Non-thermal Atmospheric Plasma Research Articles

Novel Nonthermal Atmospheric Plasma Irradiation of Titanium Implants Promotes Osteogenic Effect in Osteoporotic Conditions.

Osteoporosis is a metabolic disease characterized by bone density and trabecular bone loss. Bone loss may affect dental implant osseointegration in patients with osteoporosis. To promote implant osseointegration in osteoporotic patients, we further used a nonthermal atmospheric plasma (NTAP) treatment device previously developed by our research group. After the titanium implant (Ti) is placed into the device, the working gas flow and the electrode switches are turned on, and the treatment is completed in 30 s. Previous studies showed that this NTAP device can remove carbon contamination from the implant surface, increase the hydroxyl groups, and improve its wettability to promote osseointegration in normal conditions. In this study, we demonstrated the tremendous osteogenic enhancement effect of NTAP-Ti in osteoporotic conditions in rats for the first time. Compared to Ti, the proliferative potential of osteoporotic bone marrow mesenchymal stem cells on NTAP-Ti increased by 180% at 1 day (P = 0.004), while their osteogenic differentiation increased by 149% at 14 days (P < 0.001). In addition, the results indicated that NTAP-Ti significantly improved osseointegration in osteoporotic rats in vivo. Compared to the Ti, the bone volume fraction (BV/TV) and trabecular number (Tb.N) values of NTAP-Ti in osteoporotic rats, respectively, increased by 18% (P < 0.001) and 25% (P = 0.007) at 6 weeks and the trabecular separation (Tb.Sp) value decreased by 26% (P = 0.02) at 6 weeks. In conclusion, this study proved a novel NTAP irradiation titanium implant that can significantly promote osseointegration in osteoporotic conditions.

Effects of solution chemistry on dielectric barrier atmospheric non-thermal plasma for operative degradation of antiretroviral drug nevirapine

The global prevalence of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) has been an environmental menace. Tons of drug wastes from antiretroviral therapy are released into the environment annually. We, for the first time, employed the novel dielectric barrier atmospheric non-thermal plasma (DBANP) discharge, to mitigate the inadvertent pollution arising from the antiretroviral therapy. A 40-min treatment of nevirapine achieved >94 % (0.075 min−1) removal efficiency at discharge power of 63.5 W and plasma working gas of atmospheric air. Chemical probes confirmed •OH, ONOO− and eaq− as the dominant reactive species whilst further revealing the reaction acceleration role of NaNO3 and CCl4 which are known reaction terminators. The commonly coexisting inorganic anions potentiated nevirapine removal with over 98 % efficiency, achieving the highest rate constant of 0.148 min−1 in this study. Moreover, the initial solution pH (1.5–11.1) was no limiting factor either. The insensitivity of the DBANP discharge to actual water matrices was an eminent inference of its potential applicability in practical conditions. With reference to data obtained from the liquid chromatography-mass spectrometer analysis, nevirapine degradation pathway was proposed. A nucleophilic attack by ONOO− at the cyclopropyl group and •OH attack at the carbonyl carbon of the amide group, respectively, initiated nevirapine degradation process. It is anticipated that the findings herein, will provide new insights into antiretroviral drug waste management in environmental waters using the innovative and green non-thermal plasma process.

Atmospheric non-thermal plasma inactivation of Ascosphaera apis, the causative agent of chalkbrood disease in honeybee

Ascosphaera apis is a worldwide pathogenic fungi of honeybees that can cause a decline in bee populations. In this study, we investigated the antifungal activity of non-thermal plasma on fungal growth. Spore inactivation after exposure to gas plasma by liquid phase and plasma activated water (PAW) and pathogenicity of A. apis in vivo were also examined. The results demonstrated that the mycelial growth of fungi was completely inhibited after argon plasma treatment. Both gas plasma and PAW exposures resulted in a significant decrease of A. apis spore numbers, maximum reduction of 1.71 and 3.18-fold, respectively. Germinated fungal spores on potato dextrose agar were also reduced after plasma treatment. SEM analysis revealed a disruption in the morphological structure of the fungal spores. The pathogenicity of A. apis on honeybee larvae was decreased after spores treated by gas plasma and PAW with a disease inhibition of 63.61 ± 7.28% and 58.27 ± 5.87%, respectively after 7 days of cultivation. Chalkbrood in honey bees have limited control options and our findings are encouraging. Here, we demonstrate a possible alternative control method using non-thermal plasma for chalkbrood disease in honeybees.

