Subgroup 4 – Atmospheric-Pressure Plasma Application Group: Biomedicine, Agriculture, & Industry
Applications of atmospheric-pressure plasma (APP) in bio-medical field has attracted tremendous attention recently due to its excellent capability in generating high electric field, radicals, UV emission and charged particles. In this group, our major goal is to design portable APP devices for many practical biomedical applications by collaborating closely with medical doctors. Currently, we focus on treating skin related diseases, which include infected wound healing, skin regeneration, gray nail, and green nail, to name a few. In addition, we also collaborate closely with other groups in our department in dealing with dental related research, e.g., tooth bleaching and pulp stem cell regeneration, and cancellous bone sterilization. We have also developed an efficient two-step procedure, which includes nitrogen and ammonia plasma, to treat plain or honeycomb polymer such as PLA to enhance its bio-compatibility for better cell attachment and growth. In addition, an aerosol-assisted DBD APP deposition system, which combines plasma polymerization and surface modification in a single-step process to immobilize the biomolecules in the deposited thin film. Potentially, it can be used to fabricate biosensors, drug delivery system and food additives. In our group, we have developed two major types of round APPJs using either argon or helium as the discharge gas. These APPJs are carefully characterized electrically and optically using I-V probe and OES/ICCD and UV absorption technique respectively.
AP plasma source
The APPJ device consists of a quartz tube, stainless steel tube with an aluminum stepped convergent-divergent nozzle (powered electrode), and an aluminum foil (ground electrode).
The APPJ system consists of four parts: gases feeding system, AC power supply, optical emission spectroscopy, plasma source holders and electrode arrangement. The argon APPJ device consists of two outer copper tubes separately on the outer surface of quartz tube as power and ground electrodes, a slender copper tube inserted in the quartz tube and the quartz tube is dielectric, which are covered by an out-casing made by ABS material. Argon with different amounts of carrier gases, such as oxygen or water vapor, flow through the round tube as the discharge gases. The gas jet temperature is approximately 35℃ which is very close to human body’s skin temperature; thus, it can be applied directly in contact with human body without any safety concern.
The APPJ device consists of a quartz tube, a special stainless steel structure with a small part of platinum as power electrode, and an aluminum foil wrapped outside the quartz tube as ground electrode. This APPJ device is driven by a sinusoidal power supply at the frequency of between 16-24 kHz. Nitrogen-based carrier gases can be injected into the chamber and generate plasma through applied high voltage. With a proper control of operating condition, the plasma plume can be up to 10-30 mm, which may have many potential applications in bio-medical fields, such as bacterial inactivation, skin regeneration, and wound healing, among others.
Planar nitrogen-based atmospheric- pressure dielectric barrier discharge (DBD) jet
The nitrogen-based planar DBD APPJ with various lengths of electrodes (0.1–5 cm) with a fixed gas flow rate of 50 slm. This APPJ was driven by a quasipulsed power source with a frequency of 60 kHz and a voltage amplitude of 8.8 kV. This device was used for sterilization and surface modification (PLA, PP, PET film).
Aerosol-assisted atmospheric pressure plasma system
The aerosol-assisted atmospheric-pressure planar dielectric-barrier-discharge-type plasma deposition (AA-APPD) system can polymerize monomers and immobilize biomolecules simultaneously. It can successfully deposit and immobilize Lyz biomole- cules using DI-water and PBS aerosols at three different temperature (10 °C, 20 °C, and 40 °C), in a single step operation. Also, the lipase-PPE coatings embedded the lipase through the AAAPPD system successfully. Moreover, this system improved the adhesion of AAAPPD protein-PPE coatings on substrate and provides a cost-effective way for protein entrapment on substrates.
Plasma activated water generation system
This plasma generator consisted of a converging quartz tube as the dielectric material, a platinum wire which was welded at the tip of a stainless steel screw as the power electrode, and an aluminum foil, which was wrapped around outside the quartz tube as the ground electrode. A ceramic tube was placed near the exit of the quartz tube to prevent from arcing. The following figure shows the visualization of air and oxygen plasma generating in RO water respectively.
The combination of UV, reactive species, charge particles, and drastic chemical reactions of plasma provides a promising tool in biomedicine. In our lab, we focus on cell culture on plasma-treated biomaterial surface (PLA, PP, PET, and stainless steel), sterilization on agar plates or green/grey nails, monomers polymerization and biomolecules immobilization, and wound healing of rats.
