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We have succeeded in local and in-situ injection of reagent into a single plant cell by using the cavitation phenomenon of micro-bubbles. Micro-bubbles were generated electrically by a novel device called “micro-bubble injector”. This novel technology provides minimally invasive processing and high accessibility compared to conventional injection techniques which enable to inject to the material which have been difficult to be injected for a long time. This technology contribute to the biological and medical researches developments.

Patients in critical care with lung injuries require oxygenation, but current methods are not applicable for all situations. The most common method, Extracorporeal Membrane Oxygenation is an expensive procedure and requires highly trained staff. Respiratory Assist Catheters (RACs) could be used as an alternative because they do not place extra stress on the lungs, are easy to implement, cost-effective and are available for immediate use in clinical settings or in first aid situations. This paper describes experiments and simulations to evaluate the feasibility of intravenously oxygenating the blood using microbubbles. The tests included in vivo and ex vivo tests using animal models to investigate both the dissolution times of the microbubbles as well as the physiological effects of an intravenously placed device. Numerical simulations based on the dissolution rate of oxygen in venous blood were also completed. The results indicate that the dissolution times for the micro bubbles are too slow for the device to be successful in clinical practice.

This paper deals about the intravenous catheter measurement for position and micro bubble influence of the measurement accuracy. There was realized measurement chain for this purpose. The tested catheters and numerous measurements show the catheter parameter changes due the different position and the micro bubbles in the liquid.

Micro bubble was used as a pre-treatment process in the pilot experiment of treatment of slaughterhouse wastewater by contact oxidation system in the paper. The removal of COD, ammonia, SS and oil by micro bubble process in the treatment of slaughterhouse wastewater was investigated in the pilot experiment. The results showed that the removal efficiency of SS and oil of micro bubble was over 96% and 99% respectively. And in the long run experiment, the average removal efficiency of COD and ammonia was 40% and 37%, the removal amount of COD and ammonia by micro bubble process was 33% and 48% respectively in the removal amount of whole process, so the micro bubble process plays an important role in the pilot system.

Cavitation micro bubble enhances the permeability of cell membrane if the bubble is placed in the vicinity of the cell. Aiming at adhering micro bubbles to the target wall, a method by frequency sweep of ultrasonic pumping wave is proposed. Slow frequency decrease from fH to fL expands the aggregated bubbles to the surrounding target wall. Quick frequency return from fL to fH followed by the slow frequency decrease increases the amount of adhered bubbles to the target wall. Three dimensional numerical analyses are carried out by taking into account of the secondary Bjerknes forces between bubbles. Basic experiment is done using an ultrasonic contrast agent micro bubble.

Explosive evaporation occurs when a liquid is exposed to extremely high heat-fluxes. Within a few microseconds a bubble in the form vapour film is generated, followed by rapid growth due to the pressure impulse and finally the bubbles collapse. This effect, which already has proven its use in current inkjet printer technology, can be used to produce mechanical work. Here it will be utilised to deflect a 1 μm thick low-stress silicon-nitride membrane. Bubble nucleation and growth are studied with stroboscopic microscopy and membrane deflection is measured with a laservibrometer. Within a few microseconds the bubbles can produce a pressure of several bar resulting in a membrane deflection of micrometers and a membrane speed of more than 1 m/s.

Recently, we envisioned so called micro bubble tweezers where EWOD (electrowetting-on-dielectric) actuated bubbles can manipulate micro objects such as biological cells by pushing or pulling them. Besides, oscillating (shrinking and expanding) bubbles in the presence of ultrasonic wave act as a to deliver drugs and molecules into the cells. In this paper, as a great stride in our quest for micro bubble tweezers, we present (1) full realization of two critical bubble operations (generating of bubbles in an on-chip and on-demand manner and splitting of single bubbles) and (2) two possible applications of mobile bubbles oscillating under acoustic excitation (a mobile vortex generator and micro particle carrier).

By using on-chip lenses and fluidic operations to control focal length and direction of a laser beam, two kind of new concepts are proposed in the paper. One is a device to generate and control micro bubbles inside a microfluidic chip. Second is a new optical paths control method by microfluidic operation. To demonstrate the functionality of the optical paths control, the present method was utilized for optical tweezers applications.

Although microthermal bubble actuation has been applied in many MEMS/BioMEMS devices, little research work has been addressed the scaling of microbubble actuators. In this work, the fundamental investigation of the scaling effects of microbubble actuators is reported. Using a 1.66 ms-wide heating pulse, micro boiling in water was studied on various microbubble actuators, of which feature sizes range from 0.5 /spl mu/m to 70 /spl mu/m. We found that there existed a critical heater size (10 /spl mu/m), for which the boiling pattern with size below or above 10 /spl mu/m were quite different.

A mass-manufacturable endoskeletal micro bubble actuator has been developed and characterized. These pneumatically-actuated devices combine the desirable large deflections of balloon-type actuators with the preferentially-axial deflection of bellows type actuators to produce actuators capable of large deflections in axial directions. This kinematic stabilization is achieved by use of integrated "skeletons" - structures to support desired deflections and suppress unwanted deflections, which underlie the actuator "skin" - elastic structures to help the extended actuator recoil to its original shape. The actuators have been fabricated and characterized, as well as compared with pure-bubble actuators (skin only) and pure-bellows actuators (skeleton only) of the same materials and dimensions. Pure-bubble actuators demonstrated unwanted omni-directional inflation. Pure-bellows actuators demonstrated unstable and irreversible deformation during extension. In contrast, endoskeletal microbubble actuators of 2.6 mm diameter have achieved reversible axial extensions of approximately 0.9 mm.

