
Akitoshi OkinoInstitute of Science Tokyo
Akitoshi Okino
Doctor of Engineering
About
235
Publications
21,683
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1,931
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Introduction
Atmospheric Plasma Sources and Applications
Additional affiliations
October 2006 - January 2007
October 1998 - October 1999
April 2011 - present
Education
April 1991 - March 1994
April 1989 - March 1991
April 1985 - March 1989
Publications
Publications (235)
In this study, atmospheric nonequilibrium plasmas were generated with six gas species using a multi-gas plasma jet. Singlet oxygen, OH radicals, H radicals, and NO radicals, in reaction with a solution interface, were measured using electron spin resonance. Carbon dioxide plasma generated the largest amount (90 µM) of singlet oxygen at 30 s, and ar...
Protein introduction into cells is more difficult in plants than in mammalian cells, although it was reported that protein introduction was successful in shoot apical meristem and leaves only together with a cell-penetrating peptide. In this study, we tried to introduce superfolder green fluorescent protein (sGFP)-fused to adenylate cyclase as a re...
In this study, plasma gas species and temperature were varied to evaluate the reactive species produced and the bactericidal effect of plasma. Nitrogen, carbon dioxide, oxygen, and argon were used as the gas species, and the gas temperature of each plasma was varied from 30 to 90 °C. Singlet oxygen, OH radicals, hydrogen peroxide, and ozone generat...
The aim of the study was to design and build a multi-gas temperature-controllable plasma jet that can control the gas temperature of plasmas with various gas species, and evaluated its temperature control performance. In this device, a fluid at an arbitrary controlled temperature is circulated through the plasma jet body. The gas exchanges heat wit...
Previously, we developed a technique to introduce a superfolder green fluorescent protein (sGFP) fusion protein directly into plant cells using atmospheric-pressure plasma. In this study, we attempted genome editing using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9) system using this protein in...
An air-cooling torch was developed for argon-based inductively coupled plasma mass spectrometry (ICP-MS). The plasma gas aperture-width was decreased to 0.5 mm to permit the ignition of argon plasma at an RF power of 800 W with a plasma gas of 8.0 L/min. A stable argon plasma was achieved at an RF power up to 1,600 W by introducing 20 L/min of air...
Liposome lipid peroxidation induced by cold atmospheric pressure plasma jet (CAPPJ) irradiation was investigated. The formation of thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation final products, as a function of irradiation was observed. Lipid radicals, peroxidation reaction intermediates generated by CAPPJ irrad...
We report a deposition method of a polymer thin film on the silver surface of a surface plasmon sensor for preventing sensitivity degradation in refractive index measurements due to poor chemical stability of the silver. The deposition of a poly(methyl methacrylate) (PMMA) thin film with a ∽15-nm thickness was conducted by employing a spin coating...
Dielectric barrier discharge (DBD)-based technology is considered a promising alternative for controlling indoor air pollutants. However, its limited processing capacity and lack of design techniques have restricted its use in practical applications. This paper introduces a methodology for designing upscaled DBD reactors with a processing capacity...
Wide-bandgap gallium nitride (GaN)-based semiconductors offer significant advantages over traditional Si-based semiconductors in terms of high-power and high-frequency operations. As it has superior properties, such as high operating temperatures, high-frequency operation, high breakdown electric field, and enhanced radiation resistance, GaN is app...
Methicillin-resistant Staphylococcus aureus (MRSA) often causes serious infections in hospitals. Vancomycin is widely accepted as the standard therapy for MRSA infection, but its widespread use has resulted in the generation of vancomycin-resistant S. aureus (VRSA). To reduce the potential risk of MRSA and VRSA emergence in aquatic environments, we...
We used cold atmospheric pressure plasma jet to examine in detail ¹O2 generation in water. ESR with 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide, a secondary amine probe, was used for the detection of ¹O2. Nitroxide radical formation was detected after cold atmospheric pressure plasma jet irradiation of a 2,2,5,5-tetramethyl-3-pyrroline-3-carboxam...
The direct decomposition of toluene-containing humidified air at large flow rates was studied in two types of reactors with dielectric barrier discharge (DBD) features in ambient conditions. A scalable large-flow DBD reactor (single-layer reactor) was designed to verify the feasibility of large-flow plasma generation and evaluate its decomposition...
