Prototype of a Plasma Generator for Electrosurgery

Plasma is one of the four fundamental states of matter and consists of highly ionized particles, it means, particles highly energized. Typically, plasma can be seen in neon lights or sudden electric discharges such as lightning or sparks. These ionized particles have sufficient energy (3 - 6 eV) to break organic molecular bonds within tissue. This property has been found useful for the application of plasma in surgeries as a cutting tool. Plasma has some advantages compared with other techniques for ablation (removal of tissue by cutting, vaporization, etc.), such as scalpel or electrocautery (cutting by vaporizating tissue applying an electric current), etcThis document presents the design and construction of a plasma generator for electrosurgical applications. The generator is comprised of four main parts: DC power supply, topology push-pull, controller unit and plasma probe. First results generating plasma by repetitively-pulsed electrical discharges in sodium chloride saline solution are reported

Plasma chemical driven biomedical applications with a radio frequency driven atmospheric pressure plasma jet

2012 Fall.Includes bibliographical references.We present radio frequency driven atmospheric pressure plasma jet for various biomedical applications such as tissue removal, bacterial sterilization, and tooth whitening. Two different types of plasma assisted electrosurgery, remote electrode plasma jet and plasma jet surrounding monopolar electrosurgical electrode, were employed to enhance tissue removal in terms of less heat damage on contiguous tissue and fast removal rate. Chlorine based chemical (CHxClx) additives in argon plasma jet enhanced tissue removal rate, proportional to the Cl radical density in the plasma jet. Pulsed RF provided another knob to control the removal profile, heat damage, and removal rate. Hydrogen peroxide (H2O2) additive provided abundant OH generation in the helium plasma jet. It not only enhanced tissue removal rate but also reduced heat damage on the contiguous tissue. The tissue removal mechanism of helium-H2O2 plasma is explained based on the FTIR measurement of the tissue samples, and optical emission and absorption spectra. Hydrogen peroxide addition to argon plasma jet was employed for bacterial inactivation. Observed OH density by optical emission and absorption was proportional to the number of deactivated microorganism. Argon plasma jet in DI water also provided abundant OH on the interface of water and gas plasma. The OH radicals applied on porcine tooth sample selectively removed the stain without damaging the underlying enamel

Removal of cardiovascular obstructions by spark erosion

Coronary atherosclerosis, leading to coronary artery stenosis, is the main cause for ischemic health disease in the Westem countries. Stenoses manifest themselves by limiting blood supply to the myocardium thus causing complaints. A long history of degenerative atherosclerotic disease of the intimal wall of the coronary vessels has usually preceded these events. Probably because of this long term process the composition of the accumulated obstructive tissue is quite heterogeneous and consists of a variety of cells and extra cellular material like lipid containing macrophages, smooth muscle cells, Illonocytes, collagen. cholesterol crystals and calcium. In addition, fresh or organized thrombi may have been deposited on these plaques. Regression of these lesions may be obtained by lifestyle changes or lipid lowering therapy. The acute invasive removal of such complex lesions, however, cannot be achieved by applying simple mechanical or chemical means

