force cells out of
the area of interest via drag forces and cause unwanted stress
on cells[26]. There are three forms of streaming: Eckart,
Schlichting and Rayleigh. Eckart streaming is the largest in
magnitude but is strongly influenced by the depth of fluid
and can be reduced significantly by working in shallower
fluids[27].
CHARACTERISING A DEVICE – EFFECTS ON CELL
VIABILITY AND MANIPULATION CAPABILITIES
Having constructed a functioning device for acoustic ma-
nipulation, it is necessary to characterise its capabilities and
impact on cells. The first step in any cell study is to main-
tain viability. There is large body of evidence that medical
ultrasound at low intensity has no significant impact on hu-
man tissue[28, 29]. While this is true for bulk tissues it may
3. 3
not hold true for individual cells or different cell types, so
each case must be considered individually. In general the
damaging effects of ultrasound are considered as thermal or
non-thermal. Thermal effects are problematic since most cells
have a suitable temperature range for proliferation of a few
degrees centigrade, thus heating can easily push the culture
out of this range. Fortunately thermal absorption by water in
the range of 1–10MHz, most commonly used for ultrasonic
acoustic trapping, is low. In the case of small volumes, di-
rect heat transfer from transducers can present issues, but this
can be mitigated with careful cooling of the transducers [30].
Temperature in acoustic devices can be tracked via fluores-
cence studies using Rhodamine B[11]. Using Rhodamine re-
moves the need for a physical thermocouple which would dis-
turb the acoustic field.
Non-thermal effects include stresses applied to cells by the
acoustic radiation force, streaming (see previous page) and
cavitation. Cavitation is generally negligible for the MHz fre-
quencies used in acoustic manipulation; it also requires nucle-
ating sites for bubble formation, so can be mitigated by use of
degassed water with few microscopic bubbles present[31].
Despite the potential for adverse effects, several studies
have demonstrated the viability of cells held in ultrasound
traps. Bazou et al. tested embryonic stem cells[26, 32], Hul-
str¨om COS-7 cells[33], Evander et al. yeast cells[11] and
Haake et al. HeLa cells[34]. Each group was working with
their own device, demonstrating that cells remain viable un-
der a variety of acoustic conditions. The simplest method for
quantifying the impact of trapping on cell viability is through
observations of cell membrane integrity using an optical mi-
croscope or cell-counting device. Several dyes exist which in-
crease the visibilty of damaged cells by either tracking active
metabolic processes or only penetrating ruptured cells[30].
A recently developed method for direct measurement of the
force uses optical tweezers. Particles are held in the optical
tweezers at a known position with known force, since optical
trapping has well–established parameters. The acoustic power
is increased until the particle escapes the optical trap. An ad-
vantage of this route is that it makes no assumptions about the
fluid or pressure field. Another route to measuring forces is
to apply particle image velocimetry as particles move towards
the nodal points in a field[24].
PROJECT PROGRESS
The aim of the project is to design and construct a
centimetre-scale ultrasound trap which maintains cell viabil-
ity, allows optical access for live imaging and can be sterilised
for reuse.
Initial design possibilities were suggested by Dr Berry and
Dr Barnes in the form of a centimetre-scale device developed
in the Biosciences group. This device worked with two pairs
of opposed piezoelectric transducers in a 3D printed mount
which is submerged in the cell–culture medium. This led to
difficulties with sterilisation and construction of the power
FIG. 1: The original device showing the circular mount holding the
transducers – this is then inserted into a petri–dish containing the
cell–culture.
supplies, since they are fed around the petri–dish cover. It
was also reported that the device struggled to maintain cell vi-
ability. However, as an initial device for developing skills and
testing construction methods it is proving useful.
Design of a new device and preliminary testing with the
original were carried out in tandem. Whatever final design is
chosen the piezoelectric crystals must be characterised care-
fully for optimal trapping. We tested the original device using
a Wayne-Kerr 6500b impedance analyser to locate the reso-
nances of the transducers. Using the resonant frequency is
vital to achieve maximum conversion of electrical to mechan-
ical power. Having characterised the device, we carried out
initial tests using flour as a cheap substitute for micro-beads.
The result was successful alignment of flour grains parallel to
the driven pair of transducers using a frequency of 6.915MHz,
as shown in Fig. 2. The larger clumps of flour were beyond
the capacity of the device to trap but the smaller particles are
seen aligned. These tests allowed us to gain experience with
the Olympus SZX-16 microscope being used for optical ob-
servations.
When developing a new device, the first decision was
whether to locate the transducers within the fluid medium,
for best transmission of acoustic energy, or outside the fluid
chamber for ease of sterilisation. It was decided that sepa-
rating the fluid and transducers would make sterilisation sim-
4. 4
FIG. 2: Flour-water suspension aligned using the initial device.
The thin lines of flour formed when the transducers were driven at
6.915MHz and 7.5 Vpp while the larger clumps were unaffected.
pler. Our first test–bed device, shown in Fig. 4 is based on
the work of Scholz et al., with a smaller fluid chamber[20].
It uses two opposed transducers and a central, square fluid
chamber mounted on a standard microscope slide using sili-
cone glue. It is hoped future iterations will provide phase con-
trol of individual transducers for 1D manipulation and even-
tually introduce an additional pair of transducers for 2D ma-
nipulation. The transducers will be held in position either us-
ing 3D printed x-shaped mounts, as in Fig. 4, or small com-
pression springs. Initial working sketches of a second gen-
eration device are shown in Fig.5 The first generation de-
vice has been produced in polymethyl methacrylate (PMMA)
acrylic and glass to test the acoustic properties of both mate-
rials. This involved producing 3D models of the device for
laser and water cutting. The water cutting was carried out in
the university workshops as it required specialist equipment.
The laser cutting took place on the student-accessible device
FIG. 3: The two initial devices - the upper is cut in glass, the lower
in acrylic.
FIG. 4: Schematic diagram of the new device, all dimensions are
in mm. The position of one mounted transducer is shown in blue,
the 3D printed mount in orange. The finished device will have a
symmetrical pair.
FIG. 5: Proposed layout for a device with two opposed pairs of trans-
ducers - the dimensions are currently the same as for the first iteration
device.
in the engineering department. With the help of Philip Bassin-
dale we learned to program this ourselves and will be able to
produce future designs without assistance. The glass device
has grooves cut for power supplies and we will add these to
the acrylic device before testing. With the transducers outside
the fluid chamber a coupling medium will be needed between
the transducer and the container. Initial tests will use commer-
cially available EE1295 ultrasound gel, since this is designed
to impedance match water–dominated tissue and our fluid will
be water based.
We will be working with human epithelial and corneal cells
which require containment level 1 procedures. The necessary
training is being provided by Dr Berry. We hope to be able
to produce our own cell cultures and suspensions of desired
concentrations for cell studies. Initial tests will be carried out
using fixed, dyed cells of the same type as will be used live
later in the project.
CONCLUSION
The potential of acoustic manipulation of live cells has been
well–established. Opposing transducer methods have been
used relatively little in biophysics but engineering applications
have shown them to have the precision and power required for
handling live cells. Non-contact manipulation of cells in this
way has the potential to provide targeted signalling molecule
5. 5
delivery to subgroups of cells in the same environment for di-
rect comparison.
ACKNOWLEDGEMENTS
Dr Barnes and Dr Berry for their support in planning and
initiating the project. Thanks must also go to John Rowden
and Philip Bassindale for their assistance in producing the
glass and laser-cut devices.
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