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.

/pdf/microscale-acoustofluidics-microfluidics-driven-via-5bet39j13p.pdf

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

This book gives the fundamental principles and device design techniques for surface acoustic wave filters. It covers the devices in widespread use today: bandpass and pulse compression filters, correlators and non-linear convolvers and resonators. The newest technologies for low bandpass filters are fully covered such as unidirectional transducers, resonators in impedance element filters, resonators in double-mode surface acoustic wave filters and transverse-coupled resonators using waveguides.The book covers the theory of acoustic wave physics, the piezoelectric effect, electrostatics at a surface, effective permittivity, piezoelectric SAW excitation and reception, and the SAW element factor. These are the main requirements for developing quasi-static theory, which gives a basis for the non-reflective transducers in transversal bandpass filters and interdigital pulse compression filters. It is also needed for the reflective transducers used in the newer devices. It is a thorough revision of a classic on surface acoustic wave filters first published in 1985 and still in print. It uniquely combines easy-to-understand principles with practical design techniques for all the devices in widespread use today. It includes complete coverage of all the latest devices which are key to mobile phones, TVs and radar systems; and, a new foreword by Sir Eric Albert Ash.

Surface Acoustic Wave Filters: With Applications to Electronic Communications and Signal Processing

The characteristics of one-port aluminum nitride (AlN) Lamb wave resonators utilizing the lowest-order symmetric mode with electrically open, grounded, and floating bottom electrode configurations are theoretically and experimentally investigated in this paper. Finite element analysis is performed to take an insight into the static capacitance characteristics of the AlN Lamb wave resonators with various bottom surface conditions. Without sacrificing the transduction efficiency, the floating bottom electrode is capable of reducing the static capacitance in the AlN thin plate and then promotes an efficient improvement in the effective coupling coefficient (k2eff). In addition, in comparison with the grounded bottom electrode, the employment of the floating bottom electrode offers simple fabrication processes for the micromachined Lamb wave resonators. Experimentally, the AlN Lamb wave resonators without the bottom electrode exhibit an average loaded quality factor (Q) as high as 2676 at the series resonance frequency, but a low average k2eff of 0.19%. On the contrary, the Lamb wave resonators with the electrically floating bottom electrode show the largest average k2eff up to 1.13% among the three topologies but a low average loaded Q of 800 at the series resonance frequency. In contrast to the floating bottom electrode, the Lamb wave resonators with the electrically grounded bottom electrode show a smaller average k2eff of 0.78% and a similar average loaded Q of 758 at the series resonance frequency.

Micromachined One-Port Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode

We describe the fabrication of a surface acoustic wave (SAW) atomizer and show its ability to generate monodisperse aerosols and particles for drug delivery applications. In particular, we demonstrate the generation of insulin liquid aerosols for pulmonary delivery and solid protein nanoparticles for transdermal and gastrointestinal delivery routes using 20 MHz SAW devices. Insulin droplets around 3 µm were obtained, matching the optimum range for maximizing absorption in the alveolar region. A new approach is provided to explain these atomized droplet diameters by returning to fundamental physical analysis and considering viscous-capillary and inertial-capillary force balance rather than employing modifications to the Kelvin equation under the assumption of parametric forcing that has been extended to these frequencies in past investigations. In addition, we consider possible mechanisms by which the droplet ejections take place with the aid of high-speed flow visualization. Finally, we show that nanoscale protein particles (50‐100 nm in diameter) were obtained through an evaporative process of the initial aerosol, the final size of which could be controlled merely by modifying the initial protein concentration. These results illustrate the feasibility of using SAW as a novel method for rapidly producing particles and droplets with a controlled and narrow size distribution.

https://users.monash.edu/~lyeo/Dr_Leslie_Yeo/SAW_Atomisation_files/Alvarez_Nanotechnology_19_455103_2008.pdf

Rapid generation of protein aerosols and nanoparticles via surface acoustic wave atomization

Graphene oxide as sensitive layer in Love-wave surface acoustic wave sensors for the detection of chemical warfare agent simulants

1. Bulk Acoustic and Surface Acoustic Waves.- 2. Grating.- 3. Interdigital Transducers.- 4. Transversal Filters.- 5. Resonators.- 6. Selection of Substrate Material.- 7. Coupling-of-Modes Theory.- 8. Simulation of SH-type SAW Devices.- A. Physics of Acoustic Waves.- A.1 Elasticity of Solids.- A.2 Piezoelectricity.- A.3 Surface Acoustic Waves.- A.4 Effective Acoustic Admittance Matrix and Permittivity.- A.5 Acoustic Wave Properties in 6mm Materials.- A.5.1 Rayleigh-Type SAWs.- A.5.2 Effective Permittivity for BGS Waves.- A.5.3 Effective Acoustic Admittance Matrix.- A.6 Wave Excitation.- A.6.1 Integration Path.- A.6.2 Electrostatic Coupling.- A.6.3 BGS Wave Excitation.- A.6.4 SSBW Excitation.- References.- B. Analysis of Wave Propagation on Grating Structures.- B.1 Summary.- B.2 Metallic Gratings.- B.2.1 Blotekjr's Theory for Single-Electrode Gratings.- B.2.2 Wagner's Theory for Oblique Propagation.- B.2.3 Aoki's Theory for Double-Electrode Gratings.- B.2.4 Extension to Triple-Electrode Gratings.- B.3 Analysis of Metallic Gratings with Finite Thickness.- B.3.1 Combination with Finite Element Method.- B.3.2 Application to Extended Blotekjaer Theories.- B.4 Wave Excitation and Propagation in Grating Structures.- B.4.1 Effective Permittivity for Grating Structures.- B.4.2 Evaluation of Discrete Green Function.- B.4.3 Delta-Function Model.- B.4.4 Infinite IDTs.- References.

研也橋本

Papers

Surface acoustic wave devices in telecommunications : modelling and simulation

研也 橋本

Papers

Surface acoustic wave devices in telecommunications : modelling and simulation

研也橋本