INTRODUCTION:

Biomedical electronics have a significant impact on society because of their applicability to the present medical industry. Traditionally, the subjects of biomedical electronics have been associated with instrumentation and signal processing, emphasizing the analog design and the sensors which are the core for all the conventional diagnosis systems^1,2. Nonetheless, recent years have seen a broader application of the electronics in biomedical frameworks consisting of digital, analog and power systems not only for diagnosing and monitoring but also for implant systems as well as treatment.

Furthermore, the advancements in industrial electronics have allowed the design of high-performance systems which have resulted in exploring different techniques for diagnosis and treatment that have not been used in traditional approaches of biomedical electronics^3,4,5,6. Electroporation is one such biomedical application to which electronics have been applied through which the permeability of the cells can be enhanced. It is an anomaly that takes place in the presence of a high electric field when a membrane is exposed to it⁷. Many of the biological and physical parameters affect the competence of electroporation. These parameters can be bifurcated as cell parameters that provide information about the condition of the cells, their surrounding and geometry, electric field parameters. In the applications of electroporation, the parameters of the electric field are generally controlled and adjusted to particular cell parameters and the electroporation objectives⁸. According to the electrical point of view, the cell plasma film can be an insulating sheet encompassed on the two sides by aqueous electrolytic mixtures. At the point when it is exposed to an adequately stable electric field, the layer will experience an electrical breakdown, making it porous to the particles which are generally not able to cross it. This process is known as electroporation. In contrast to solid insulators, wherein the electrical breakdown, for the most part, causes a change in the structure, the layer, with its lipids carrying on as a two-dimensional fluid, can immediately come back to its initial state (before breakdown). The duration of exposure of the external field determines the nature of the electroporation. If the external field is applied for a shorter duration then the electroporation is termed as reversible and if the duration is large then it is termed as irreversible electroporation⁹. Thus, it is assertion that electroporation can be either reversible or irreversible and irreversible electroporation leads to cell death. Whereas reversible electroporation can be further optimized for introducing large as well as small molecules, fusing the cells and inserting proteins in the cell membrane. Electroporation technique since its inception came up as a tool to be used in different regimes of medicine and biotechnology^10,11,12. Presently reversible type of electroporation is a well-established technique for bringing chemotherapeutic medications into tumor cells (electrochemotherapy) ^13,14. It additionally offers a strategy for gene therapy without being exposed to the hazards of viral vectors. Irreversible type of electroporation is used for ablation of tissues¹³ and microbial inactivation leading to conservation of food^15,16. The electric field used using the process of electroporation are very high but since it is being applied in the form of pulses it results in reduced power and increased energy efficiency⁹. The pulsed electric field is created between two electrodes by applying a high voltage pulse to one of the electrodes and another electrode at ground potential. Through this process, a wide range of pulsating voltages is generated, which can be used for specific applications. Furthermore, the magnitude of generated pulses varies from 1kV to 100kV, with timing variations ranging from milliseconds to nanoseconds. In general, it can be inferred that the higher the voltage requirement, the shorter will be the time period. Hence to carry out the process of electroporation, the generation of these pulses with accurate pulse width, amplitude, and frequency is required. This study offers the comparative analysis of pulse generation methods being used for the process of electroporation.

Electroporator classifications:

In the process of electroporation, the reproducibility and viability depend on the accurate reproduction of the electroporation signal which is applied. Therefore, the electroporation depends on the variation of electric field magnitude in nearby regions, in many cases, the output voltage can be controlled. The number, duration, amplitude, commutation sequence and repetition frequency of the pulse, characterizes the electroporation signal. In order to produce electroporation pulses, it requires a high voltage so that it can be controlled in a right way. These high voltage-controlled pulses are then applied to the cell under consideration. So, it is evident that there can be a variety of pulses which can be generated as per the specific applications but there are two things that are common to all the pulses. Firstly, that voltages of all the pulses are in the range of 1-100kV and secondly the pulse duration ranges from millisecond to nanosecond¹⁷. It can also be said that for high voltages pulses the duration of the pulse is shorter. Thus, the scope of the pulses that can be used are rectangular, exponential and a combination of wide and narrow pulses, as illustrated in Fig. 1. The high voltage pulses can either be bipolar or monopolar as illustrated in Fig. 1. For the applications of air and water disinfection rectangular pulses are applied during the combination of the wide and narrow pulses which have been proposed recently^18,19,20 are preferred for the applications of sterilizing food, without any alterations in the freshness and the nutritional value of the food^21,22.

