Table 4.

Characteristics of plasma devices.

Authors	Plasma Device Description	Pulse Frequency	Pulse	Flow Rate	Gas	Plasma Temperature	Application Distance	Application Time	Total Energy	Power	Manufacturer
Choi B.B. et al., 2012 [37]	air-NTP: the size of the device is 10.24 cm2. The mask pattern was etched by wet etching technique on the Cu electrodes which is surrounding both side of PTFE dielectric surface.	22 kHz	15 kV	N/P	Air	N/P	2 mm	30 s	9.2 J/cm2	3.15 J/s	Pohang University of Science and Technology, Pohang, Korea (Kim et al., 2010 [88])
Han X. et al., 2013 [23]	N-APPJ: Two copper ribbon electrodes of 0.6 mm thick separated by 1.8 mm are wrapping around a quartz tube (outer diameter: 3 mm). One helical electrode is connected to a HV power supply, and the other is grounded. The electrode wrapping zone has a vertical length of 35 mm.	28 kHz	22.4 kV (Vrms. 7.75 kV) 59 mA (Irms. 17 mA)	1.5 L/min	N2	N/P	20 mm	10, 30, 60, and 120 s	N/P	N/P	N/P
Chang J.W. et al., 2014 [36]	He+O-NTP spray type: arc-free and antistatic plate to provide a uniform plasma jet.	20–30 kHz	2–13 kV	N/P	He/O2	N/P	N/P	1 s	N/P	N/P	Pohang University of Science and Technology, Pohang, Korea
Guerrero-Preston R. et al., 2014 [5]	He-CAP: The CAP device contains 4 blocks. Block 1 is a DC power supply. Block 2 is a centrally powered electrode with a ground outer electrode wrapped around a quartz tube. Block 3 consists of a capacitor, a transistor, and a timer; block 4 is the He gas supply.	N/P	8 kV	10 L/min−1 test and 20 L/min−1 positive treatment control	He	N/P	3 cm	10, 30 45 s and 10 s for control	N/P	N/P	School of Engineering and Applied Science of The George Washington University
Kang S.U. et al., 2014 [73]	He + O NTP spray-type: NTP with a newly designed arc-free and antistatic plate to provide uniform NTP for biological research applications. The plasma source is equipped with a pair of electrodes that is made of Al2O3 (high voltage and ground electrodes, 1040 mm2 dimension, 2 mm gap between electrodes) that is isolated from direct contact with the plasma by a ceramic barrier.	20–30 kHz	2–13 kV	N/P	He/O2	35 °C	In vitro: 3 cm In vivo: 1 cm	In vitro: N/P In vivo: 20 s	N/P	N/P	N/P
Kim S.Y. et al., 2015 [74]	LTP produced by He + O-NTP spray-type: newly designed arc-free and antistatic plate to provide uniform NTP. The plasma source is equipped with a pair of electrodes made of Al2O3 (high-voltage and ground electrodes, 10 × 40 mm2 in dimension, 2 mm gap between electrodes) isolated from direct contact with the plasma using a ceramic barrier.	20–30 kHz	2–13 kV	N/P	He/O2	35 °C	1–2 cm from the culture media	in vitro: 15 min. syngenic tumor model: 1 week. xenograft model: 10 times.	N/P	N/P	N/P
Metelmann H.R. et al., 2015 [85]	kINPen MED: Hand-held unit discharges plasma under atmospheric conditions, requiring a DC power unit and Ar gas reservoir. In the center of a ceramic capillary (inner diameter 1.6 mm) a pin -type electrode (1 mm diameter) is mounted. The needle is powered by a miniaturized RF generator.	1 MHz, modulated with 2.5 kHz and plasma duty cycle of 1:1.	Sinusoidal voltage waveforms range from 2 kV to 3 kV amplitude peak.	5 slm	Ar	38 °C	Spot exposure of the ulceration to CAP from 8 mm.	Cycles of 3 single treatments within 1 week, followed by an intermittence of 1 week without CAP exposure. Repeatedly scanning tumor ulceration accessible area for 1 min/cm2. Total treatment time increase to more than 30 min for patients with large ulceration exceeding 30 cm2.	N/P	N/P	Neoplas tools GmbH, Greifswald, Germany
Welz C. et al., 2015 [82]	air-CAP: MiniFlatPlaSter is equipped with a high voltage power supply, accumulators, and a SMD electrode for production in air. The SMD electrode consists of a copper foil layer (around 0.2 mm thick), an Epoxy board (1 mm thick), and a stainless-steel mesh of 28 mm in diameter, so that it exactly fits the rim of one well.	6.75 kHz	7 kV	N/P	Air	N/P	17.5 ± 0.5 mm	30, 60, 90, 120 and 180 s	N/P	N/P	FlatPlaSter, Regensburg University Hospital
Lee J.H. et al., 2016 [75]	N-CAP jet: made up of an inner electrode made of tungsten with 1.2 mm depth and 0.2 mm thickness with 3.2 mm depth of quartz as a dielectric. The hole in the outer electrode made of stainless steel was 0.7 mm via the 2 mm height of porous alumina having a 150~200 μm pore size with 35% porosity.	60 Hz	1.2 kV	250; 500; 750; 1000; 1500; 2000 sccm	N2	N/P	8 mm	1 min	0.51; 0.62; 1.98; 2.91; 2.4; 2.33 W	N/P	Kwangwoon University
Schuster M. et al., 2016 [87]	kINPen MED: Hand-held unit discharges plasma under atmospheric conditions, requiring a DC power unit and Ar gas reservoir. In the center of a ceramic capillary (inner diameter 1.6 mm) a pin -type electrode (1 mm diameter) is mounted. The needle is powered by a miniaturized RF generator.	1 MHz, modulated with 2.5 kHz and plasma duty cycle of 1:1. Amplitude peaks at a frequency of 1 MHz and modulated with 2.5 kHz.	Sinusoidal voltage waveforms range from 2 kV to 3 kV amplitude peak.	N/P	Ar	N/P	Spot exposure of the ulceration to CAP from a distance of 8 mm	Group 1: cycle of 3 single treatments within 1 week for 1 min, followed by an intermittence of 1 week without CAP exposure. Group 2: one-time application for 3 min followed by total resection of the tumor.	N/P	N/P	Neoplas tools GmbH, Greifswald, Germany.
