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When a tissue slice pretreated with gold nanoparticles is irradiated with a focused 532-nm continuous wave laser, desorption is observed to be uniform and stable, and its shape is sharp and steep. However, since the desorbed molecules are still electrically neutral particles in atmospheric pressure (AP), additional procedure of ionizing them is necessary for AP mass spectrometry (AP-MS) analysis. Therefore, the authors have combined an electrospray device with a simple chamber connected to the airflow-assisted particle transport equipment mounted at the mass spectrometer inlet. Subsequent ionization processes using an electrospray device enable the detection of several types of diacylglycerol molecules above 500 Da, which cannot be detected with the use of AP plasma jets. The authors also developed a remote AP-MS using a long and flexible sampling probe and a fiber laser with a slight modification of the proposed AP desorption and ionization method.

We report a high spatial resolution mass spectrometry (MS) system that allows us to image live hippocampal tissue slices under open-air atmospheric pressure (AP) and ambient temperature conditions at the subcellular level. The method is based on an efficient desorption process by femtosecond (fs) laser assisted with nanoparticles and a subsequent ionization step by applying nonthermal plasma, termed AP nanoparticle and plasma assisted laser desorption ionization (AP-nanoPALDI) MS method. Combining the AP-nanoPALDI with microscopic sample scanning, MS imaging with spatial resolution of 2.9 µm was obtained. The observed AP-nanoPALDI MS imaging clearly revealed the differences of molecular composition between the apical and basal dendrite regions of a hippocampal tissue. In addition, the AP-nanoPALDI MS imaging showed the decrease of cholesterol in hippocampus by treating with methyl β-cyclodextrin, which exemplifies the potential of AP-nanoPALDI for live tissue imaging for various biomedical applications without any chemical pretreatment and/or labeling process.

In this study, we describe an atmospheric pressure plasma jet (APPJ) device made of four-bore tubing operable in inhospitable humid environments and introduce two potential applications of liquid material processing: decomposition of aqueous phosphorus compounds and solution-plasma polymerization. A four-bore tube was used as the plasma transfer conduit and two diagonal bores contained metal wires. In the proposed APPJ device, the metal wires serving as electrodes are completely enclosed inside the holes of the multi-bore glass tube. This feature allows the APPJ device to operate both safely and reliably in humid environments or even underwater. Thus, we demonstrate that the proposed electrode-embedded APPJ device can effectively decompose aqueous phosphorus compounds into their phosphate form by directly processing the solution sample. As another application of the proposed APPJ device, we also present the successful synthesis of polypyrrole nanoparticles by solution plasma polymerization in liquid pyrrole. [ABSTRACT FROM AUTHOR]

We review recently developed methods for analyzing live cells and tissues in ambient conditions without the use of harsh chemical fixation or physical freezing and drying. The first method is based on laser ablation in atmospheric pressure assisted by atmospheric pressure plasma and nanomaterials such as nanoparticles and graphene to enhance laser ablation. The second method is based on secondary ion mass spectrometry imaging of live cells in solution capped with single‐layer graphene to preserve intact and hydrated biological samples even under ultrahigh vacuum for secondary ion mass spectrometry bio‐imaging in solution with subcellular spatial resolution. Mass spectrometry imaging of small molecules from live cells and tissues can provide an innovative molecular imaging methodology for several biomedical and material research applications. [ABSTRACT FROM AUTHOR]

This paper investigated the chemical bonding features and conductivity characteristics of atmospheric pressure plasma (APP) conducting polymerized polypyrrole (pPPy) by iodine (I2) doping method in coupling and remote conditions, respectively. The I2 doped APP pPPy film surfaces were analyzed by field-emission scanning electron microscopy (FE-SEM). Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analyses were used to determine the crystallinity and chemical bond of I2 doped APP pPPy film for both coupling and remote conditions, respectively. In terms of crystallinity and bonding structure, I2 doped APP pPPy film, which was obtained by coupling condition, had own advantages, such as existence of abundant multiple bond (C≡C/C≡N) with π-electron, improved crystallinity, and lower initial resistance compared to that of remote condition. Whereas, the dense and thick I2 doped APP pPPy film obtained by remote condition was less hydrated and shown lower resistivity change-rate under ambient air compared to that of coupling condition. Therefore, different resistivity and humidity characteristics of I2 doped APP pPPy films depending on growth condition such as remote and coupling conditions contribute to increasing the possibility of using the I2 doped APP pPPy film as flexible electrode-materials. [ABSTRACT FROM AUTHOR]