Study on the Degradation Mechanism of Pollutants Using Nonthermal Atmospheric Plasma Synergized Supported by Catalyst

Study on the Degradation Mechanism of Pollutants Using Nonthermal Atmospheric Plasma Synergized Supported by Catalyst

Potential Uses of Nonthermal Atmospheric Pressure Technology for Dermatologic Conditions in Children.

Nonthermal atmospheric plasma (NTAP)(also known as cold atmospheric plasma [CAP]) is a rapidly emerging technology showing promising treatment results for a wide variety of dermatologic conditions. Research on NTAP for the treatment of pediatric dermatologic conditions is limited. We conducted a systematic review to elucidate reported applications of NTAP for skin conditions in children. Overall, NTAP offers a promising safety profile and painless treatment option that has the potential to deliver similar efficacy to many standard therapies in pediatric dermatology.

On the Effect of Non-Thermal Atmospheric Pressure Plasma Treatment on the Properties of PET Film.

The aim of the work was to investigate the effect of non-thermal plasma treatment of an ultra-thin polyethylene terephthalate (PET) film on changes in its physicochemical properties and biodegradability. Plasma treatment using a dielectric barrier discharge plasma reactor was carried out in air at room temperature and atmospheric pressure twice for 5 and 15 min, respectively. It has been shown that pre-treatment of the PET surface with non-thermal atmospheric plasma leads to changes in the physicochemical properties of this polymer. After plasma modification, the films showed a more developed surface compared to the control samples, which may be related to the surface etching and oxidation processes. After a 5-min plasma exposure, PET films were characterized by the highest wettability, i.e., the contact angle decreased by more than twice compared to the untreated samples. The differential scanning calorimetry analysis revealed the influence of plasma pretreatment on crystallinity content and the melt crystallization behavior of PET after soil degradation. The main novelty of the work is the fact that the combined action of two factors (i.e., physical and biological) led to a reduction in the content of the crystalline phase in the tested polymeric material.

Understanding the mechanisms of action of atmospheric cold plasma towards the mitigation of the stress induced in molds: The case of Aspergillus chevalieri

Aspergillus chevalieri is a xerophilic/xerotolerant fungi affecting dried food products. In this study the ability of non-thermal cold atmospheric plasma (CAP) at high power density (NOx) to affect biological process inducing the stress responses of A. chevalieri species exposed for 5 min (5’CAP-NOx) and 30 min (30’CAP-NOx) were analysed at 0, 1, 6, 12 and 48-h post treatment (hpt). At 48 hpt with 30’CAP-NOx, 84% of fungal growth reduction was observed. The membrane integrity estimated by confocal investigation after carboxyfluorescein diacetate/propidium iodide staining showed the dead surface mycelium layers exposed to the treatments. Reverse transcription-quantitative real-time PCR revealed an early downregulation, at 0 hpt, followed by upregulation or recovery starting to 1 hpt, of selected key genes involved in fungal stress responses. The cellular response to stress was confirmed by mycelial glutathione accumulation in the early phase after both CAP-NOx treatments, at 0 and 1 hpt, followed by the strong glutathione reduction at 12 and 48 hpt using 30’CAP-NOx treatment. The ability of A. chevalieri to modulate metabolic profile according to treatments was underlined by volatilome investigation, which mainly involved lipid metabolism. This work highlighted the adaptative response mechanisms of A. chevalieri to overcome the CAP-NOx treatment. Industrial relevanceThe application of cold atmospheric plasma (CAP) technology to avoid microbial growth in foods is considered of high interest. Utilization of CAP technology, a nonthermal technique, is encouraged because of its efficiency in maintaining natural aroma and flavor and product shelf-life. Regarding the management of Aspergillus chevalieri, the developments in mechanistic insights indicated that cold plasma affected several targets in fungal cells and was a successful tactic when employed to stop the selection of resistant fungal strains.