Figure 1: Different type of electroporator waveforms (reproduced from Elgenedy et al., 2017)²³

Exponential pulses:

The exponential pulses as shown in Figure 2. are generated with the help of an inexpensive simple capacitor discharge circuit. The maximum amplitude for the pulse is set by a preset voltage to which the capacitor (C) is charged. The C will be discharged through a load (Z_L). Thus the time in which the pulse is constant is given by τ = C |Z_L|. At the time of delivering the pulses, the impedance of the load (biological) decreases and also varies among different samples, in turn, varying τ²⁴. To prevent this variation, the load is connected in parallel to an in-built resistor R due to which the limit of the time constant during the pulse decreases. As compare to the other circuits the capacitor discharge circuits are the easiest and the least expensive which can easily use for electroporation circuits in terms of per unit pulse energy consumption. However, the development of the circuit comes with different challenges when is high voltage or current are needed. The output voltage reaches several kiloamperes or few megavolts when the spark gaps are utilized as switches. The fundamental issue is concurrent switching at the spark gaps. A perfect technique to adopt for doing this process is by utilizing a UV laser. The repetition frequency of the pulse is generally under 100 Hz because of the long-time required for charging. The DNA can be inserted into the cells (gene transfection) through exponential pulses. The insertion of DNA requires a specific high voltage pulse pattern where in high voltage is used for the permeabilization of the cell and a low voltage is required for movement of the DNA electrically²⁵. The pattern is not general rather the low voltage component is used more in the case of irreversible electroporation since it greatly effects the viability of the cell²⁶. Cell viability is of much lesser concern in gene transfection of microscopic organisms. However, it becomes an important concern when we transfect a very important cell and for that we use a square wave pulse frequently²⁷. The ideal waveform is defined by the equation

y = e^-a×n

Here a is the amplitude of desired wave and the n is number of pulses.

Figure 2: Exponential pulse for electroporator

Square Pulses:

The square pulses (figure 3) are known as the rise time of the pulse denoted by tr and fall time denoted as t_F. In the case of milli and microsecond pulses, the variations in t_F and t_r have a negligible effect on the process of electroporation. But in the case of pico and nanosecond square pulses, the electroporation impacts the organelles. The switching circuit in an high voltage (HV) power supply generates Milli and microsecond square wave pulses²⁸. The generators of square pulse produce a single preset voltage. Since it is typically necessitated that each pulse has an identical amplitude, the next pulse can be delivered once the capacitor is revived to the preset voltage. Systems used to create pico and nano square pulses contrast essentially from those used to create Milli and microsecond pulses, claiming switching components of HV have turn-off times which are excessively long to structure pico and nanosecond pulses. These square-pulse generators are utilized practically for all applications of electroporation, not just in light of its cost and simplicity, also due to the fact that they empower reproducibility and great control of the electrical parameters which are relevant. Nonetheless, the load must be changed in accordance with the pulse-forming system impedance in order to avoid the delivery of variable amplitude to the reflections of the load and pulse. The biological load impedance can be brought down by connecting extra resistance in parallel, and the transmission line impedance can be brought down by including indistinguishable transmission lines in parallel. The waveforms are defined by following equation

A = offset + ɑ(2πft / d)

Here offset is the initial level of the pulse, a is the maximum amplitude of the pulses f is the frequency of the pulses and is equal to t is the pulse period, d is the duty cycle

Figure 3: Square pulse for electroporator

As of now we have discussed about the different pulses that can be used for different applications of electroporation in medicine and biotechnology. Now we will be discussing about the millisecond and nanosecond pulse generators which can be used for generate the above discussed pulses.

Millisecond Pulse Generators (MPG):

