Ti100 series thermal imaging cameras

After the plasma was exposed for 10 min in water, the ion analysis, pH and temperature of the water were measured using a Thermo Scientific™ Dionex™ ion chromatography (IC) system, a pH meter (Eutech Instruments, Singapore) and an Infrared (IR) camera (Fluke Ti100 Series Thermal Imaging Cameras, UK). All measurements were carried out in triplicate.

The microwave signal was detected using a horn antenna (WR-284) with a cutoff frequency of 2.14 GHz. All signals were recorded using a four-channel oscilloscope (Wave Master 8620A, LeCroy Corporation, Chestnut Ridge, NY, USA), as shown in Fig. 2, in an electromagnetically protected screen room. The microwave envelope signal was recorded by a crystal detector (Narda 4503A, Narda Miteq, Hauppauge, NY, USA). The magnitudes of the frequencies were calculated by fast Fourier transformation. Two home-made probes, not shown in Fig. 1, which we call C-dot and B-dot probes, were used to measure the diode voltage and the diode current, respectively^{45 (link)}. The C-dot and B-dot probes are connected from the microwave generator to the four-channel oscilloscope.Figure 2

Physical characteristics of the PMR apparatus. (a) Typical waveform of the diode voltage, diode current, and microwave envelope signals, (b) microwave signal, (c) dominant frequency of the microwaves, and (d) temperatures of the saline after the different PMW exposure (the room temperature was 25 °C).

After different microwave exposure, i.e., 40, 60, and 80 discharges, the temperature of the saline was measured using an Infrared (IR) camera (Fluke Ti100 Series Thermal Imaging Cameras, UK). The temperature was measured by placing the saline in the treatment room of 25 °C.

After exposure, the pH and temperature of the sample were measured using a pH meter (Eutech Instruments, Singapore) and an Infrared (IR) camera (Fluke Ti100 Series Thermal Imaging Cameras, UK).

After exposing the water samples for 10 min to either N₂, N₂ + H₂O vapor or N₂ + HNO₃ vapor plasma (at different wt% of HNO₃, i.e., 0.5, 1 and 3 wt%), the pH and temperature of the sample were measured by a pH meter (Eutech Instruments, Singapore) and an Infrared (IR) camera (Fluke Ti100 Series Thermal Imaging Cameras, UK). Simultaneously, the RONS contents in the water samples were also analyzed. The amounts of OH and H₂O₂ were measured by previously described methods^{32 (link),33 (link)}. The concentration of NO₂⁻ was measured using the Griess reagent kit (Molecular probe, USA) and the NO₃⁻ concentration was measured with an Acorn ion Meter (Oakton WD-WD-35613-30 Ion 6 meter).
To prepare the PTW, 2 ml of DI water was treated with plasma for 10 min in a 12-well plate, keeping 5 mm distance between the nozzle of the plasma jet device and the liquid surface. To determine the colony forming unit, gene expression, cell morphology and DNA damage, we used 1 ml PTW generated by the different plasma conditions, i.e., N₂, N₂ + H₂O vapor, and N₂ + 0.5 wt% HNO₃ vapor. The reason why we used the 0.5 wt% HNO₃ vapor in our further experiments on the antibacterial efficacy (instead of 1 and 3 wt%) is explained below.

DMEM media in a 6-well plate (2 ml per well) were exposed for 0 and 3 min at 200 and 400 SCCM O₂ flow rates, respectively. After exposure, the pH and temperature of the media were measured using a pH meter (Eutech Instruments, Singapore) and Infrared (IR) camera (Fluke Ti100 Series Thermal Imaging Cameras, UK).