Study of Plasma - Liquid Interactions

Disertační práce se zabývá detailním studiem vlastností různých elektrických výbojů generovaných ve vodných roztocích. Tyto výboje se staly v posledním desetiletí velmi populárním tématem, a to zejména díky mnoha praktickým využitím jako například v biomedicíně, čištění odpadních vod, ekologii nebo nanoinženýrství. Studium je zaměřeno na generaci peroxidu vodíku, jakožto jednu z nejvýznamnějších částic generovaných právě elektrickými výboji v kapalinách. Pro první část této práce byla využita speciální výbojová komora zkonstruovaná na Fakultě chemické Vysokého Učení Technického v Brně. Komora byla rozdělena tenkou diafragmovou přepážkou na dvě poloviny, přičemž uvnitř přepážky se nacházela malá dírka. V každé části komory se nacházela jedna elektroda, a obě dvě části komory byly vyplněny kapalinou. Ze zdroje bylo do kapaliny aplikováno vysokofrekvenční napětí (1 a 2 kHz), které tak vlastně upravovalo roztok chloridu sodného (1.5 l). Bylo zjištěno, že tento druh napětí, v porovnání s DC, nezpůsobuje nežádoucí přehřívání roztoku (počáteční vodivost 100 - 800 S/cm) během jeho úpravy při zachování účinnosti produkce peroxidu. Experimentální aparatura pro druhou část práce byla sestavena na Gentské Univerzitě v Belgii. Stejnosměrný výboj byl generován v bublinách plynů (He, Ar, N2, vzduch) v prostředí vodných roztoků. Byla studována generace peroxidu vodíku a odbourávání organických barviv přítomných ve zkoumaném roztoku. Ke generaci peroxidu vodíku byl použit roztok NaH2PO4 . 2H2O (5 microS/cm, V= 750 ml), ke zkoumání rozkladu barviv byly použity roztoky organických barviv Direct Red 79 (20 mg/l) a Direct Blue 106 (20 mg/l, V= 750 ml). Minimální koncentrace peroxidu vodíku byla naměřena při aplikaci proudu 10 mA, zatímco maximální koncentrace peroxidu vodíku byla zaznamenána při použití proudu 30 mA. Rozklad organických barviv vykazoval stejné vlastnosti. Čím vyšší byla dodávaná energie, tím více barviva se odbouralo. Třetí část práce probíhala ve spolupráci s Queen's University of Belfast, Centrum for Plasma Physics, UK. K realizaci experimentů bylo využito vysokofrekvenčního plazmového skalpelu (Arthrocar). Bylo zjištěno, že hodnota koncentrace peroxidu vodíku dosahovala maxima v roztocích s nepatrným přídavkem alkoholu (0.25 %). Celkem byly studovány čtyři 0.15 M roztoky BaCl2, Na2CO3, KCl a NaCl (V= 20 ml), jejichž počáteční vodivost se pohybovala kolem 13 mS/cm. Z výsledků bylo patrné, že největší rozdíl hodnot pH byl zaznamenán u roztoků s přídavkem ethanolu. V optických emisních spektrech byly identifikovány především radikály OH, které jsou prekurzory peroxidu vodíku. Výsledky ukázaly, že plazma v takovémto roztoku je stále tvořeno, což může být považováno za první krok generace plazmatu v organických sloučeninách. Poslední část práce byla zaměřena na tzv. mikroplazmatický jet v přímém kontaktu s kapalnou fází. Tato experimentální práce byla realizována na pracovišti Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, UK během studijní stáže. Jako vodivé médium byl použit roztok trihydrátu kyseliny chlorozlatité s různou počáteční vodivostí. Zajímavým zjištěním je fakt, že při tomto druhu měření bylo generováno stabilní plazma i při velmi malém výbojovém proudu (0.05 a 0.2 mA), a tedy i peroxid vodíku vznikal při velmi malé vstupní energii, což může být považováno za velmi dobrý výsledek.This Ph.D. thesis contains a detailed investigation of different electric discharges generated in liquids. These discharges have become a popular topic during the last decade, mainly due to many practical applications for example in biomedicine, waste water treatment, ecology and nanoengineering. The study is focused on hydrogen peroxide generation which is one of the most important particles generated by electric discharges in liquids. A special batch discharge chamber, constructed at the Brno University of Technology, Faculty of Chemistry, Czech Republic, was used for the first experimental part. This discharge chamber is separated by a diaphragm membrane with a pin hole at its centre. A single high voltage electrode is placed in each part of the chamber, which is filled by water solution. High frequency voltage (1 and 2 kHz) was used as a power source to treat a NaCl solution (1.5 l). After evaluation of all results it has been found that this kind of power supply, compared to DC, does not cause any unwanted overheating of the solution (initial conductivity 100 - 800 microS/cm) during its treatment and thus the hydrogen peroxide production efficiency is quite high. The second part of this thesis was done at the Ghent University, Department of Applied Physics, Belgium. Here the DC discharge was created in gas bubbles (He, Ar, N2 or Air) flowing water solutions. NaH2PO4 . 2H2O solution (5 microS/cm, V= 750 ml) was used to hydrogen peroxide production studies, Direct Red 79 (20 mg/l) and Direct Blue 106 (20 mg/l, V= 750 ml) solutions were chosen for the organic dyes destruction study. The minimal concentration of the H2O2 was obtained when 10 mA current was applied, while the maximum concentration was observed at the current 30 mA. It leads to the conclusion that concentration of hydrogen peroxide increases with increasing applied current. The organic decomposition showed the same trend. The higher energy was applied, the more organic dye was destructed. The third part of this thesis took place at the Queen's University of Belfast, Centrum for Plasma Physics, UK using high frequency plasma scalpel (Arthrocare). It was found that the hydrogen peroxide concentration has reached the maximal value in solutions with a small addition of an alcohol (0.25 %). Four different treated liquid 0.15 M water solutions of BaCl2, Na2CO3, KCl and NaCl (V= 20 ml) were used. The initial conductivity of the samples was around 13 mS/cm. From the taken results it was obvious that the biggest difference between pH values was obtained in the solution with the additional of ethanol. The active particles generated by discharge were detected by spectra, mainly OH radicals which are understood as precursors to hydrogen peroxide. The main innovation was study of the influence of additional of organic compound on the plasma process. It was obtained that plasma still can be generated in such solution kind which can be considered as the first step to plasma created in the pure organic liquid medium. The last part of this work looked at atmospheric pressure microplasma jet interaction with the liquid phase and it was carried out at the Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, UK during host internship. As a liquid medium a gold (III) chloride trihydrate (HAuCl4.3H2O) aqueous solution with different initial conductivity was used. Interestingly, even a very low current (0.05 and 0.2 mA) generates stable plasma and produces hydrogen peroxide which can be understood as a very good result. Here, H2O2 behaviours as an oxidizing agent which converts gold precursors into gold nanoparticles.