A novel combination of non-thermal plasma process and a heterogenous nanophotocatalyst-sorbent comprising zinc sulfide, graphene oxide and polyaniline as an efficient strategy for treatment of organic-contaminated water

A dielectric barrier discharge (DBD) reactor was designed in the present study to generate non-thermal atmospheric pressure Ar plasma. A heterogeneous p-n-p visible-driven photocatalyst comprising ZnS, Graphene oxide, and Polyaniline (ZGP) was also synthesized via chemical polymerization. A novel combination of photocatalyst and plasma treatment was then developed for the synergetic removal of organic pollutants from aqueous solutions. The addition of the p-n-p photocatalyst (5 mg) to the dye solution (malachite green, 50 mL, 20 mg/L) under plasma radiation resulted in a 97 % removal rate in 12 min. Scavenging studies confirmed a decline in the effectiveness of the reactive species in the following order: OH• > e־ > O2־• > h+. The changes in surface chemistry of the recovered photocatalyst were probed by XPS, and possible involved reactions were suggested. The synergetic factor of 1.53 in this system was a remarkable achievement comparable with the records of air or oxygen plasma reactors. The absence of hazardous by-products was confirmed by GC–MS and AAS techniques. The treated aqueous solution was utilized to evaluate its effect on lentil seed growth and trout blood factors, which led to promising results with several advantages but no negative effects.

Production of restructured beef jerky using blood plasma solutions activated by non-thermal atmospheric plasma

Abstract The effect of blood plasma powder (2.5, 5, and 7.5% w/w in water) activated using non-thermal atmospheric plasma (T1, T2, and T3, respectively) was investigated as a nitrite source in the production of restructured beef jerky. A group without a nitrite source (NC) and a group cured with 100 ppm of sodium nitrite (PC) were used as negative control and positive control groups, respectively. The nitrite content of the plasma-activated solutions was adjusted to match that of the positive control by calculating the required plasma treatment time, based on previous studies. The obtained results showed that addition of treated solutions with nonthermal plasma for a 70 min, at a level of 20% in relation to the meat, can have beneficial effects on nitrosylhemochrome content, redness, and TBARS values of restructured jerky. These effects were statistically comparable (p≥0.05) to sodium nitrite-cured samples. Furthermore, compared to the PC group, the T1, T2, and T3 treatments exhibited significantly lower water activity and higher protein content (p&lt;0.05). The T2 and T3 treatments also showed increased lightness and shear force values (p&lt;0.05) compared to the control groups (NC and PC). It should be noted that the T3 group had the highest (p&lt;0.05) residual nitrite content among all the samples. However, a sensory analysis is necessary to assess consumer acceptance with regard to differences in the odor profile of the treatments, according to the Principal Components Analysis (PCA).

Inhibitory effects of non-thermal atmospheric plasma on Yersinia enterocolitica and Staphylococcus aureus in the Korean traditional non-fermented kimchi “Geotjeori”

Food-borne bacteria have frequently been detected in kimchi, a representative and traditional fermented ethnic food of Korea. This study investigated the effect of atmospheric dielectric barrier discharge (DBD) plasma treatment (1.1 kV, 43 kHz, N2: 1.5 m/s, 5–60 min) on reduction of Yersinia enterocolitica and Staphylococcus aureus and on quality parameters in Geotjeroi, a non-fermented kimchi. A decrease of 0.12/0.09, 0.19/0.19, 0.34/0.45, 0.64/0.72, and 1.13/1.12 log10 CFU/g was observed by 5, 10, 20, 30, and 60 min of DBD plasma, respectively. D-value of 52.83 and 51.95 min was determined for Y. enterocolitica (R2 = 0.99) and S. aureus (R2 = 0.98) using the first order kinetics model. The quality parameters (pH, Brix, and hardness) were not significantly different (P > 0.05) between treated and untreated Geotjeori. Moreover, a decrease of >1 log10 CFU/g, for both bacteria was observed without any change in the quality of Geotjeori. These findings imply that DBD plasma treatment enhances Geotjeori safety and protects product from microbial risk.

Effect of Humidity on the Inactivation of Bacillus Subtilis Spore by Non-thermal Atmospheric Air Plasma