Metelmann H.R. et al., 2018 [15]	kINPen MED: Hand-held unit discharges plasma under atmospheric conditions, requiring a DC power unit and Argon gas reservoir. In the center of a ceramic capillary (inner diameter 1.6 mm) a pin -type electrode (1 mm diameter) is mounted. The needle is powered by a miniaturized RF generator.	1 MHz, modulated with 2.5 kHz and plasma duty cycle of 1:1.	Sinusoidal voltage waveforms range from 2 kV to 3 kV amplitude peak.	5 slm.	Ar	38 °C	8 mm, vertically to naturally moist tissue surface.	Cycles of 3 single treatments within 1 week, followed by an intermittence of 1 week without CAP exposure. Repeatedly scanning tumor ulceration accessible area for 1 min/cm2. Total treatment time increase to more than 30 min for patients with large ulceration exceeding 30 cm2.	N/P	N/P	Neoplas tools GmbH, Greifswald, Germany.
Chauvin J. et al., 2018 [6]	PAM produced by He-CAP jet (DBD): made up of Al tape electrodes wrapped on a quartz tube with small diameters (2 mm inner diameter and 4 mm outer diameter) separated by 10 mm space.	10 kHz	10 kV square pulses	3 L/min	He	N/P	2 cm	0, 30, 60, 120, 240 s	N/P	N/P	Université de Toulouse-LAPLACE
Schuster M. et al., 2018 [86]	kINPen MED: Hand-held unit discharges plasma under atmospheric conditions, requiring a DC power unit and Ar gas reservoir. In the center of a ceramic capillary (inner diameter 1.6 mm) a pin -type electrode (1 mm diameter) is mounted. The needle is powered by a miniaturized RF generator.	1 MHz, modulated with 2.5 kHz and plasma duty cycle of 1:1. Amplitude peaks at a frequency of 1 MHz and modulated with 2.5 kHz.	Sinusoidal voltage waveforms range from 2 kV to 3 kV amplitude peak	N/P	Ar	N/P	Spot exposure of the ulceration to CAP from a distance of 8 mm.	Cycles of 3 single treatments within 1 week, followed by an intermittence of 1 week without CAP exposure, exceptionally due to the patient’s individual circumstances of 2 to 3 weeks. Repeatedly scanning tumor ulceration accessible area for 1 min/cm2.	N/P	N/P	Neoplas tools GmbH, Greifswald, Germany.
Hasse S. et al., 2019 [72]	PAM produced by Ar-CAP kINPen MED made of two electrodes, a pin type high voltage electrode inside a ceramic capillary and one grounded electrode. The plasma is generated at the tip of the pin type electrode and expanded about 1 cm to the surrounding air outside the capillary.	It generates a radiofrequency signal of about 1 MHz. The discharge is switched on at a frequency of 2.5 kHz (50:50).	2–3 kV	5 slm	Ar	35–39 °C	Medium indirect and 8 mm from tissue	In vitro: 20, 40, 80, 150 s Ex vivo: 3 min	N/P	N/P	Neoplas tools, Greifswald, Germany
Sato K. et al., 2019 [80]	Ar-NTP: 2 electrodes 20 mm apart. NTP had an ultrahigh electron density and an O density of approximately 4 × 1015 cm3.	60 Hz	10 kV	2 L/min	Ar	25 °C	8 mm	30–120 s	N/P	N/P	Habahiro instrument from Prof. M. Hori, Plasma Nanotechnology Research Center, Nagoya University, Japan.
Dai X. et al., 2020 [84]	N/P	N/P	N/P	N/P	N/P	N/P	3–5 mm	N/P	N/P	N/P	Unitec low-temperature plasma.
