[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Sensitive optical biosensors for unlabeled targets: a review.

This article reviews acoustic microfiuidics: the use of acoustic fields, principally ultrasonics, for application in microfiuidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature.

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Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Towards integrated and sensitive surface plasmon resonance biosensors: a review of recent progress.

This review presents an overview of 20 years of worldwide development in the field of biosensors based on special types of surface acoustic wave (SAW) devices that permit the highly sensitive detection of biorelevant molecules in liquid media (such as water or aqueous buffer solutions). 1987 saw the first approaches, which used either horizontally polarized shear waves (HPSW) in a delay line configuration on lithium tantalate (LiTaO3) substrates or SAW resonator structures on quartz or LiTaO3 with periodic mass gratings. The latter are termed “surface transverse waves” (STW), and they have comparatively low attenuation values when operated in liquids. Later Love wave devices were developed, which used a film resonance effect to significantly reduce attenuation. All of these sensor approaches were accompanied by the development of appropriate sensing films. First attempts used simple layers of adsorbed antibodies. Later approaches used various types of covalently bound layers, for example those utilizing intermediate hydrogel layers. Recent approaches involve SAW biosensor devices inserted into compact systems with integrated fluidics for sample handling. To achieve this, the SAW biosensors can be embedded into micromachined polymer housings. Combining these two features will extend the system to create versatile biosensor arrays for generic lab use or for diagnostic purposes.

Surface acoustic wave biosensors: a review

For a multimode-optical-fiber surface plasmon resonance (SPR) sensor with a gold film supporting surface plasmon waves (SPWs), we have investigated the effects of gold thickness on sensor performance experimentally to find the optimal thickness when a white-light source is used. It is found that the sensor with a thickness of around 65 nm enables most precise measurement of a resonance wavelength and gives relatively high sensitivity, which is 1557 nm/RIU in the refractive index range of 1.333–1.3469. Also, we have confirmed that a simulation model based on meridional rays cannot explain the minimum reflectance of SPR spectra for values below 0.5.

Effects of gold film thickness on spectrum profile and sensitivity of a multimode-optical-fiber SPR sensor

In this paper, we describe a novel atomization system using surface acoustic wave (SAW) devices. The SAW radiates its energy into a liquid, if the liquid is loaded on the SAW propagating surface. The various liquid motions, such as vibration, flow and droplet formation, due to interaction between SAW and liquid are called SAW streaming. The liquid dynamics depends on the SAW input power. First, the relationships between input voltage to the SAW device and water dynamics are observed. For atomization, an input voltage larger than 30 VP-P is required. Second, a stable method of generating a mist is discussed. The thin liquid layer plays an important role in continuous mist generation. The fundamental properties, such as the angle and height of mist, are measured using a filter paper to keep a thin liquid layer on the surface. We also demonstrate the control of mist direction with an electrostatic field. Based on these fundamental experiments, a practical atomization system is designed and performed.

https://iopscience.iop.org/article/10.1143/JJAP.43.2987/pdf

Development of novel atomization system based on SAW streaming

The performance of a surface plasmon resonance (SPR) sensor depends on its design properties. In this paper, we described, both theoretically and experimentally, the role of the prism material in sensor design. The analyses were carried out by employing three prisms of different refractive indices and the reflection spectra were studied under the angular interrogation mode. The results proved that the choice of prism material can tailor the resonance condition and thus can effectively tune the working region of the sensor. Also, the experimental value of angular sensitivity increased from 94.46°/RIU to 204.41°/RIU on changing the refractive index of the prism from 1.597 to 1.456, without changing the other parameters. The variation of the angular sensitivity was in accordance with the analytical and numerical results. The dynamic range decreased and the full width at half maximum (FWHM) of the reflection spectra increased as the refractive index of the prism was lowered, thereby affecting the sensor's performance.

Tuning and sensitivity enhancement of surface plasmon resonance sensor

In this paper, we present a liquid-droplet-heating system using a surface acoustic wave (SAW) device. When liquid is placed on a Rayleigh-SAW-propagating surface, a longitudinal wave is radiated into the liquid. If the SAW amplitude increases, the liquid shows non-linear dynamics, such as vibrating, streaming, small droplet flying, and atomizing. This phenomenon is well known as SAW streaming. The liquid temperature is measured during the longitudinal wave radiation and found to increase. First, the mechanism of the liquid-heating effect is discussed on the basis of experimental results. The surface electrical condition is changed to investigate the effect of dielectric heating. The obtained results indicate that the radiated longitudinal wave causes liquid heating and the dielectric heating effect does not. Second, the fundamental properties of the liquid temperature are measured by varying the applied voltage, duty factor, and liquid viscosity. The liquid temperature is found to be proportional to the duty factor and the square of the applied voltage. Therefore, the liquid temperature can be controlled by these applied signals. Also, by using highly viscous solutions, the liquid temperature is increased to more than 100 °C. Moreover, for chemical applications, the possibility of periodic temperature control is tested by varying the duty factor. The obtained results strongly suggest that an efficient thermal cycler is realized. A novel application of the SAW device is proposed on the basis of SAW streaming.

/pdf/development-of-temperature-control-system-for-liquid-droplet-1zgmhexhb4.pdf

Development of temperature-control system for liquid droplet using surface Acoustic wave devices

Acoustic wave sensors are highly sensitive in detecting the properties of solid or fluid materials in contact with their surfaces, including the surface mass change, liquid density, liquid viscosity and electrical conductivity. In this paper, primarily, the commonly used acoustic wave sensors are reviewed and their mass sensitivities are compared. The fundamentals of the sensing system using the shear horizontal surface acoustic wave (SH-SAW) sensor on a 36° rotated Y-cut X-propagating LiTaO3 are described. Since the high sensitivity of the electrical perturbation is a significant advantage of the SH-SAW sensor, its applications based on acoustoelectric interaction are also presented.

https://iopscience.iop.org/article/10.1143/JJAP.43.2799/pdf

Jun Kondoh

Papers

Effects of gold film thickness on spectrum profile and sensitivity of a multimode-optical-fiber SPR sensor

Development of novel atomization system based on SAW streaming

Tuning and sensitivity enhancement of surface plasmon resonance sensor

Development of temperature-control system for liquid droplet using surface Acoustic wave devices

Surface Acoustic Wave Sensors