This work presents a deposition of carbon thin films on the substrate from sucrose-containing-carbon source, that is, sugar, by using the two different plasma processes; one process is that the carbon particles are obtained from the sugar in the stable solution plasma reactor with external resistor, and the other process is that the carbon thin films are deposited on the substrate from the carbon particles obtained from sugar by using the atmospheric pressure plasma (APP) spray method. The carbon particles are obtained at a bipolar pulse waveform with a peak value of 1.5 kV and a frequency of 5 kHz under solution plasma, whereas the carbon thin films are deposited at a sinusoidal pulse waveform with a peak value of 12.5 kV and a frequency of 33 kHz under the APP spray method. Voltage probe, discharge current, and optical emission spectrometer (OES) techniques are used to analyze the plasma produced from the solution plasma reactor. Field emission scanning electron microscopy (FE-SEM) and ultraviolet-visible (UV-vis) spectroscopy techniques are used to analyze the carbon particles. FE-SEM results show that carbon materials from sucrose have a few ten to hundred nanometer size nanoparticles characteristics. The UV-vis and OES analyses show the characteristic graphene peaks with evidence that carbon sources from sucrose are broken due to discharge energy. This study contributes to a better understanding on the new synthesis method of carbon materials from renewable resource with low-cost, i.e. sugar cane. [ABSTRACT FROM AUTHOR]

This article has analyzed conducting polymer from the viewpoint of material properties, which is polymerized under atmospheric pressure condition for coupling and remote conditions, respectively. The experimental results show that the atmospheric pressure plasma polymerized pyrrole (pPPy) exhibits similar characteristics from the viewpoint of crystallinity, but the shapes and roughness of the particles are significantly distinguished. In the case of coupling condition, a uniform and flat layer like a thin film was obtained. However, in the case of remote condition, the deposited layer had more rough nanoparticles compared to that of coupling condition. The pPPy surface characteristic and morphology changes are discussed by using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) results. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis are used to determine the chemical changes introduced by the atmospheric pressure plasma for coupling and remote conditions. The both pPPy materials, which were obtained by coupling and remote conditions, are expected to be applied to various fields, especially for designing the thin conducting electrode layer of polymer light emitting diode (P-LED) or for improving the efficiency by inserting conducting polymer powder on hole injection layer. [ABSTRACT FROM AUTHOR]

In atmospheric pressure (AP) plasma polymerization, increasing the effective volume of the plasma medium by expanding the plasma-generating region within the plasma reactor is considered a simple method to create regular and uniform polymer films. Here, we propose a newly designed AP plasma reactor with a cruciform wire electrode that can expand the discharge volume. Based on the plasma vessel configuration, which consists of a wide tube and a substrate stand, two tungsten wires crossed at 90 degrees are used as a common powered electrode in consideration of two-dimensional spatial expansion. In the wire electrode, which is partially covered by a glass capillary, discharge occurs at the boundary where the capillary terminates, so that the discharge region is divided into fourths along the cruciform electrode and the discharge volume can successfully expand. It is confirmed that although a discharge imbalance in the four regions of the AP plasma reactor can adversely affect the uniformity of the polymerized, nanostructured polymer film, rotating the substrate using a turntable can significantly improve the film uniformity. With this AP plasma reactor, nanostructured polythiophene (PTh) films are synthesized and the morphology and chemical properties of the PTh nanostructure, as well as the PTh-film uniformity and electrical properties, are investigated in detail. [ABSTRACT FROM AUTHOR]

The morphological and chemical properties of polyaniline (PANI) nanocomposite films after adding small amounts of auxiliary gases such as argon, nitrogen, and oxygen during atmospheric pressure (AP) plasma polymerization are investigated in detail. A separate gas-supply line for applying an auxiliary gas is added to the AP plasma polymerization system to avoid plasma instability due to the addition of auxiliary gas during polymerization. A small amount of neutral gas species in the plasma medium can reduce the reactivity of monomers hyperactivated by high plasma energy and prevent excessive crosslinking, thereby obtaining a uniform and regular PANI nanocomposite film. The addition of small amounts of argon or nitrogen during polymerization significantly improves the uniformity and regularity of PANI nanocomposite films, whereas the addition of oxygen weakens them. In particular, the PANI film synthesized by adding a small amount of nitrogen has the best initial electrical resistance and resistance changing behavior with time after the ex situ iodine (I2)-doping process compared with other auxiliary gases. In addition, it is experimentally demonstrated that the electrical conductivity of the ex situ I2-doped PANI film can be preserved for a long time by isolating it from the atmosphere. [ABSTRACT FROM AUTHOR]

