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1.
Opt Lett ; 39(13): 3732-5, 2014 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-24978723

RESUMEN

We report on the optical excitation and detection of resonant microbubble oscillations. Optically absorbing nanoparticles were attached to the shell of a lipid-encapsulated microbubble, allowing for optical pulsing to photothermally drive the microbubble into resonance. A modified optical microscope was used to track the bubble wall radius as a function of time using light scattering. The microbubble response from a nanosecond laser pulse was measured, and the eigenfrequency and vibrational amplitude were determined and compared to theory. The ability to optically drive microbubble oscillations may have applications in basic studies of bubble dynamics and biomedical imaging and therapy.


Asunto(s)
Nanopartículas del Metal , Microburbujas , Materiales Biocompatibles Revestidos , Medios de Contraste , Oro , Rayos Láser , Nanopartículas del Metal/ultraestructura , Microscopía Acústica/instrumentación , Fenómenos Ópticos , Tamaño de la Partícula , Técnicas Fotoacústicas/instrumentación
2.
J Acoust Soc Am ; 127(4): 2252-61, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20370006

RESUMEN

Needle-free injection is a novel technique for transdermal drug and vaccine delivery, the efficacy of which depends on the number density and mean penetration depth of particles beneath the skin. To date, these parameters have been assessed optically, which is time-consuming and unsuitable for use in vivo. The present work describes the development of a scanning acoustic microscopy technique to map and size particle distributions following injection. Drug particles were modeled using a polydisperse distribution of polystyrene spheres, mean diameter 30.0 mum, and standard deviation 16.7 mum, injected into agar-based tissue-mimicking material, and later, as polydisperse stainless steel spheres, mean diameter 46.0 mum, and standard deviation 13.0 mum, injected both into agar and into porcine skin. A focused broadband immersion transducer (10-75 MHz), driven in pulse-echo mode, was scanned over the surface of the injected samples. Recorded echo signals were post-processed to deduce particle penetration depth (30-300 mum). Furthermore, post-injection size distribution of the spheres was calculated using a novel, automated spectral analysis technique. Experimental results were validated optically and found to predict penetration depth and particle size accurately. The availability of simultaneous particle penetration depth and particle size information makes it possible for the first time to optimize particle design for specific drug delivery applications.


Asunto(s)
Sistemas de Liberación de Medicamentos , Microscopía Acústica , Poliestirenos/química , Piel , Acero Inoxidable/química , Administración Cutánea , Agar/química , Algoritmos , Animales , Sistemas de Liberación de Medicamentos/instrumentación , Inyecciones a Chorro , Microscopía Acústica/instrumentación , Tamaño de la Partícula , Permeabilidad , Poliestirenos/administración & dosificación , Reproducibilidad de los Resultados , Procesamiento de Señales Asistido por Computador , Análisis Espectral , Porcinos , Transductores
3.
J Nanosci Nanotechnol ; 6(1): 72-6, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16573072

RESUMEN

We derived a simple method to fabricate STM-SNOM hybrid probes obtained from commercial cheap communication optical fibers. The tips are fabricated by a methodology that combines two well-known techniques: the selective attack by a buffered solution and the protected layer chemical etching, in a single new one-step technique. The tailored probes are then sputtered by metal and mounted on a STM setup. The usual difficulties of integrating the optical fiber in the STM head are solved originally with a particular home made mount described in details. We will show that the resulting probes reach atomic resolution on both vertical and horizontal scale, and that the optical imaging is free of artifacts and satisfactory with a lateral resolution in the order of lamda/20, as far as we know the finest resolution obtained with a system based on a hybrid fiber probe. We believe that our methodology is very interesting for its simplicity of realization and for the good resolving power in both SNOM and STM modes.