Millisecond pulse generator can be used to remove tissues using irreversible electroporation (IRE). The Same is reported by Edd et. al. (2006)²⁹. In this paper is based on prior hypothetical work and shows that IRE can be a powerful technique for removal of tissue non thermally without the use of any medicines^30,31. The authors performed a experiments on rat liver tissue using a 1000 V/cm square wave pulse of 18ms duration to find out the effectiveness of IRE pulse to remove tissues in effective and controlled manner. It can be concluded that IRE can be used to remove tissues thermally without significant damage to the surrounding regions containing healthy tissues. To generate high voltage (HV) pulses repetitively for electroporation Wu et al. (2007)³² modified the conventional Marx generator to develop a repetitive HV pulsed generator. The Marx modulator utilizes high voltage IGBT switches and diodes connected in series. Besides, it is sensible that IGBT drivers use a technique for self-provided control. Experimental outcomes of 20 phases producing beats with 60 kV, 20-100 μs and 50~500 Hz validated the system performance. The experimental outcomes of both plasmas, as well as a resistive load, showed that it can produce repetitive HV rectangular pulses with low voltage control source. The rate of transfection for different electroporation parameters were studied by Rodamporn et al. (2007)³³. The author designed and tested a programmable electroporator to study the effects of electric field and pulse length on electroporation. Electric fields of 100 to 1000V/cm were generated using the commercial electroporation cuvette. The model was assessed with propidium dye and Hela cells for evaluating the rate of transfection for various conditions of electroporation. The results showed that the system accomplished a transfection efficiency of 48.74% at 600V/cm for 10 ms long pulses. The author Pokryvailo et al. (2010)³⁴developed a small size, high efficiency and a low-cost HV power supply (HVPS) to be used for millisecond pulse generation. This technique includes energy-dosing inverters which run at 50kHz with an efficiency of 97.5% across all operating conditions. The output voltage of the inverters is phase-shifted which results in a low ripple of 1%. Modular construction permits the simple fitting of HVPS for explicit requirements. Attributable to high effectiveness, small size is accomplished without water cooling. Controls give standard working highlights and progressive digital processing capacities, alongside the ease of obliging application-explicit necessities. It is demonstrated that the ripple factor and the number of modules which are being squared are inversely proportional to each other. The experimental voltage and current waveforms show that lossless switching for loads that fluctuate broadly in the full scope of the line input voltages and agree reasonably with circuit simulations. For a full load efficiency of 95% is achieved. Pulsed electric field repetitive in nature was applied to germ cell membrane to disinfect it by the author Elserougi et al. (2016)³⁵. Through this technique, irreversible electroporation with the destruction of the cells is accomplished. They developed a bipolar pulse generator with a half-bridge submodule by sequentially charging the capacitors. The pulse generator provided a pulsed output of high voltage with the use of a comparatively low voltage rated IGBT, which avoided the complexity of semiconductor devices that are stacked. The generator produced pulses of 0.2ms with a repetition rate of 200 bipolar pulses per second. Recently the author Elserougi et al. (2017)³⁶proposed a converter for high voltage pulse generation. The converter proposed is based on buck-boost (BB) technique and it is fed by using a low voltage supply. It is capable of generating both bipolar and unipolar pulses by operating the converter with outputs connected parallel or series utilizing the dc input source. The converters are operated in Discontinuous Conduction Mode (DCM) resulting in improved efficiency of the system since the circuit operated only when required else it will be switched to idle mode. The concept is validated through simulations and experiments. The pulse width for both unipolar and bipolar pulses of magnitude 700V and 350V respectively was 0.5ms.

Nano-second Pulse Generators (NPG):

A comparison of the micro and nano second pulse generators indicates that the pulse duration in case of nano second pulses are lower as compared to the rise time of millisecond pulses. So, it is quite evident that we cannot use the same switches to generate nanosecond pulses which were earlier used to generate millisecond pulses. Additionally, the amplitude of nanosecond pulses are in the range of kV which is much higher than the specifications of the switches used in the case of millisecond pulse generator or electroporator. For averting the undesirable pulse reflections which are a result of mismatched impedance between the load and generator, the circuits of nanosecond pulses require more careful design. These issues have been rectified with the use of blumlein and diode opening switch generators which are at present the two fundamental nanosecond high-field pulse generating circuits (figure 4) for electroporation³⁷.