Análise da energia utilizada por bisturi elétrico na ablação de tecido orgânico

Electrosurgery is a surgical technique that uses an electrosurgical device for cutting, drying (desiccation), and coagulation of organic tissue, thereby reducing the risk of bleeding. Electrosurgical device uses sparking phenomena for this purpose. This process causes heating of intracellular water and, consequently, the rupture of the cell in the organic tissue. Although the amount of energy delivered by the electrosurgical device is easy to know, little is known about the exactly amount of energy involved in the various phenomena of electrosurgical procedure, especially in cutting, where cells suffer ablation by vaporization Based on this was developed this research, which objective is to determine the energy required for the electrosurgical cutting through the electrical parameters involved and the energy used for the vaporization of water of organic tissue. The method developed was corted in three experiments, with a series of specific tests in each. It has been show that only about 10% of total energy is used for cutting, or specifically, for the vaporization of water of organic tissue. The rest of the energy is used in other processes that need more investigation to be understood.A eletrocirurgia é uma técnica cirúrgica que utiliza o bisturi elétrico para a realização do corte, dessecação e coagulação do tecido orgânico, diminuindo dessa forma os riscos de hemorragia. O bisturi elétrico usa o processo da faiscância para a realização do trabalho. Esse processo provoca, entre outras coisas, o aquecimento da água intracelular e, consequentemente, o rompimento da célula do tecido. Embora se saiba a quantidade de energia entregue pelo bisturi elétrico, pouco se sabe sobre as parcelas de energia envolvidas nos vários fenômenos do processo eletrocirúrgico, principalmente no corte, onde as células sofrem ablação por vaporização. Com base neste problema, foi desenvolvida esta pesquisa, que teve o objetivo de determinar a energia necessária para o corte eletrocirúrgico, através dos parâmetros elétricos envolvidos e da energia utilizada para a vaporização da água do tecido orgânico. O método desenvolvido foi testado em três experimentos, com várias séries de cortes específicos em cada. Demonstrou-se que da energia total que é entregue pelo bisturi, menos de 10% é utilizada para o corte, ou especificamente, para a vaporização da água do tecido. O restante da energia acaba sendo utilizada em outros processos que começarão a ser analisados em outros trabalhos