New nanostructured conducting porous polythiophene (PTh) films are directly deposited on substrates at room temperature (RT) by novel atmospheric pressure plasma jets (APPJs) polymerization technique. The proposed plasma polymerization synthesis technique can grow the PTh films with a very fast deposition rate of about 7.0 μm·min−1 by improving the sufficient nucleation and fragment of the thiophene monomer. This study also compares pure and iodine (I2)-doped PTh films to demonstrate the effects of I2 doping. To check the feasibility as a sensing material, NO2-sensing properties of the I2-doped PTh films-based gas sensors are also investigated. As a result, the proposed APPJs device can produce the high density, porous and ultra-fast polymer films, and polymers-based gas sensors have high sensitivity to NO2 at RT. Our approach enabled a series of processes from synthesis of sensing materials to fabrication of gas sensors to be carried out simultaneously. [ABSTRACT FROM AUTHOR]

The use of low-voltage-driven plasma in atmospheric pressure (AP) plasma polymerization is considered as a simple approach to reducing the reactivity of the monomer fragments in order to prevent excessive cross-linking, which would have a negative effect on the structural properties of the polymerized thin films. In this study, AP-plasma polymerization can be processed at low voltage by an AP-plasma reactor with a wire electrode configuration. A bare tungsten wire is used as a powered electrode to initiate discharge in the plasma area (defined as the area between the wide glass tube and the substrate stand), thus allowing plasma polymerization to proceed at a lower voltage compared to other AP-plasma reactors with dielectric barriers. Thus, transparent polyaniline (PANI) films are successfully synthesized. The surface morphology, roughness, and film thickness of the PANI films are characterized by field emission scanning electron microscopy and atomic force microscopy. Thus, the surface of the polymerized film is shown to be homogenous, smooth, and flat, with a low surface roughness of 1 nm. In addition, the structure and chemical properties of the PANI films are investigated by Fourier transform infrared spectroscopy, thus revealing an improvement in the degree of polymerization, even though the process was performed at low voltage. [ABSTRACT FROM AUTHOR]

A newly designed atmospheric pressure plasma jet that can generate plasma without an external power line for use in an inhospitable humid environment is proposed. A four-bore tube is employed as the delivery conduit, and wire electrodes are inserted into two diagonal hollows. As the wire electrodes are completely isolated inside the hollows of the multibore glass tube, there is no contact with the environment at the end of the device where the jet is produced. Two identical plasma plumes can be generated not only in the ambient air but also under water, thereby enabling tissue and wound treatments in a humid environment, such as oral medicine and endodontic care. [ABSTRACT FROM PUBLISHER]

The plasma jet-to-jet coupling behavior between two plasma jet arrays is investigated. A plasma array structure consisting of two plasma jet arrays and a double electrode configuration is used as an ambient plasma source and shown to generate a strong plasma emission. Since the proposed plasma device is able to generate an intense plasma emission without any external ground electrode, it is a promising tool for surface treatments and modifications that require a strong discharge process, regardless of the dielectric property of the target material. [ABSTRACT FROM PUBLISHER]

A new plasma array jet with an additional ring-type focusing electrode is proposed to obtain an extended and intense Ar plasma jet focused on a central glass tube at atmospheric pressure. To investigate the role of the ring-type electrode, the sinusoidal voltages of 9 kV and frequency of 30 kHz were applied to three different electrode configurations, such as only ring-type electrode, only probe-type electrodes, and both the ring- and probe-type electrodes. As a result, the ring-type electrode is confirmed to play a significant role in spatially focusing the charge particles ignited by the exposed probe-type electrodes, thereby producing a stable and intense Ar plasma jet under atmospheric pressure. [ABSTRACT FROM PUBLISHER]