A novel method for micro bubble manipulation by ultrasonic waves is proposed. This method uses seed bubbles in order to manipulate the target bubbles. First, if the seed bubbles are introduced into an incident ultrasonic wave field, they start to oscillate, radiating secondary ultrasonic waves around them. These waves produce Bjerknes force between the bubbles. This produces seed bubble aggregation with a certain size. Then, the target bubbles are introduced, the Bjerknes force between the aggregated seed bubbles and the target bubbles trap the target bubbles, producing a bi-layer bubble mass of (inner layer: seed bubbles, outer layer: target bubbles). Experiments are carried out using bubbles with PVC shells. It is observed that the target bubbles, which are not trapped when they flow into the ultrasonic wave field, are trapped as a bi-layer bubble mass by the proposed method.

An interest in plausible mechanisms for significant acoustic impact on some species of marine mammals at receive levels significantly below that currently anticipated to cause direct physical trauma has arisen in response to questions of how the operation of sonars may have contributed to mass beaching events of beaked whales. Resonance in cavities and other specific structures was at one time proposed as a mechanism, but after some scrutiny this now appears unlikely. Rectified diffusion was posed as another candidate, but has been demonstrated to be significant only at relatively high pressure levels, exceeding receive levels anticipated in observed beaching circumstances. We examine an alternative proposition; that pre-existing micro-bubbles that are normally stabilized and which do not normally permit gas exchange across their walls can be acoustically activated so that continued growth is supported through static diffusion from super-saturated tissues in the absence of an acoustic field. The proposed mechanism would explain why micro bubbles (believed to be normally present in mammalian tissues) do not grow and cause decompression sickness (DCS) in healthy deep divers with super-saturated tissues, why these micro bubbles do not collapse under the Laplace pressure exerted by surface tension in unsaturated tissues, and why long-duration, deep diving cetaceans such as beaked whales appear to be particularly vulnerable to anthropogenic acoustic exposures. Numerical results for bubble growth modelled according to the treatments of Crum and Mao under tissue super-saturations of 200-300% (an appropriate range for deep-diving marine mammals on surfacing) show that if micro-bubble gas exchange could be activated acoustically, even by only a very brief exposure, this would result in subsequent bubble growth by static gas diffusion so that within 10 minutes their size would be sufficient to cause symptoms of decompression sickness (DCS)

We report a series of micro air bubble manipulations (transporting, merging and eliminating of air bubbles) in two-dimensional microchannels filled with a water solution. Air bubbles (~500 nano liters in volume) are driven by electrowetting-on-dielectric (EWOD) principle. By sequentially energizing an array of electrodes covered with dielectric layers, air bubbles can be transported along a programmed path, merged into a single larger one, and eliminated out of a bulk water solution. This bubble manipulation technique can be applied to efficiently handle micro objects. As a proof of concept, we successfully demonstrate in a millimeter scale that a fish egg and a sesame husk are attached to an air bubble and then driven by the bubble in a programmed way. The moving air bubble can push and pull the attached objects of which surface is hydrophilic or hydrophobic. This handling technique will bring a novel, versatile, cost-effective, high throughput tool, enabling us to efficiently transport, trap, and isolate individual micro bio-entities such as cells, functional particles and possibly molecules

To investigate viscosity effects on dynamic behavior of the micro bubble actuator under pulse heating, sucrose was added in the single-stranded DNA (ssDNA) solution to change its viscosity. It was found that a distinct retardation effect on the motion of the micro bubble was observed especially at high viscosities. It was also observed that the addition of the sucrose led to an increase of the electric power input required for incipient bubble nucleation. Based on thermodynamics consideration and a simple model for nucleus formation in ssDNA solution with the addition of sucrose, an analysis on bubble nucleation work was carried out and the results are consistent with experimental data.

When the micro-bubble oscillates under the ultrasonic wave, the bubble radiates secondary waves around it. This wave generates secondary Bjerknes force between the neighboring bubbles and the force assists inherent bubble movements such as bubble aggregation inside the ultrasonic wave field. In this paper, a novel technique to characterize the secondary ultrasonic wave from the bubbles is proposed. This method is based on the observation of fringe like pattern produced around the bubble of interest. This pattern is produced by micro bubbles which are trapped inside the interference wave field of incident wave and the secondary wave. The experiments are carried out by an ultrasonic wave contrast agent "Levovist" (SCHERING A.G. Germany). The fringe like patterns are observed for relative large aggregated bubbles.

The Gas-filled Micro Void Particle Detector is based on gas-filled micro voids placed in an external electric field. This detector is presenting common features between solid state and gas filled devices as internal amplification, unlimited size and shape, dense, high efficiency parallax reducing structure. The gas filling in the void and/or the wall of the micro void serves as radiation detector. The working principle was tested on syntactic foam composed of glass micro bubbles embedded in an epoxy matrix.