Asunto(s)
Microscopía de Fuerza Atómica/métodos , Diseño de Equipo , Látex/química , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Microscopía de Fuerza Atómica/instrumentación , Nanoestructuras/química , Sensibilidad y Especificidad
4.
Ann Biomed Eng ; 44(3): 649-66, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26471785

RESUMEN

At the intersection of life sciences, materials science, engineering, and medicine, regenerative medicine stands out as a rapidly progressing field that aims at retaining, restoring, or augmenting tissue/organ functions to promote the human welfare. While the field has witnessed tremendous advancements over the past few decades, it still faces many challenges. For example, it has been difficult to visualize, monitor, and assess the functions of the engineered tissue/organ constructs, particularly when three-dimensional scaffolds are involved. Conventional approaches based on histology are invasive and therefore only convey end-point assays. The development of volumetric imaging techniques such as confocal and ultrasonic imaging has enabled direct observation of intact constructs without the need of sectioning. However, the capability of these techniques is often limited in terms of penetration depth and contrast. In comparison, the recently developed photoacoustic microscopy (PAM) has allowed us to address these issues by integrating optical and ultrasonic imaging to greatly reduce the effect of tissue scattering of photons with one-way ultrasound detection while retaining the high optical absorption contrast. PAM has been successfully applied to a number of studies, such as observation of cell distribution, monitoring of vascularization, and interrogation of biomaterial degradation. In this review article, we highlight recent progress in non-invasive and volumetric characterization of biomaterial-tissue interactions using PAM. We also discuss challenges ahead and envision future directions.


Asunto(s)
Materiales Biocompatibles , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Animales , Humanos
5.
J Biomed Mater Res B Appl Biomater ; 73(1): 29-34, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15672390

RESUMEN

The micromechanical elastic properties of potential bone-graft materials were compared with that of the human mandible. Six different potential bone-replacement materials were used: Bio-Oss (Osteohealth), OsteoGraf/N-700 (Ceramed), Pepgen P15 (Ceramed), Interpore200 (Interpore Cross International), Allogro (Ceramed), and Dynagraft (GenSci Dental). As a control, mandibular cortical bone was obtained from a 17-year-old woman. Micromechanical elastic property analysis was obtained with the use of a UH3 scanning acoustic microscope (Olympus Co., Tokyo, Japan) (SAM) at 400 MHz in the burst mode. Each sample was measured at three areas. The data were analyzed statistically by SPSS (SPSS, Inc.) with the use of the Student t test. In human bone, the reflection coefficients r of the x dimension (r = 0.75 +/- 0.01) was statistically higher than those of the y (0.72 +/- 0.05) and the z (0.72 +/- 0.01) directions. The order of stiffness magnitude was found to be Pepgen (r = 0.73 +/- 0.05) >/= OsteoGraf (0.72 +/- 0.03) > Bio-Oss (0.71 +/- 0.02) > Interpore (0.69 +/- 0.10) > Dynagraft (0.43 +/- 0.05) > Allogro (0.36 +/- 0.04). For these samples, Interpore alone showed a large deviation in properties in the same specimen. With regard to the elastic properties solely, bone-grafting materials made from bovine or processed marine coral appear to be reasonable choices as graft materials.


Asunto(s)
Materiales Biocompatibles/química , Sustitutos de Huesos/química , Trasplante Óseo/métodos , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Acústica , Adolescente , Animales , Antozoos , Huesos/metabolismo , Calibración , Bovinos , Diseño de Equipo , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Mandíbula/patología , Modelos Estadísticos , Estrés Mecánico , Propiedades de Superficie
6.
J Biomed Mater Res A ; 66(1): 120-8, 2003 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-12833438