Han X. et al., 2020 [71]	N-APPJ: 2 copper ribbon electrodes of 0.6 mm thick separated by a distance of 1.8 mm are spirally and alternatively wrapping around a quartz tube, whose outer diameter is 3 mm. One of the helical electrodes is connected to a HV power supply and the other is grounded. The electrode wrapping zone, with a vertical length of 35 mm along the quartz tube, is the major region of plasma ignition. A wider glass tube is sealed outside the quartz tube and a fluid with a high dielectric constant was filled within the volume between these 2 tubes. When N2 is introduced into the quartz tube and HV is applied, plasma is ignited and forms a plasma jet of a few cm long to the open atmosphere.	28 kHz	22.4 kV	1.5 slm	N2	N/P	20 mm	120 s	N/P	N/P	N/P
Lee C.M. et al., 2020 [38]	Ar-CAP jet: CAP apparatus P500-SM consists of a gas supply system, MFC, a plasma jet and a high-voltage AC power supply.	20 kHz	8.5 kV	5 slm	Ar	N/P	3 cm	10 s–5 min	45 W	N/P	Sakikake Co. Ltd., Kyoto, Japan
Ramireddy L. et al., 2020 [79]	He-CAP jet: Dielectric barrier and quartz tube inner and outer diameters of 2 and 4 mm respectively. Two electrodes copper strips (grounded 2.5 cm and powered 1.5 cm) wrapped around the quartz tube. The powered electrode is 2 mm from the nozzle end and the distance between the grounded and powered electrodes is 1.5 cm.	10 kHz	7.5 kV	5 slm	He	N/P	3 cm	1, 3, 5 min	N/P	N/P	N/P
Lin A. et al., 2021 [76]	air-microsecond-pulsed DBD: plasma system (custom built): Copper electrode covered with 0.5 mm fused silica diameter 1.2 cm	0.05 kHz a 0.5 kHz.	30 kV	N/P	Air	N/P	1–10 mm	10–240 s	9.4 J	N/P	The power supply was custom built (Megaimpulse Ltd.)
Oh C. et al., 2021 [77]	NTPAM generated by NTP jet. The device is composed of a quartz tube (diameter: outer 6 mm, inner 4 mm) with two electrodes (an inner stainless-steel tube and an outer ground ring). The inner is also placed as a gas inlet.	20 kHz	Few kV	He: 4 slpm; O2: 1 sccm.	He/O2	N/P	In vitro: approximately 1 cm. In vivo: N/A	In vitro: various activation times. In vivo: 100 μL intratumoral injections of NTPAM in the experimental group administered once daily for 11 days.	Discharge power varied from 10 to 24 W.	N/P	N/P
Park J. et al., 2021 [78]	Ar-NTP: 1 dielectric and 2 electrodes. The inner is composed of stainless, the external is wrapped with copper tape. The NTP is produced between the inner and outer electrodes, and the plasma flow temperature is kept below 35 °C for 10 min.	N/P	N/P	2 slm	Ar	N/P	10 mm	5 min	N/P	N/P	Feagle Company (Yangsan-si, Kyeongsangnam-do, Korea)
Sklias K. et al., 2021 [81]	He+O-DBD micro-plasma jet: Plasma reactor: stainless-steel needle (0.7 mm inner and 1.4 mm outer diameters), inserted inside a dielectric tube made of quartz, and biased electrically by applying high voltage square positive pulses. The distance between the needle’s tip and the reactor’s nozzle is fixed (55 mm). The ground electrode (10 mm width), made of copper, is wrapped around the dielectric tube, centered at the tip of the needle.	10 kHz	Amplitude of 6 kV, pulse width of 4.8 µs, rise and fall times of around 25 ns.	0.5 slm or 1 slm	He/O2	23 °C	8 or 20 mm.	N/P	N/P	N/P	N/P
Wu C.Y. et al., 2021 [83]	N-NTP jet: Custom-made micro-plasma jet source. One capillary electrode is the jet source to inject additive N2. A stainless-steel capillary tube (diameter of 0.8 mm) at the center of the quartz tube is used as the inner electrode. This is connected to the ground and used as a N2 flow channel. A piece of copper is used as the outer electrode, which is connected to the output of the generator.	13.56 MHz	12–14 W	N/P	He/N2	37 °C	4 mm	-30, 90, 120 s. -5 min (apoptosis).	N/P	N/P	RF, ENI ACG-3B, MSK Instruments, Inc., USA

APPJ: atmospheric pressure plasma jet; Ar: Argon; CAP: cold atmospheric plasma; Cu: copper; DBD: dielectric barrier discharge; DC: direct current; ep: energy per pulse; He: helium; HV: high voltage; LTP: liquid-type NTP; MCF: mass flow controller; N: nitrogen; N/P: not provided; NTP: non-thermal atmospheric pressure plasma; O₂: oxygen; PAM: plasma activated medium; PAP: Plasma activated PBS; PBS: Phosphate buffered saline; PTFE: polytetrafluoroethylene; RF: radio frequency; sccm: standard cubic centimeters per minute; slm: standard Liter/min; SMD: surface mounted device; td: treatment distance; tt: treatment time.