Plasma Scalpels: Devices, Diagnostics, and Applications

Abstract

The plasma scalpel is an application of gas discharges in electrosurgery. This paper introduces the device structure and physicochemical parameters of the two types of plasma scalpels, namely, a single-electrode Ar discharge device (argon plasma coagulation) and a two-electrode discharge device in normal saline. The diagnostic methods, including the voltage and current characteristics, optical emission spectroscopy, electron spin resonance, and high-speed imaging, are introduced to determine the critical process parameters, such as the plasma power, the gas temperature, the electron density, and the density of active species, and study the ignition dynamics of the plasma discharges in water. The efficacy of the plasma scalpel is mainly based on the physical effects of the electric current and electric field, in addition to the chemical effects of high-density energetic electrons and reactive species. These two effects can be adjusted separately to increase the treatment efficacy of the plasma scalpel. Specific guidance on further improvements of the plasma scalpel devices is also provided.

Keywords: argon plasma coagulation; diagnostics; discharge in saline; plasma scalpel; surgery.

Figure 1

The structure and working diagram of a typical plasma scalpel. (a) Argon plasma coagulation (APC) with one power electrode inside the argon flow tube and the other distal ground electrode. (b) The plasma scalpel with the power and ground electrode inside the operation handle generates plasma in the saline. (c) Various plasma scalpels manufactured by Jiangsu Bonss Medical Technology Co., Ltd. (Taizhou, China).

Figure 2

Plasma is generated in the water-vapor layer on the powered electrode.

Figure 3

Schematic of the plasma diagnostics system for plasma scalpel Reproduced with permission from Ref. [8]. Copyright (2020) IOP Publishing, Ltd.

Figure 4

(a) OES of the plasma scalpel from 305.5–312 nm. The simulation of spectra by LIFBASE is also shown. (b) Voigt fitting of Hα line measured in the plasma. The fitting FWHM of Stark broadening is 0.208 nm, and the calculated electron density is 7.1 × 10¹⁵ cm⁻³. Reproduced with permission from Ref. [8]. Copyright (2020) IOP Publishing, Ltd.

Figure 5

Vaporization dynamics of the plasma scalpel. On the right is the current waveform of three stages. Reproduced with permission from Ref. [8]. Copyright (2020) IOP Publishing, Ltd.

Figure 6

The schematic diagram of the thermal effect of the plasma scalpel.

Figure 7

The chemical mechanism of the plasma scalpel inducing collagen fragmentation. Carbon-nitrogen cleavage occurs via OH extraction of hydrogen, hydroxylation of carbon, and hydrolytic cleavage of C-N bonds.

Figure 8

Chemical mechanism of collagen scission by the plasma scalpel through OH abstraction, hydroxylation of carbon, and oxidative cleavage of C-C bonds.