RESUMEN

In a previous study, we reported the upper limit of Young's modulus of the unprotected protein at the dentin/adhesive interface to be 2 GPa. In this study, to obtain a more exact value of the moduli of the components at the d/a interface, we used demineralized dentin collagen with and without adhesive infiltration. The prepared samples were analyzed using micro-Raman spectroscopy (micro RS) and scanning acoustic microscopy (SAM). Using an Olympus UH3 SAM (Olympus Co., Tokyo), measurements were recorded with a 400 MHz burst mode lens (120 degrees aperture angle; nominal lateral resolution, 2.5 microm). A series of calibration curves were prepared using the relationship between the ultrasonically measured elastic moduli of a set of known materials and their SAM response. Finally, both the bulk and bar wave elastic moduli were computed for a set of 13 materials, including polymers, ceramics, and metals. These provided the rationale for using extensional wave measurements of the elastic moduli as the basis for extrapolation of the 400 MHz SAM data to obtain Young's moduli for the samples: E = 1.76 +/- 0.00 GPa for the collagen alone; E = 1.84 +/- 0.65 GPa for the collagen infiltrated with adhesive; E = 3.4 +/- 1.00 GPa for the adhesive infiltrate.


Asunto(s)
Bisfenol A Glicidil Metacrilato/farmacología , Colágeno/química , Recubrimientos Dentinarios/farmacología , Dentina/química , Calibración , Colágeno/aislamiento & purificación , Elasticidad , Diseño de Equipo , Humanos , Microscopía Acústica/instrumentación , Microscopía Acústica/normas , Minerales , Diente Molar , Espectrometría Raman
7.
Artículo en Inglés | MEDLINE | ID: mdl-12046930

RESUMEN

An acoustic microscope operating with impulse excitation has been used to perform measurements of the Rayleigh wave velocity by measuring the time difference between the direct reflected signal and the Rayleigh wave signal. The accuracy and precision of the methodology have been examined by performing measurements at a single location on an elastically isotropic sample of E6 glass. The accuracy of the Rayleigh wave velocity measurement has been determined to be better than 0.5%. The measured Rayleigh wave velocity of (3035+/-5) m/s differs by 0.3% from measurements reported in the literature for a similar sample, using two different techniques. The methodology has been extended to acquire the Rayleigh wave velocity while raster scanning the sample to develop a quantitative velocity image. The background noise in the Rayleigh wave velocity image has been investigated by mapping the velocity on elastically isotropic E6 glass. Possible reasons for background noise in the images is discussed. The methodology has been extended to acquire quantitative Rayleigh wave velocity images on Ti-6Al-4V. The contrast in the images is attributed to the variation of the Rayleigh wave velocity in individual grains or regions. Applicability of the technique to investigate crystallographic texture in materials is discussed.


Asunto(s)
Cristalografía/métodos , Vidrio/química , Ensayo de Materiales/métodos , Microscopía Acústica/métodos , Modelos Teóricos , Titanio/química , Aleaciones , Cristalografía/instrumentación , Ensayo de Materiales/instrumentación , Microscopía Acústica/instrumentación
8.
Artículo en Inglés | MEDLINE | ID: mdl-14561032

RESUMEN

Optical generation of ultrasound is a promising alternative to piezoelectricity for high-frequency arrays. An array element is defined by the size and location of a laser beam focused on a suitable surface. Optical generation using the thermoelastic effect has traditionally suffered from low conversion efficiency. We previously demonstrated an increase in conversion efficiency of nearly 20 dB with an optical absorbing layer consisting of a mixture of polydimethylsiloxane (PDMS) and carbon black spin coated onto a glass microscope slide. Radiation pattern measurements with an 85 MHz spherically focused transducer indicated an array element size of 20 microm. These measurements lacked the spatial resolution required to reveal fine details in the radiated acoustic field. Here we report radiation pattern measurements with a 5-microm spatial sampling, showing that the radiated acoustic field is degraded by leaky Rayleigh waves launched from the PDMS/glass interface. We demonstrate that replacing the glass with a clear PDMS substrate eliminates the leaky Rayleigh waves, producing a broad and smooth radiation pattern suitable for a two-dimensional (2-D) phased array operating at frequencies greater than 50 MHz.