Caracterização da deflagração da descarga eletrocirúrgica

Electrosurgical spark is the phenomenon that rules the main effects of electrosurgery, cut and fulguration. Previous studies have shown evidences that electrosurgical sparkling generates important voltages and currents asymmetries, despite the presence of the dc protection capacitance at the patient circuit. Those asymmetries can lead to undesirable electrostimulation and dc burns. The present study has investigated the characteristics of the beginning of the spark, or the very moment of its breakdown, according to electrodes geometries, submilimetric gap distances, atmosphere temperature, pressure and humidity conditions, and electrodes materials. It was possible to notice a qualitative resemblance between the dc breakdown and the ac characteristics from previous studies. This association and peculiarities of the electrosurgical sparks and organic electrodes material influence are analyzed. Furthermore, characteristics such as alterations that can take place during sparkling processes due to changes in organic tissue when it gets dried are also presented and analyzed.A faísca eletrocirúrgica é o fenômeno que rege os principais efeitos da eletrocirurgia, o corte e a fulguração. Trabalhos anteriores forneceram evidências de que o processo da faiscância gera assimetrias importantes em corrente e tensão, a despeito da presença de capacitores nos circuitos do paciente. Tais assimetrias podem causar queimaduras eletrolíticas ou eletroestimulações indesejadas. Este trabalho investiga as características da deflagração da faísca, a quebra de rigidez dielétrica neste tipo de descarga elétrica, em espaços submilimétricos e em relação às geometrias, materiais e meio envolvidos na eletrocirurgia. Foi possível associar qualitativamente os valores dc aos valores ac de trabalhos anteriores. Esta associação e as peculiaridades da faísca eletrocirúrgica são discutidas aqui. Também são apresentadas as alterações que podem surgir nos processos de faiscância devido a alterações do tecido orgânico quando dessecado

Smart knives: controlled cutting schemes to enable advanced endoscopic surgery

With the backdrop of the rapidly developing research in Natural Orifice Transluminal Endoscopic Surgery (NOTES), analysis of the literature supported the view that inventing new, controlled tissue dissection methods for flexible endoscopic surgery may be necessary. The literature also confirmed that white space exists for research into and the development of new cutting tools. The strategy of “deconstructing dissection” proposed in this thesis may provide dissection control benefits, which may help address the unique manoeuvring challenges for tissue dissection at flexible endoscopy. This assertion was supported by investigating six embodiments of the strategy which provided varying degrees of enhanced tissue dissection control. Seven additional concepts employing the strategy which were not prototyped also were offered as potential solutions that eventually might contribute evidence in defence of the strategy. One concept for selective ablation — dye-mediated laser ablation — was explored in-depth by theoretical analysis, experimentation and computation. The ablation process was found to behave relatively similar to unmediated laser ablation, but also to depend on cyclic carbonisation for sustained ablation once the dye had disappeared. An Arrhenius model of carbonisation based on the pyrolysis and combustion of wood cellulose was used in a tissue ablation model, which produced reasonable results. Qualitative results from four methods for dye application and speculation on three methods for dye removal complete the framework by which dye-mediated laser ablation might deliver on the promise offered by “deconstructing dissection”. Overall, this work provided the “deconstructing dissection” strategic framework for controlled cutting schemes and offered plausible evidence that the strategy could work by investigating embodiments of the scheme. In particular, dye-mediated laser ablation can provide selective ablation of tissue, and a theoretical model for the method of operation was offered. However, some practical hurdles need to be overcome before it can be useful in a clinical setting