We have developed a supersonic pulsed plasma jet device capable of long-distance and high-speed processing, and investigated its basic characteristics for surface treatment applications, mainly in the material and medical fields. The developed apparatus is equipped with a mechanism to transport active species in the plasma to the object to be treat...
The strawberry fruit contains abundant polyphenols, such as anthocyanins, flavan-3-ol, and ellagitannin. Polyphenol enrichment improves the quality of strawberries and leads to a better understanding of the polyphenol induction process. We measured the total polyphenol content of strawberry fruits under different growth conditions, developmental st...
Previously, we developed a method that uses temperature-controlled atmospheric-pressure plasma to induce protein uptake in plant cells. In the present work, we examined the mechanism underlying such uptake of a fluorescent-tagged protein in tobacco leaf cells. Intact leaf tissue was irradiated with N2 plasma generated by a multi-gas plasma jet and...
Atmospheric low-temperature plasma has received attention for application in disinfection methods. In this study, we develop a plasma bubbling method as a disinfection method. In the plasma bubbling method, the bactericidal effect can be introduced into the water by bubbling with carbon dioxide plasma. The plasma bubbling method is effective for th...
The purpose of this study was to investigate the effect of gas species used for low-temperature atmospheric pressure plasma surface treatment, using various gas species and different treatment times, on zirconia surface state and the bond strength between zirconia and dental resin cement. Three groups of zirconia specimens with different surface tr...
The intrinsic hydrophobicity of graphite felt (GF) is typically altered for the purpose of the surface wettability and providing active sites for the enhancement of electrochemical performance. In this work, commercial GF is used as the electrodes. The GF electrode with a coated-polydopamine catalyst is achieved to enhance the electrocatalytic acti...
In recent years, hydrogen has attracted remarkable attention as an energy vector which will help to reduce the emissions of CO2. According to the international standard (ISO 14687-2), the maximum concentration of sulfur in hydrogen used for fuel-cell vehicles should be lower than 0.004 ppm. In addition, the conventional method, such as gas chromato...
High-efficiency decomposition technology for volatile chemical warfare agent sarin was developed using a dielectric-barrier discharge (DBD). The power consumptions of the developed device for which the gap lengths of the plasma-generation sites were 1.0–2.0 mm, were found to be 22–27 W, respectively. The DBD driven sarin-decomposition amount per un...
Tailoring surface hydrophilicity on polyethylene terephthalate (PET) by a radio frequency (RF) atmospheric pressure plasma jet (APPJ) for grafting biomaterials was investigated in this study. Two thermally responsive biomaterials of hydrophilic non-ionic surfactant of polyoxyethylene polymer and hydroxypropyl cellulose were used, while hydroxyethyl...
Liquid electrode plasma (LEP) is used as an excitation source for compact and sensitive elemental analysis, where the channel damage by plasma causes the severe tradeoff between sensitivity and lifetime. In alternative current (AC)-LEP, significantly less channel damage (1/3000) was reported compared to direct current LEP (DC-LEP). However, the mec...
In this study, the relationship between plasma gas temperature and the bactericidal effects on five of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus (spore)) in liquid was investigated using a temperature-controllable plasma source. We determined that the bactericidal ability im...
The liquid electrode plasma (LEP) driven by alternating current (AC), which is used as an excitation source for elemental analysis, has been investigated in this work. In AC-LEP, microchannel showed remained gas bubble and small channel damage with same signal intensity compare to direct current LEP (DC-LEP) in previous work. However, the mechanism...
Currently, atmospheric plasmas are applied to the desorption and ionization of surface adhesive materials for rapid and highly sensitive analysis. One widely used chemical ionization method applies protons generated from atmospheric water molecules to a desorbed sample; however, detailed study of the ionization mechanism has not been addressed thus...
Fiber reinforced polypropylene(FRPP) has advantages of low cost and light weight. However, because of its low surface energy, bonding strength of FRPP is generally very low. Surface treatment before bonding is one of the candidates to solve this problem. In this study, the adherend was subjected to plasma treatment to improve the bonding strength o...
We developed a dual plasma desorption/ionization system using two plasmas for the semi-invasive analysis of compounds on heat-sensitive substrates such as skin. The first plasma was used for the desorption of the surface compounds, whereas the second was used for the ionization of the desorbed compounds. Using the two plasmas, each process can be o...
