Antimicrobial surface coatings function as a contact biocide and are extensively used to prevent the growth and transmission of pathogens on environmental surfaces. Currently, scientists and researchers are intensively working to develop antimicrobial, antiviral coating solutions that would efficiently impede/stop the contagion of COVID-19 via surface contamination. Herein we present a flavonoid-based antimicrobial surface coating fabricated by laser processing that has the potential to eradicate COVID-19 contact transmission. Quercetin-containing coatings showed better resistance to microbial colonization than antibiotic–containing ones.

We report a novel approach to the instantaneous photoinitiated synthesis of mixed anatase-rutile nanocrystalline TiO2 thin films with a three-dimensional nanostructure through pulsed white light irradiation of photosensitive Ti-organic precursor films. Pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization occurred to form graphitic oxides-coated TiO2 nanograins. Subsequent pulsed light irradiation working as in situ pulsed photothermal treatment improved the crystalline quality of TiO2 film despite its low attenuation of light. The non-radiative recombination of photogenerated electrons and holes in TiO2 nanograins, coupled with inefficient heat dissipation due to low thermal conductivity, produces enough heat to provide the thermodynamic driving force for improving the crystalline quality. The graphitic oxides were reduced by pulsed photothermal treatment and can be completely removed by oxygen plasma cleaning. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides as well as TiO2 nanocrystalline thin films.

High-energy flash cure lamps process thick film materials (<10 um) over large areas (<100 cm2) within milliseconds and are capable to deliver higher energy and power densities (20 J/cm2 and 20 kW/cm2) allowing for a more complete curing and elimination of flaws that would exist in conventional treatment. Click reactions are especially attractive for patterned devices as they have minimal shape change during curing and have a more predictable structure compared to free radical acrylate polymerization. Pentaerythritol tetrakis(3-mercaptopropionate) and 2,4,6-Triallyloxy-1,3,5-triazine were combined at 3:4 by weight and then spin coated on copper foil substrates. The solutions were processed both thermally and with exposure to a xenon flash bulb. Thermal treatment consisted of heating the sample at 80°C on a hot plate over night. Flash curing was accomplished using a Novacentrix Pulseforge 1300 system. The flash lamp curing fluence and intensities were varied to determine their effects on degree of cross-linking, dielectric constant, breakdown field and energy storage. The degree of cross-linking was determined through comparative FTIR studies. Dielectric constant was measured using an Agilent 4294a impedance analyzer from 100 Hz-100 MHz with a two terminal setup. Breakdown strength and energy density measurements were taken using Radiant Technology's Precision Ferroelectric tester with a 10 kV source. The printed films averaged 1-3 microns thick as observed by an SEM cross section measurement. It was found that dielectric constant varies with both treatment intensity and fluence. Energy densities were calculated using the ideal capacitor equation and ranged from 1.5-4.8 J/cm3.

Fifteen years ago, the field of cell and organ printing began with a few research groups looking to take newly developed direct-write tools and apply them to living cells. Initial experiments demonstrated cell viability and functionality post-deposition. Recently, research has begun in earnest to create three-dimensional cellular constructs that mimic both the heterogeneous structure and function of natural tissue. Several companies are now marketing cell printers, expanding access to a wider group of scientists and accelerating the pace of development. This article describes the past decade and a half of research by showing examples of some of the most sophisticated work, comparing the approaches and tools used in the field, and predicting the products that will arrive in the not too distant future.

The kinetics of hydrogen in preparing amorphous boron carbide (a-B5C:H) thin films was studied. The hydrogen concentration of a-B5C:H thin films formed by plasma-enhanced chemical vapor deposition (PECVD) from a single-source precursor (o-B10C2H12) is ∼35–50 at.% as determined by nuclear reaction analysis. The hydrogen concentration of the a-B5C:H thin films is an exponential function of the precursor flux during the deposition. After annealing, the hydrogen concentration in the a-B5C:H thin films decreases with the increasing annealing temperature. The kinetics of hydrogen removal during annealing is controlled predominantly by its dissociation from PECVD radicals in the a-B5C:H thin films. The activation energy of about 0.14 eV is related to hydrogen dissociation from B–H bonds, but higher activation energy (∼0.44 eV) is required to strip the hydrogen atoms from C–H bonds in the thin films.