The authors describe an intense plasma plume from atmospheric-pressure plasma jet array devices. Here, outer plasma plumes, produced by this device, were sucked into the centered plasma plume at the ends of the tubes and merged with the centered plume. The intense plasma jet is possible through jet-to-jet coupling in eight-quartz-tube arrays. To describe this coupling, optical properties of the intense plasma jet are compared with those of a single tubing plasma jet. The optical intensity from the intense plasma jet by jet-to-jet coupling was approximately three times larger than that of a conventional single plasma jet under identical driving and gas conditions. [ABSTRACT FROM AUTHOR]

ZnO nanowire arrays on polyethylene terephthalate substrate were characterized, in terms of surface energy, by the honeycomb structured plasma jets for biosensors. A rapid hydrothermal synthesis is carried out to grow ZnO nanowires by a variable power microwave sintering system. The optical emission spectra of the honeycomb structured plasma jet array show that excited OH, \N2, \N2^{+}, He, and O exist in the plasma jet array and the many gaseous species in the air participated in the plasma process. Surface modification by atmospheric plasma resulted in reduced contact angles from 111.23^\circ to 8.70 ^\circ as a function of plasma duration time. [ABSTRACT FROM AUTHOR]

A dual atmospheric-pressure plasma jet using a theta-shaped tube has been proposed for generating the plasma jet with multigases. Two individual plasma plumes of He and Ar were generated and focused at a certain point. When the gas flow ratio was 3:1 between the Ar and He gases, the dual plasma plume exhibited the longest focal distance from the nozzle, and it was sustaining as a well-balanced state. The optical emission spectra of the plasma plume showed that the merged plasma plume had both excited He and Ar species. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure microplasma jets from a linear array of five hollow-core optical fibers are described. All plasma plumes from the array were quite narrow but long enough to apply the direct treatments to a very small object. The optical intensities from five individual plasma jets were also stable and had a good uniformity. The variation of the optical intensities of individual plasma plumes was within 15%. This plurality of the small-sized plasma jets can be utilized to target some groups of different cells simultaneously in an in vitro biomedical application. [ABSTRACT FROM AUTHOR]

A flexible atmospheric pressure microplasma jet device utilizing a 200-\mu \m hollow-core optical fiber was developed in order to trigger the apoptosis of cultured tumor cells and determine the feasibility of plasma endoscopy. As determined by in situ apoptosis assay, the TUNEL assay, this flexible microplasma jet induced cultured murine tumor cells to undergo apoptosis. In addition, the apoptosis was induced to a greater extent in B16F0 tumor cells than in CL.7 cells for the same plasma dose. [ABSTRACT FROM AUTHOR]

The authors describe an intensified plasma jet from a honeycomb structural plasma jet array at atmospheric pressure. Despite an equally distributed gas flow, the outermost tubes did not produce strong individual plumes. Rather, the plasma plumes were drawn into the central plume, which was, in turn, amplified. As a result, the optical intensity from the 19-array plasma jet was nearly twice greater than that from a conventional single plasma jet at the maximum plasma emission condition of each device under identical applied voltages. [ABSTRACT FROM AUTHOR]

Reported here is the low-temperature growth of multiple-stack high-density ZnO nanoflower/nanorod structures on polyethylene naphthalate (PEN) substrates derived from the surface modification of ZnO seed layers using an atmospheric-pressure plasma jet (APPJ) treatment. The plasma treatment could provide several advantages to the growth of multiple-stack ZnO nanoflower/nanorod structures: (i) the surface wettability of the seed layers changes from hydrophobic to hydrophilic, resulting in higher surface energies for the growth of high-density ZnO nanoflowers, (ii) the nucleation sites increase due to the increased surface roughness caused by the plasma etching, and (iii) there is no thermal damage to the plastic substrate from the plasma treatment due to its low-temperature weakly ionized discharge. It was also confirmed that multiple stacks of ZnO nanoflowers were obtained without degradation of the crystal quality or modification to the crystal shape or phase. The ZnO nanoflower/nanorod structures grew by lengths up to 4 μm due to an increased surface roughness of 10% and surface energy 5.5 times that of the seed layers. As shown, the APPJ is a very good method to obtain high-density ZnO nanostructures on plastic substrates below 150 °C, as is critical for flexible electronics. [ABSTRACT FROM AUTHOR]