Objective: If a medical device is not properly disinfected, it will pose a potential danger to patients. Spore is an experimental strain to verify the effect of disinfection on medical devices. It has a complex structure and is somewhat resistant to conventional disinfection techniques. Based on the advantages of simple structure and abundant reactive oxygen and nitrogen species (RONS), surface dielectric barrier discharge (SDBD) has been used to deal with inactivate spores, which provided experimental support for the application of sterilization spores in medical devices. Methods: The sterilization efficiency of the plasma was evaluated by calculating the number of viable colonies on Tryptose Soya Agar. RONS including ozone, nitrogen oxides and other reactive species produced in SDBD were measured by ozone analyzer, Fourier infrared spectrometer and chemical probes, respectively. Ultraviolet-visible spectrophotometer was used to determine the concentration of protein and nucleic acid. Results: After 20min of SDBD treatment, the number of inactivated spores could reach more than 4 log at high humidity (&gt;6g/m3), while the spores were hardly inactivated at low humidity (&lt;6g/m3). Ozone production was inhibited with increasing humidity while OH radicals and peroxynitrous acid increased with increasing humidity. The optical density values of protein and nucleic acid released from spores treated with SDBD was detected and a strong correlation was found with the spore inactivation trend. The protein shell and membrane structure of the spores were destroyed by SDBD, and more leakage and destruction of proteins and nucleic acids in the spores were obtained under the high humidity. Conclusion: With the increase of air humidity (from 0.15g/m3 to 70.16g/m3), stable SDBD is obtained showing a typical filamentous discharge pattern. Compared with low humidity, high humidity is more favorable to SDBD inactivation of spores.

Argon Plasma Treatment Effects on the Micro-Shear Bond Strength of Lithium Disilicate with Dental Resin Cements.

The low bond strength of lithium disilicate (LD) ceramics to dental resin cements remains a critical issue for dental applications because it leads to frequent replacement and causes tooth tissue destruction and consumption. The objective of this study was to examine the effects of atmospheric non-thermal argon plasma (NTP) treatment on LD to improve its micro-shear bond strength (μSBS) with dental resin cements because LD mostly experiences shear stress for its commonly used dental applications as crowns or veneers. Argon plasma treatment was performed on hydrofluoric (HF) acid-etched LD surfaces, and then commercial resin cements were subsequently applied to the treated LD surfaces. The plasma treatment significantly reduced the water contact angle of the LD surface to less than 10° without changing the surface morphology. The μSBS test was performed with cement-bonded LD samples after 24 h and 30 days, as well as after 1000 cycles of thermal cycling. The test results show that, as compared with the untreated controls, 300 s of plasma treatment significantly improved the LD-resin cement bond strength by 59.1%. After 30 days of storage in DI water and 1000 cycles of thermal cycling, the plasma-treated LD samples show 84.2% and 44.8% higher bond strengths as compared to the control samples, respectively. The plasma treatment effect on LD surfaces diminished rapidly as the bond strength decreased to 25.5 MPa after aging in the air for 1 day prior to primer and cement application, suggesting that primers should be applied to the LD surfaces immediately after the plasma treatment. These results demonstrate that, when applied with caution, plasma treatment can activate LD surfaces and significantly improve the SBS of LD with dental resin cements in both short-term and long-term periods.

Enhanced Adhesion of Copper Films on Fused Silica Glass Substrate by Plasma Pre-Treatment.

A non-thermal atmospheric jet plasma pre-treatment technique was introduced to help the growth of extremely sticky copper films on fused silica glass substrates. A tape test was utilized to assess the bonding quality between copper films and fused silica glass substrates. AFM was used to characterize the sample surface roughness and XPS for chemical bonding characterization. The Owens-Wendt method and a Theta Lite Optical Tensiometer were used to analyze the contact angle and surface energy. The results showed that the surface energy greatly increased from 34.6 ± 0.3 mJ·m-2 to 55.9 ± 0.4 mJ·m-2 after 25 s plasma pre-treatment due to the increasing Si-O and Si-N concentrations, which brought about the electrostatic force increasing at the copper/glass interface. After 25 s plasma pre-treatment, the average surface roughness (Sa) grew from 0.8 ± 0.1 nm to 2.4 ± 0.3 nm. With higher surface roughness, there were more spaces and vacancies for the copper atoms to make contact on the bonded surfaces and increase the mechanical bite force. The electrostatic force and the mechanical bite force on the interface helped to form an atomic diffusion connection layer and improved the interactions between the copper film and the glass substrate. The findings in the SEM supported the conclusions stated above. Therefore, the adhesion between copper films and fused silica glass substrates increased by about 20% by 25 s plasma pre-treatment compared with the untreated glass substrate.