Permalloy particles were fabricated by pulsed excimer laser ablation in distilled water and Tween 80 aqueous solution with the same laser parameters. Nearly spherical particles and irregular and porous fragments were obtained in water due to rapid condensation and growth of the laser ablated clusters. The products obtained in Tween 80 aqueous solution contained well-shaped spheres but some were laser sintered together via laser-particle interactions. Holes or pits were observed on the surface of some particles, which we consider were caused by laser induced bubbles in the liquid. Our results demonstrate the rich environment ablation in liquids can be for novel particle formation.

Electric Cell-Impedance Sensing (ECIS) is a real-time transduction system that can be used to detect the presence of foreign particles or pathogens by measuring the changes in impedance or resistance of a cell monolayer grown on an electrode. Herein, we present the use of ECIS for the detection of the toxicity of silver nanoparticles on Madine Derby Canine Kidney (MDCK) epithelial cells as a function of changes in the cell confluence and barrier function of the cell monolayer. The barrier function is a measure of the number of tight junctions formed between confluent cells in a monolayer; tighter confluence leads to an increase in a barrier function and thus in the measured resistance. We were able to detect exposures as low as 1 μg of 20 nm silver nanoparticles per 105 cells within 2 hours; those exposures were quantified as a significant drop in impedance and a gradual decrease in the barrier function as compared to the controls. Future work would include the detection of protein toxins using impedance sensing as well as further analysis of the barrier function using fluorescent staining.

Boron carbon nitride (B-C-N) thin films are attractive due to their potential as hard coatings and as semiconductors with varying band gap. Both B-C-N (BC0.24N0.24) thin films and boron carbide (B4C) thin films were deposited by radio-frequency magnetron sputtering at room temperature. Also, the transition of boron carbide to B-C-N was studied by bombarding the boron carbide thin film by ∼1 uA/cm2 4 keV N+ ions. The results show that the UV-Vis transmittance of B-C-N thin films is better than that of amorphous boron carbide and both B-C and B-N bonds exist in our B-C-N thin films. The nitrogen in our B-C-N thin films bonded with boron causes the XPS B 1s core level to shift 2 eV from that in the B4C boron carbide thin film. Ion bombardment shows that the N+ ion primarily reacts with boron to form B-N and this reaction causes the environmental change of carbon in the thin film and then the XPS C 1s core level to shift to 283.5 eV from 282.8 eV.

Permalloy (Ni81Fe19) nanoparticles with diameters of hundreds of nanometers have been successfully fabricated by pulsed laser ablation (PLA) in air, distilled water, pure ethanol and sodium dodecyl sulfate (SDS) aqueous solutions. The permalloy nanoparticles made in SDS solutions are typically spherical in shape. Lower laser energy with lower frequency leads to the formation of smaller permalloy nanoparticles. Higher concentration of SDS results in smaller nanoparticles. Lastly, we found some unusual permalloy nanoparticles with interesting morphologies made by PLA in air, distilled water and ethanol.

We have demonstrated microscale patterning of biotin and streptaividin proteins using an athermal rapid prototyping process based on piezoelectric inkjet technology. A MEMS-based piezoelectric actuator was used to dispense picoliter quantities of fluid through micron-sized nozzles. Atomic force microscopy and Fourier infrared spectroscopy studies were performed on CAD/CAM deposited proteins that were prepared using several firing voltages. Our results indicate that piezoelectric inkjet deposition is a powerful non-contact, non-destructive process for developing high-throughput biological microarrays for use in biosensing, cell culturing, and tissue engineering.

We have demonstrated deposition of dexamethasone thin films via matrix assisted pulsed laser evaporation (MAPLE). Infrared analysis revealed that dexamethasone thin films deposited by MAPLE and by drop casting had a similar absorbance spectra. AFM imaging of the MAPLE-deposited dexamethasone thin film revealed 2–10 μm punctuate ring-like structures. Deposited dexamethasone was tested for positive bioactivity by treating primary microglia cells with lipopolysacchride and measuring nitric oxide (NO) production. The successful deposition of dexamethasone thin films can be used on neural implants to prevent tissue injury and inflammatory response.