Helium Plasma Jet on Sterilization (Chih-Tung Liu et al, IEEE Transactions on Plasma Science, Vol. 44, Issue 12, pp. 3112–3116, 2016)
Argon Plasma Jet on Sterilization (Z.-H. Lin et al, IEEE Transactions on Plasma Science, Vol. 44, Issue 12, pp. 3140–3147, 2015)
SEM Images of Plasma Sterilization (Z.-H. Lin et al, IEEE Transactions on Plasma Science, Vol. 44, Issue 12, pp. 3140–3147, 2015)
Surface morphology of different conditions of AA-AAPD system for understanding the surface properties and roughly showing the uniformity. The shape of the Lyz and NaCl particles was spheroidal shape and cubic shape in the SEM images, respectively. (Chun-Ping Hisao et al, IEEE Transactions on Plasma Science, Vol. 44, Issue 12, pp. 3091–3098, 2016)
Inverted contrasting microscope observation of cells on pure, gelatin coated and 2-step plasma treated PLA films during three-day test period. (Y.-W. Yang et al, Journal of Biomedical Materials Research Part A, Volume 102, Issue 1, pp. 160–169, 2014)
Improvement of Acute Wound Healing Using Argon Plasma Jet (Z.-H. Lin et al, Plasma Medicine, Volume 7, Issue 3, P. 227-243, 2017)
Accelerated Small Size Diabetic Wound Healing Using Argon Plasma Jet (Kuang-Yao Cheng et al, Scientific Reports, 2018)
Improvement of Large Size Diabetic Wound Healing Using Argon Plasma Jet (Kuang-Yao Cheng et al, Scientific Reports, 2018)
Self-Organized Honeycomb Structure on Polylactide Surface and Enhancement of Cell Growth Using Planar Nitrogen Plasma Jet (Kuang-Yao Cheng et al, Applied Surface Science, Vol. 394, pp. 534–542, 2017)
Left: teeth before treatment; right: teeth after 20 min of treatment with (a) He flow, (b) H2O2 gel, and (c) He-APPJ with saline solution (Yun-Chien Cheng et al, Plasma Processes and Polymers, Volume 14, 201600235, 2017. ) This research was cooperated with Dr. Yun-Chien Cheng and reported by Advanced Science News.
Since either atmospheric-pressure plasma jets or atmospheric-pressure activated water can generate all kinds of ROS, it is highly attractive to apply them to sterilize some plants (e.g., vegetables) and fruits (e.g., mongo) and stimulate the growth rate of plants (e.g., mushroom, vegetables), to name a few. In our laboratory, we have been working closely with many professors and local biotech company in agriculture field to advance the understanding of the plasma effect and application in this emgerging field.
Atmospheric air plasma has been widely used in industry applications like creating the hydrophobic or hydrophilic surfaces on metals, plastics, glasses or polymers. It has several advantages as follows: no need for expensive vacuum system, low-cost, non-polluted and convenient operating.
OES distribution (400–700 nm) for different discharge gases of a N2-based APPJ (M.-H. Chiang et al,, IEEE Transactions on Plasma Science, Vol. 38, Issue 6, pp. 1489-1498, 2010)
Measured contact angle of ITO glass surface (stationary) as functions of z coordinate and O2/N2 (%) after 5 s of plasma jet treatment (60 kHz, 50 SLM, 175 W) (M.-H. Chiang et al, Plasma Chemistry and Plasma Processing, Vol. 30, Issue 5, pp. 553-563, 2010)
Measured contact angle of ITO glass surface (non-stationary) as functions of z coordinate and O2/N2 (%) after a pureN2 and 0.04%O2/N2 plasma jet treatment (M.-H. Chiang et al, Plasma Chemistry and Plasma Processing, Vol. 30, Issue 5, pp. 553-563, 2010)
Surface roughness analysis of pure, pretreatment plasma (0–1% oxygen), ammonia plasma (0–10% ammonia), and optimized two-step plasma (0.1% oxygen; 5% ammonia) treated PLAs. (Y.-W. Yang et al, Plasma Processes and Polymers, Vol. 12, Issue 7, pp. 678–690, 2015)
Equivalent Circuit Modeling
Use software to simulate equivalent circuit model of plasma, to predict energy consumed, electrical characteristics…etc. under different parameters. As a reference to develop new device or find out the best parameter combination.