Electrohydrodynamic devices for ionic wind generation and airborne positive‐strand RNA viruses inactivation by nonthermal atmospheric plasma

AbstractAdaptable technologies capable of reducing contaminants in enclosed spaces are needed. The SARS‐CoV‐2 pandemic has highlighted the vulnerability of current systems forcing the adoption of extreme measures, causing a significant socioeconomic impact. Electrohydrodynamic devices are proposed as a competitive solution that allows obtaining a high degree of viral inactivation with a very low generation of chemical compounds and low power consumption, together with the production of an airflow, which makes its implementation in real environments easy. In this study, airborne positive‐strand RNA viruses are treated with nonthermal atmospheric plasma, achieving &gt;3.4‐logR for HCoV‐229E and Bacteriophage‐MS2 and &gt;2.4‐log SARS‐CoV‐2 at 4W, in a single pass, at O3 and NO2 concentrations ≤0.70 ppm. Electrical, fluid‐dynamic, and chemical characterization provides the design rules.

Atmospheric Non-thermal Plasma Reduction of Natively Oxidized Iron Surfaces

Plasma in hydrogen-containing atmospheres is an efficient method for the reduction of iron oxides. Although a vast number of approaches were performed for the reduction of bulk Fe oxides with thermal hydrogen plasmas, there is almost no information about the non-thermal plasma reduction efficiency in the atmospheric pressure range. In the current article we present the reduction of natively oxidized iron surfaces applying a dielectric barrier discharge plasma in an Ar/H2 atmosphere at 1000 hPa. By varying the surface temperature from 25 to 300 °C, we studied the plasma reduction efficiency, which was then compared with a thermal method. Whereas plasma treatments at 25 °C and 100 °C did not result in the significant reduction of iron oxidized species, experiments at 200 °C and 300 °C yielded a reduction of approximately 88% and 91% of initial oxidized components already after 10 s, respectively. Moreover, we observed an increase in the efficiency with a plasma-thermal reduction in comparison to a thermal method, which was attributed to the presence of atomic hydrogen in the plasma phase. Analysis of morphology revealed the formation of Fe–C structures on surfaces after thermal and plasma-thermal treatments at 200 °C and 300 °C that may be connected with the diffusion of bulk contaminations to the deoxidized surface and reactions between the reduced Fe with plasma-activated adventitious carbon. Conclusively, the plasma was characterized by analyzing the reactive species and the electron temperatures.

Inactivation of Cercospora lactucae-sativa through Application of Non-Thermal Atmospheric Pressure Gliding Arc, Tesla Coil and Dielectric Barrier Discharge Plasmas

Cercospora leaf spot disease is a serious problem for lettuce cultivation worldwide. Cercospora lactucae-sativa, the causative agent of leaf spot disease on lettuce, was treated with non-thermal atmospheric pressure gliding arc (GA), tesla coil (TC) and dielectric barrier discharge (DBD) plasmas for the in vitro fungal inactivation of both mycelial growth and conidial germination. The fungus was exposed to the three plasmas individually for 5, 10, 15 and 20 min. The results showed that DBD plasma inactivated fungal growth during all exposure periods, and the highest inhibitory effect was caused by exposure to DBD plasma for 20 min, at 93.33% inhibition. The germination of fungal conidia was completely inactivated after exposure to all three non-thermal plasmas for 5 min, as observed 4 and 24 h after incubation. The pathogenesis of C. lactucae-sativa on lettuce after plasma treatments for 5 min was examined by spraying an inoculation of the treated conidia on lettuce. The results showed that all three plasmas reduced the disease incidence and severity compared to the non-treated control. Therefore, the non-thermal atmospheric pressure GA, TC and DBD plasmas have antifungal potential for the inactivation of C. lactucae-sativa, making them an interesting novel technology for plant disease control.

Synthesis and characterization of magnesium oxide nanoparticles by atmospheric non-thermal plasma jet

The invention of the system which facilitates and assures the use of atmospheric-pressure plasma technology has been used in several fields, including medicine and nanotechnology. In our work, magnesium oxide (MgO) nanoparticles (NPs) were created using a high voltage power supply of 21 ​kV at high-frequency equipment that produced a 6 ​kHz output. MgO NPs were successfully created at various times. X-Ray Diffraction (XRD) analysis showed that MgO NPs have a polycrystalline and an average crystalline size of 9.365 and 14.253 ​nm in both preparation times (10 and 12 ​min). Additionally, field emission scanning electron (FE-SEM) images show the single nanoparticles appear flake-like, with a thickness of 10 ​nm at 500 ​nm magnification and a width of 20 ​nm. Transmission Electron Microscopy (TEM) was employed to analyze the homogeneous, compact, and dense surface of the produced MgO NPs. Transmission electron microscopy (TEM) analysis showed that the MgO nanoparticle's average diameter ranged from 6 to 18 ​nm. Atomic Force Microscopy (AFM) was also used to uncover the degree of cooperation between the surfaces of MgO NPs, and the results showed a high extraordinary topographic contrast of the MgO NPs with a surface roughness of 2.170 ​nm.