Modelling and exploratory investigations have demonstrated that pulsed electric fields in the duration of nanoseconds and mV/ meter of the amplitude influence structures of the sub cells, however, do not result in large pores being formed in the external membrane. Kolb et al., (2006)³⁸ described the design, operation and the required diagnostics for the pulsed power sources. They developed two kinds of pulsed generators which were based on the principle of Blumlein line. One system is developed for treating the cells in the cuvette maintaining the volume in the range of 0.1 to 0.8ml. The pulses applied to the cuvette have an amplitude of 40kV with a rise time of 1ns and a duration of 10ns. The other system will allow real-time observation of each cell which is under the microscope. It generated pulses with a duration of 10 to 300ns and a rise time of 3.5 ns and 1kV voltage amplitude. From the outcomes, it can be inferred that that nanosecond pulses can prorate the atomic film without harming the cell membrane, while the pulses of longer duration with the same energy can damage the cell membrane. The author Kim et al. (2003)³⁹ developed an HV bipolar pulse generator with the help of a push-pull inverter. The designed system comprised of a DC link, thyristor rectifier, high voltage transformer, variable capacitor, push-pull resonant inverter, high voltage IGBT, and secondary capacitor. This system produced an HV bipolar sinusoidal waveform by utilizing the resonance among the transformer and secondary capacitor. The generated pulses had a pulse width of 400 - 1200ns, rise and fall times of 250ns and 500 ns respectively. However, the stacked IGBT and diodes required the dynamic and static voltage sharing. This system was better with respect to flexibility, cost, and efficiency when compared to the circuits based on nonlinear transmission lines. Novel and economical NPG was developed by Chaney et al. (2004)⁴⁰. The NPG consists of a single MOSFET buffer, Schmitt trigger, and IC driver circuit. Fast rise time was produced by Schmitt trigger. For a matched load of 50Ω, the pulsed generated repetitive, well-defined pulses of high voltage which are free from the issues of overshoot and ringing. The pulse width can be adjusted from 75 ns to 10 ms. These pulses have a fall time of a few nanoseconds for the negative wave and the repetition period was 1.5s. Electric fields of 4–1 kV/cm can be generated with the help of 1 to 4 mm standard cuvette. The pulse width can further be reduced using a complex driver circuit, this, however, will increase the complexity of the circuit. A unipolar NPG was developed by Shao et al. (2010)⁴¹ with the help of single-stage magnetic compression and resonant charging circuits to which the magnetic and IGBT switches respectively are the keys. The pulsed power generator consists of two parts the low and high voltage units. The later utilized for increasing the voltage of the pulses and compress the pulse width while the former accomplishes the resonant charging. This pulse generator circuit can produce repetitive pulses along with a voltage up to 30kV for 70ns for a resistive load of 300Ω. The trigger pulse width or the input ac voltage can be varied to adjust the output pulse voltage. From the results, it could be inferred that the pulse generator met the requirements of the dielectric barrier discharge (DBD) load and can be utilized in experimentally investigating the nanosecond pulse DBD. But the circuit does not have the capability for further reduction of the pulse width for the output voltage of the load. Later on, in the same year Merla et al. (2010)⁴²developed a numerical and experimental model of a nanosecond 10Ω pulse generator that utilized the technology of microstrip and photoconductive switches which are laser triggered. The load for the generator is an electroporation cuvette. For the complete setup comprising of the cuvette and generator SPICE and FDTD models are developed. SPICE analysis and the FDTD simulations are compared for performing the numerical characterization. A prototype with a voltage sensor with wideband frequency is used for experimental characterization. The voltage intensities between the experimental and numerical measurements were in good agreement with each other. The data obtained numerically predicted favourable behaviour of the device with respect to the generation of variable pulse shapes, the intensity of voltage and fall and rise times. Sub nanosecond electric pulses was generated by El Amari et al. (2010)⁴³. The author developed a pulse generator which can generate picosecond, as well as monocycle nanosecond pulses with unbalanced or balanced negative and positive segments. Bipolar pulses with frequency customization of 100 MHz – 2GHz is produced. In the year 2011 the author Jiang et al. (2011)⁴⁴ developed a concise repetitive NPG which was based on the transmission line transformer (TLT) for generations of nonthermal plasma. The magnetic cores present around the coaxial cable are designed in a way so as to ensure a high voltage gain. The optimization of the TLT layout has resulted in a more compact generator. From the experimental results, it was observed that the generated pulses had an amplitude of 30kV, a pulse width of 100 ns and a rise time of 25 ns. In the quest for NPG which is cable of varying the amplitude, polarity, repetition rate and duration of pulses Romeo et al. (2013)⁴⁵in the year 2013 developed a microstrip transmission line which had the conducting strip in meander-shape with a high voltage ultra-fast switch. This system was appropriate for the application of nanosecond pulses in which the amplitude, polarity, repetition rate and duration of pulses could be