We have deposited poly (D, L lactic acid) (PDLLA) thin films using matrix assisted pulsed laser evaporation (MAPLE). FTIR spectroscopy revealed that the PDLLA had similar absorption bands to the dropcast material. X-ray photoelectron spectroscopy has shown that peaks corresponding to C-H, C-O and C=O represented 38.4, 30.1 and 31.4% of the C1s spectrum, respectively. XPS O1s analysis revealed that the O=C and O-C components make up 52 and 48 % of the O1s content. Atomic force microscopy revealed that MAPLE deposition provides smooth, continuous thin biomaterial films. These matrix assisted pulsed laser evaporation-deposited biomaterial thin films may serve to improve the implant/tissue interface.

High quality Sn-doped In2O3 (ITO) thin films have been grown by pulsed laser deposition (PLD) on glass, flexible polyethylene terephthalate (PET) and single crystal yttria stabilized zirconia (YSZ) substrates for use in organic light emitting diodes (OLEDs). Critical electrode issues for the OLED are related to the optical transparency, electrical resistivity, work function and surface roughness of the ITO film. Our research has focused on improving the properties of the ITO film to increase the efficiency of the OLED. Films were deposited using a KrF excimer laser (248nm, 30 ns FWHM) at fluences of 2 J/cm2 at substrate temperatures ranging from 1 to 100 mTorr. For ITO films (∼ 100 nm thick) deposited at the optimized conditions, a resistivity of 4.1 × 10-4 Ω-cm, 2.2 × 10-4 Ω-cm, 1.8 × 10-4 Ω-cm was observed on PET, glass and YSZ, respectively. The average film transmission in the visible range (400 - 700 nm) was about 90 % and the film surface roughness was about 0.5 nm for the film grown on glass. The Hall mobility and carrier density for ITO films (300 nm thickness) were observed to be in the range of 28 - 34 cm2/V-s and 1.0 - 1.2 × 1021 cm-3, respectively. We have used the ITO films, deposited by PLD on glass, plastic and single crystal YSZ substrates, as an anode contact in OLEDs. The OLED device performance based on PLD ITO anodes is compared with that of the device fabricated on the commercial ITO anode.

Parmod™ is a family of materials that can be printed and thermally cured to create metallic conductors on printed wiring boards. This additive process provides a way to produce circuitry direct from CAD files without the necessity for intermediate tooling of any kind. The printed images are converted to pure metallic traces in seconds at a temperature low enough to be compatible with commonly used rigid and flexible polymer-based substrates. This simple, two-step process eliminates the hazardous wastes and employee health and safety issues associated with conventional plate-and-etch photolithographic technology

Recently the Parmod™ technology has been extended from metals to oxides to enable printing passive electronic components such as resistors, capacitors and inductors, as well as the metallic interconnects. While thermal curing of the oxides provides useable electronic properties, particularly of resistors and capacitors, the performance of all these novel materials could be improved by laser processing. This paper discusses preliminary results on laser processing of Parmod™ conductors and components in two different systems

BaxSr1−xTiO3 (BST, x=0.5 and 0.6) thin films have been deposited onto (100) MgO single crystal substrates by pulsed laser deposition (PLD). The room temperature capacitance and dielectric quality factor (Q=1/tanδ have been measured as a function of electric field (≤ 100 kV/cm) at microwave frequencies (1 to 20 GHz) using silver interdigitated electrodes deposited on top of the BST film. It has been observed that the dielectric constant of the film and its change with electric field are closely related to film phase (amorphous to crystalline phase) and film strain which affects the ionic polarization of the film. Amorphous BST films show high dielectric Q (> 100) with low dielectric constant (∼30–200) and low dielectric tuning (< 1%), presumably due to small ionic polarization. Crystalline films have a higher dielectric constant (∼1000–3000) and a higher dielectric tuning (∼ 65%) but a lower dielectric Q (∼20). As an optimal microstructure of the film for tunable microwave applications, strain-relieved large-grained (∼5000 Å) randomly oriented polycrystalline films were deposited using a thin amorphous buffer layer of BST (∼50 Å). Very large grains (size up to a few microns) were observed in BST films prepared using a thicker amorphous buffer layer (∼500 Å). We will present results on how careful control of microstructure can lead to films with optimal dielectric properties for the tunable microwave devices.