Combined UV-C Technologies to Improve Safety and Quality of Fish and Meat Products: A Systematic Review.

This study aimed to identify the best UV-C combined treatments for ensuring the safety and quality of fish and meat products. A total of 4592 articles were screened in the relevant databases, and 16 were eligible studies. For fish, the most effective treatments to reduce Gram-negative and Gram-positive bacteria were UV-C at 0.5 J/cm2 + non-thermal atmospheric plasma (NTAP) for 8 min (33.83%) and 1% Verdad N6 + 0.05 J/cm2 + vacuum packaging (25.81%), respectively. An oxygen absorber with 0.102 J/cm2 was the best combined treatment, reducing lipid oxidation (65.59%), protein oxidation (48.95), color (ΔE = 4.51), and hardness changes (18.61%), in addition to a shelf-life extension of at least 2 days. For meat products, Gram-negative bacteria were more reduced by nir-infrared heating (NIR-H; 200.36 µW/cm2/nm) combined with 0.13 J/cm2 (70.82%) and 0.11 J/cm2 (52.09%). While Gram-positive bacteria by 0.13 J/cm2 with NIR-H (200.36 µW/cm2/nm), 1, 2, or 4 J/cm2 with flash pasteurization (FP) during 1.5 or 3 s, and 2 J/cm2 with FP for 0.75 s (58.89-67.77%). LAE (5%) + 0.5 J/cm2 was promising for maintaining color and texture. UV-C combined technologies seem to be a cost-effective alternative to ensure safety with little to no quality changes in fish and meat products.

Removal of free cyanide in dry-milled cassava flour using atmospheric nonthermal plasma treatment

The primary concern for the cassava industry is reducing hydrogen cyanide (HCN) in the final product to a level that meets the Codex standard. Wet milling and drying to produce cassava starch can reduce cyanide compounds to levels that are safe for human consumption and meet international regulations, but at a high cost in terms of water. The purpose of this study was to investigate the effect of atmospheric nonthermal (ANT) plasma treatment on the removal of free cyanide from dry-milled cassava flour, as well as other physical and chemical properties. To generate cold plasma, helium was used as the feed gas in a dielectric barrier discharge reactor. The results show that the first-order kinetic model can explain the fraction degradation of cyanide by ANT plasma. The rate of HCN fraction removal increased from 0.0116 min−1 to 0.0453 min−1 and 0.0119 min−1 to 0.0349 min−1 with increasing voltage level (10–20 kV) when the initial HCN were 143 ± 7 and 233 ± 5 mg kg−1 dw, respectively. The 20 kV-15 min ANT plasma treatment of cassava flour containing 143 ± 7 mg kg−1 dw reduced 35.7% of HCN without affecting starch crystallinity, protein, fiber, fat, or moisture content, but significantly changed the pasting properties (P < 0.05).

Hierarchical Structures Formed in an Atmospheric Pressure Plasma Jet by Polymerization from an Aerosol of Oxalic Acid Stabilized WO3–x Nanosheet Colloids: Toward High-Performance Electrochemical Devices and Sensors

The development of microstructures which combine high total surface area and high porosity is crucial for technologies such as electrocatalysis, electrochromics, and sensors. High deposition rate, composition control of deposition, and low processing temperature to retain active compositions are also desirable. To this end, this study describes combining colloidal sol chemistry with a nonthermal atmospheric pressure dielectric barrier discharge plasma jet to print hybrid inorganic/organic tungsten trioxide/oxalic acid (WO3–x/OA) microspheres. Injection of an aerosol of oxalic acid stabilized colloidal tungstic acid into an atmospheric pressure plasma jet results in the deposition of spherical structures in which the colloid is trapped within a plasma-polymerized organic shell. Subsequent low-temperature sintering produces hierarchical spherical shell-like structures comprising tungsten oxide nanosheets. Alteration of the gas flow rate changes the composition of the deposited material. The method has promise for the general preparation from colloidal precursors of porous materials of controlled morphology and composition with hierarchical microstructures, such as are required for applications in electrochemical devices and sensors which need a high ratio of surface area to volume and connectivity throughout the structure, yet also need a microstructure which is open for rapid exchange of reactants.