Background:
Nonthermal atmospheric pressure plasma (NTAPP) has recently received attention as a novel tool in medicine. It is thought that plasma components yield plasma effects such as sterilization, blood coagulation, and wound healing. These effects are produced without thermal damage. We investigated the blood coagulation effect of NTAPP by us...
To achieve a highly sensitive and onsite analysis of a small amount samples, a microplasma-based micro total analysis systems (μ-TAS) device was developed. A dielectric barrier discharge (DBD) that can generate a stable plasma at atmospheric pressure was generated in a microchip and used as the plasma source. The use of DBD suppresses the temperatu...
Primers and single-strand DNA sequences used in this study.
(XLSX)
To identify mechanisms underlying the bacterial inactivation process by atmospheric nonthermal plasma using a unique plasma jet that can generate various gas plasmas, Staphylococcus aureus were irradiated with carbon dioxide plasma, which produces a large amount of singlet oxygens, and nitrogen plasma, which produces a large amount of OH radicals....
Introducing analytic samples into plasma leads to the generation of light and ions. By detecting these ions and light, trace quantities of elements within the samples can be analyzed. The light and ions are generated not only by the high temperature of the plasma but also as a result of the complex atomic/molecular process within plasma. By underst...
The purpose of this study is to evaluate the sterilization effects of a newly developed low temperature multi gas plasma jet on oral pathogenic microorganisms (Streptococcus mutans [S. mutans], Lactobacillus fermentum [L. fermentum], Aggregatibacter actinomycetemcomitans [A. actinomycetemcomitans]). Plasma gas which generated from O2, N2, Ar and 50...
A novel liquid electrode plasma (LEP) driven by AC, which is used as an excitation source for elemental analysis, has been developed for the first time. The conditions such as chip layout and flow rate were found to produce the plasma in the channel. The mechanism of AC LEP generation was determined. AC LEP could be sustained in the resin channel w...
Liquid electrode plasma (LEP) is an excitation source for elemental analysis. The plasma is generated by electrical discharge at the narrower portion of a liquid channel when applying a high voltage to two electrodes inserted to the two ends of the liquid channel. Conventionally LEP is generated by direct current. More recently, we found the best c...
In this study, a small-sized plasma jet source with a 3.7 mm head diameter was created via a 3D printer. The jet’s emission properties and OH radical concentrations (generated by argon, helium, and nitrogen plasmas) were investigated using optical emission spectrometry (OES) and electron spin resonance
(ESR). As such, for OES, each individual gas p...
Various gas atmospheric nonthermal plasmas were generated using a multigas plasma jet to treat microbial suspensions. Results indicated that carbon dioxide and nitrogen plasma had high sterilization effects. Carbon dioxide plasma, which generated the greatest amount of singlet oxygen than other gas plasmas, killed general bacteria and some fungi. O...
A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by n...
A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by n...
We have developed a sample introduction system using a magnetic valve type dispenser, named “droplet direct injection nebulizer (D-DIN)”. In the case of D-DIN, sample solutions are directly injected as a single droplet or series of droplets into the plasma. Droplet volume can be controlled across a wide range of droplet size from 700 pL (110 µm) to...
Our group succeeded in developing a multi-gas plasma jet, which can generate plasma from various gas species. Using this plasma source, reactive species can be investigated in detail, since they can be generated selectively by the supplied gas species. This study aims to investigate the amount of reactive species generated by various gas plasmas, f...
Recently, various sterilization methods using atmospheric non-thermal plasma have been studied. Plasma generates reactive species that contributes to the sterilization. Most of the previous studies were reported that water treated by plasma irradiation (plasma treated water) shows sterilization ability. In these experiments, plasma is irradiated to...
An atmospheric pressure plasma source in which the gas temperature can be accurately controlled from below freezing point up to a high temperature has been developed. In general plasma devices, an electrical discharge is passed through a gas at about room temperature to generate plasma, so the plasma is at a temperature higher than room temperature...
An optimal signal acquisition and processing method for use with intermittent small-sized sample introduction techniques, such as the micro-droplet injection system (M-DIS), was investigated. This type of system is expected to play an important role in environmental and medical fields by enabling analysis of single cells or nanoparticles. A model s...