Asunto(s)
Dimetilpolisiloxanos/efectos de la radiación , Rayos Láser , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Siliconas/efectos de la radiación , Transductores , Simulación por Computador , Elasticidad , Diseño de Equipo , Estudios de Factibilidad , Modelos Teóricos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Conductividad Térmica
9.
Appl Opt ; 47(4): 561-77, 2008 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-18239717

RESUMEN

A multiwavelength backward-mode planar photoacoustic scanner for 3D imaging of soft tissues to depths of several millimeters with a spatial resolution in the tens to hundreds of micrometers range is described. The system comprises a tunable optical parametric oscillator laser system that provides nanosecond laser pulses between 600 and 1200 nm for generating the photoacoustic signals and an optical ultrasound mapping system based upon a Fabry-Perot polymer film sensor for detecting them. The system enables photoacoustic signals to be mapped in 2D over a 50 mm diameter aperture in steps of 10 microm with an optically defined element size of 64 microm. Two sensors were used, one with a 22 microm thick polymer film spacer and the other with a 38 mum thick spacer providing -3 dB acoustic bandwidths of 39 and 22 MHz, respectively. The measured noise equivalent pressure of the 38 microm sensor was 0.21 kPa over a 20 MHz measurement bandwidth. The instrument line-spread function (LSF) was measured as a function of position and the minimum lateral and vertical LSFs found to be 38 and 15 microm, respectively. To demonstrate the ability of the system to provide high-resolution 3D images, a range of absorbing objects were imaged. Among these was a blood vessel phantom that comprised a network of blood filled tubes of diameters ranging from 62 to 300 microm immersed in an optically scattering liquid. In addition, to demonstrate the applicability of the system to spectroscopic imaging, a phantom comprising tubes filled with dyes of different spectral characteristics was imaged at a range of wavelengths. It is considered that this type of instrument may provide a practicable alternative to piezoelectric-based photoacoustic systems for high-resolution structural and functional imaging of the skin microvasculature and other superficial structures.


Asunto(s)
Acústica/instrumentación , Algoritmos , Diagnóstico por Imagen de Elasticidad/instrumentación , Imagenología Tridimensional/instrumentación , Interferometría/instrumentación , Microscopía Acústica/instrumentación , Reconocimiento de Normas Patrones Automatizadas/métodos , Diagnóstico por Imagen de Elasticidad/métodos , Diseño de Equipo , Análisis de Falla de Equipo , Aumento de la Imagen/instrumentación , Aumento de la Imagen/métodos , Imagenología Tridimensional/métodos , Interferometría/métodos , Membranas Artificiales , Microscopía Acústica/métodos , Óptica y Fotónica/instrumentación , Fantasmas de Imagen , Polímeros , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Transductores
10.
J Mater Sci Mater Med ; 18(4): 629-33, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17546424

RESUMEN

Micromechanical properties of human mandibular trabecular bone, with particular interest to any site differences were investigated. A mandible was harvested from a 66 year-old female cadaver free from bone disease. It was embedded in PMMA, cut into 2mm sections and polished. Micromechanical property measurements were obtained using the UH3 Scanning Acoustic Microscope (SAM) (Olympus Co., Tokyo, Japan) at 400MHz in the burst mode. 6 vertical slices from the right and 6 horizontal slices from the left were chosen. In each of the 12 samples, 3 points were measured; first in the center, the other 2 from the margins. Data were analyzed statistically by SPSS (SPSS, Inc.) using Student's t-test. The average value of reflection coefficient r is 0.58+/-0.079 with the range from 0.46 to 0.64; E=25.0+/-5.64 GPa. There is no significant difference in properties in the osteonal direction of related cortical bone and those found between the marginal area and center areas. The average value of r from the right side, 0.60+/-0.07, is statistically higher than the average value of from the left side, 0.56+/-0.07. Micromechanical properties of both mandibular trabecular and cortical bone have almost the same values.


Asunto(s)
Huesos/fisiología , Huesos/ultraestructura , Mandíbula/anatomía & histología , Mandíbula/ultraestructura , Microscopía Acústica/instrumentación , Microscopía Acústica/métodos , Anciano , Elasticidad , Femenino , Humanos , Mandíbula/fisiología
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