Single phase, (001) oriented SrBi2Ta2O9(SBT) thin films have been deposited on (100) MgO substrates using pulsed laser deposition(PLD) technique. In order to study the influence of the growth conditions on the microstructure and stoichiometry, SBT film growth was carried out under different deposition conditions, using an Kr:F excimer laser (248 nm, 30 ns FWHM). Effect of laser fluence(0.75–2 J/cm2), frequency of the laser pulse (4–10 Hz), substrate temperature (700–850°C), oxygen partial pressure(150–450 mTorr) have been studied using X-ray diff-raction(XRD), Scanning Electron Microscope(SEM), X-ray energy dispersive analysis (EDAX), atomic force microscopy(AFM). It was found that small variation in growth temperature and oxygen pressure has a large influence on the average grain size (50–180 nm) and surface roughness (0.14–0.3 nm) respectively. Outgrowths on the film surface were observed at high substrate temperatures, high laser energy and with higher frequencies (>6) of the laser pulse. Highly c-axis oriented SBT thin films with homogeneous surface morphology and with an average surface roughness of 0.14 nm were deposited at 750 °C, 260 mTorr O2 pressure and 1.25 J/cm2 laser fluence. These films have a tangent loss around 0.05 and dielectric constant around 417 with a tunability of 4% in the microwave frequency region (1–20 GHz).

Single phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

Single phase BaxSr1−xTiO3 (x=0.5 and 0.6) thin films (∼5000Å thick) have been deposited onto (100) MgO single crystal substrate with (Ba,Sr) compensated and/or (Mn,Fe,W) doped targets using pulsed laser deposition (PLD). The room temperature capacitance (C) and dielectric Q (1/tanδ) have been measured at microwave frequencies of I to 20 GHz as a function of electric field (0-80kV/cm). Microstructural defects associated with cation and anion vacancies have been observed in BaxSr1−xTiO3 films. Compensation of the ablation target with excess Ba and Sr tends to increase the dielectric constant and the dielectric Q. A film deposited with (Ba,Sr) compensated target has been obtained with 25% tuning, where % tuning is defined as {(C(0)-C(E))/C(O))×100, and dielectric Q of ∼ 100 at room temperature (1 — 10 GHz) for DC bias field (E=67 kV/cm). A further increase in the dielectric Q is observed by the addition of donor/acceptor dopants such as Mn, Fe, and W (Q≈100-240). The effects of (Ba, Sr) compensation and (Mn,Fe,W) doping on the film structure and dielectric properties are discussed.

KTa1−xNbxO3 (KTN) thin films (-6000 Å) were grown on (100) MgO, (100) LaAlO3 (LAO), and (100) SrTiO3(STO) substrates by pulsed laser deposition (PLD). Deposited films were smooth, single phase and exclusively (100) oriented. KTN films deposited on MgO and LAO substrates were easily cracked after deposition or post deposition heat treatment. The film deformation appeared to be caused by strain due to the lattice mismatch between the film and the substrate. A thin buffer layer of ∼100 Å was used to eliminate the cracking problem. The high volatility of K at the film deposition temperature required excess K to be added to the ablation target. Sintering of the target and post-deposition annealing of the films were done in a sealed Pt coated stainless steel container. Rutherford backscattering showed the films to have a 1 to 1 atomic ratio of K to Ta + Nb. On top of the KTN films, Ag interdigitated capacitors were deposited. Room temperature measurements of capacitance and dielectric loss as a function of bias electric field (0 -80 kV/cm) at 1 to 20 GHz were made. Capacitance and dielectric loss measurements were made as a function of temperature and bias electric field at one MHz and as a function of temperature and frequency at 0V DC bias. The results show the strong potential of KTN for use in frequency agile microwave electronics.

Single phase, (100) oriented Ba0.5Sr0.5TiO3 films have been deposited by pulsed laser deposition onto (100) LaAIO3, SrTiO3, MgO substrates. The dielectric properties of these films were measured using interdigitated capacitors as a function of DC bias and temperature at 1 MHz and as a function of DC bias at 1 to 20 GHz at room temperature. Deposited films were annealed over a temperature range of 900 to 1350 C for 1 to 8 hours to observe its effect on dielectric properties. Chemical analysis on films deposited from stoichiometric targets showed the films to be up to 6% deficient in Ba and Sr under typical PLD deposition conditions. Optimal annealing conditions and target stoichiometries for minimizing dielectric loss and maximizing tuning are discussed.