With a view to enhance the sensitivity of analytical instruments used in the measurement of trace elements contained in a single cell, we have now equipped the previously reported micro-droplet injection system (M-DIS) with a desolvation system. This modified M-DIS was coupled to inductively coupled plasma atomic emission spectroscopy (ICP-AES) and...
Regenerative medicine and environmental science require the analysis of ultrasmall samples such as cells and nanoparticles. Therefore, a microplasma atomic emission spectroscopy (AES) system was developed in this study. This system combined microdroplet injection, which can introduce a small droplet of a few tens of picoliters into a plasma excitat...
Plasma-based ambient desorption/ionization mass spectrometry (ADI–MS) has attracted considerable attention in many fields because of its capacity for direct sample analyses. In this study, a high-power pulsed microplasma jet (HPPMJ) was developed and investigated as a new plasma desorption/ionization source. In an HPPMJ, a microhollow cathode disch...
In this study, non-thermal multi-gas plasma treatments were performed for Tetrodotoxin (TTX) solution, and TTX decomposition was analyzed by liquid chromatography coupled with electrospray time-of-flight mass spectrometry. The TTX mass spectrum signal was reduced by plasma irradiations to different levels by using various gas species. Nitrogen plas...
Various plasma sources were used as ionization sources for ambient desorption/ionization mass spectrometry (ADI-MS) in the past. In the present study, a plasma jet, termed an atmospheric-pressure damage-free multi-gas plasma jet, which can generate a stable atmospheric low-temperature plasma with various gas species, was investigated and used as an...
A new inductively coupled plasma (ICP) torch with an air-cooling system has been designed and developed for both argon and helium plasma. The same torch and impedance-matching network could be used to generate stable Ar- and He-ICP. The torch consists of three concentric quartz tubes. The carrier gas, plasma gas, and cooling gas flow through the in...
To decrease the amount of sample solution in ICP-AES/MS, we developed a new droplet direct injection nebulizer (D-DIN) system in which aqueous solutions were not nebulized, but injected into the plasma as a series of small droplets. The typical droplet volume is 700 pL, which that is about 100-times larger than the droplets in the mist from usual c...
For stable plasma generation under introducing large-size sample droplets to ICP, we designed and developed free-running ICP. In the system, the impedance shift of the plasma generated by introducing the droplet is immediately cancelled by a shift of the RF resonant frequency of the entire system. To evaluate the shift of the frequency caused by ch...
It has been reported that planula larvae of some jellyfish prefer artificial substrates for settlement. This research focused on the relationship between the settlement of planulae and the wettability of artificial substrate surfaces. We used atmospheric plasmas to change the wettability of the surfaces of polycarbonate (PC) plates because plasma t...
In analytical chemistry, gas chromatography (GC) has been widely used because of the short measurement time and the low running costs. High-sensitivity detection is required for further improvement of the analytical performance. To date, several types of detectors have been developed. Thermal conductivity detectors (TCDs) are the most common GC det...
Conventional atmospheric plasma sources have some limitations in useable plasma gas species, and so biological effect did not be confirmed with various gas plasmas. To gener-ate various gas plasmas we have developed damage-free multi-gas plasma jet source. It can generate stable plasma with various gas species and the plasma does not give thermal d...
To achieve a highly sensitive and prompt elemental analysis of materials on heat-sensitive substrates, like living tissues, the atmospheric plasma soft-ablation method (APSA) was developed. The damage-free plasma, which has room temperature and no risk of electrical shock, was used as a sampling medium for materials, and the sampled materials were...
We developed an injection gas heating system for introducing large droplets, because we want to effectively to measure elements in a single cell. This system was applied to ICP-atomic emission spectrometry (ICP-AES), to evaluate it performance. To evaluate the effect of the emission intensity, the emission intensity of Ca(II) increased to a maximum...
The development and use of a single-fluid two-temperature approximated
2-D Magneto-Hydrodynamics code is reported. Z-pinch dynamics and the
evolution of Magneto-Rayleigh-Taylor (MRT) instabilities in a gas jet
type Extreme Ultraviolet (EUV) source are investigated with this code.
The implosion and stagnation processes of the Z-pinch dynamics and th...
In recent years, atmospheric plasma sources have been developed for industrial applications, because of its no need of vacuum pumping system or chambers and high-density plasma can be generated. However, conventional atmospheric plasma sources have a limitation of usable plasma gas species and a problem of thermal or electric discharge damage to ta...