varied. The developed circuits generated pulses with a voltage level of 1.5 to 5V, a duration of 10ns and 10s and a repetition rate of 100MHz. Even though this technique provided satisfactory results, the output pulses across the loads experience residual oscillations which can be attributed to non-ideal matching amid the transmission lines and the load. In addition, connections of the interface with the microstrip-lines are especially significant and must be handled carefully so as to lessen the distortions in the pulse and losses due to efficiency. To sterilize microorganism in a better and efficient way Lan et al. (2015)⁴⁶ designed an HV NPG for generating square pulses which are bipolar in nature. The primary part of this circuit is the non-trivial combination of the H bridge and half-bridge Marx generator in series connected to a DSP control unit which has the capability to alter the frequencies, polarities, pulse widths, voltages, and furthermore endure different loads. The system generated pulses of 160 ms pulse width. The stability and reliability of the NPG with respect to the safety of operation and different load conditions are validated through experimental analysis. Moreover, from the results, it can be inferred that the key parameters dependent on the developed NPG can be effectively altered including the frequencies, polarities, voltages, and pulse widths. In the year Mi et al. (2016)⁴⁷ developed Blumlein stripline as a unit that forms and propagates square waves. The multistage parallel, series Blumlein stripline with adjusted pulse width is utilized for a small space so that it is able to adapt various impedance loads of biological experiments. As a result, the stripline has a wide range of characteristic impedance making it easy to design based on the requirement. The traditional coaxial line can be replaced by the stripline for the effective reduction in the volume. The ability of the system to repeat the regulation and the operating frequency is enhanced by introducing an equalization circuit. The pulse is generated with a rise time of 10-20ns. However, the load distribution and the stray parameters affect the generated pulses which can be overcome by optimizing the circuit which will also improve the accuracy. Later on, the author Mi et al., (2016)⁴⁸ designed an HV NPG by combining the unbalanced Blumlein Type multilayer microstrip transmission line and him solid-state switches. This study emphasized the significance of reduced NPG for biomedical applications. The analysis of voltage wave propagation is utilized to describe the system principle. Depending on this analysis the technique for generating the pulse widths and controlling the timing of the switches is interpreted. They developed a prototype of the system to evaluate its performance. The NPG generated rectangular pulses for a load resistance of 50Ω with an amplitude of 0–2 kV, 20ns rise time and 50 to 100 ns pulse width. When a 500Ω resistor was used instead of the 50Ω then NPG output was two times the charging voltage which has been applied. In the year 2017 Butkus et al. (2017)⁴⁹presented a SPICE model that gives square pulses of 100-900ns and voltage ranges from 0KV to 3KV. The circuit is divided into four parts to perform different operations. The switching part is done with the help of a microprocessor, high-frequency pulse is produced by MOSFET. In the year 2018 Pirc et al. (2018)⁵⁰ designed and developed an electroporator circuit for generating nanosecond pulses. To achieve the pulse in ns the appropriate solutions is diode opening switch and network. SiC is used as an RF MOSFET in the circuit for switching due to its property like low leakage current, better radiation hardness, and high operating points. Similarly, Ryan et al., (2018)⁵¹ developed a pulse generator which is capable of producing nanosecond pulses (NPG). Test results of the generator demonstrate that this NPG can be very helpful in investigating the biophysical instrument of cell reactions to extreme and ultrashort pulsed electric fields, and may serve to adjust explicit impacts for biomedical application in an exceptionally controlled manner. On the same year Mi et al., (2018)⁵²developed a pulse generator based on the transmission-line transformer. The pulse generator can generate bipolar, negative and positive pulses. Each module of the generator uses solid-state switches for controlling the BPFL. Regulation of the control signal time aids the generation of nanosecond pulses with a high rate of repetition by the BPFL. This proposed circuit operation is verified through simulation and experimental evaluations. Finally, a prototype of four stages was developed which generated pulses of 0-10 kV amplitude and 30ns width, adjustable polarity, and up to 200 kHz repetition rate. In the year 2019 Butkus, et al., (2019)⁵³presented a numerical study of pulses and how their amplitude, magnitude and shape affect the number of pores created in electroporation. Different shapes of pulses are numerically verified like rectangular, exponential, triangular pulses. It is observed that among all the pulses only rectangular pulses give the most effective results also have enhanced control on the pulse energy. The detailed comparison of millisecond and nanosecond pulse generator discussed above is summarized in the table -1.

Table I: Comparative study of different type of electroporators.

Author and Year	Technology/Topology used in circuit	Summary
Author and Year	Technology/Topology used in circuit	Components Used	Type of pulses	Voltage	Pulse Width
(Kolb et al., 2006)³⁸	The pulse generator is based on transmission line model	MOSFETS, Capacitors, pushbuttons used for spark gap, power charging system	Unipolar rectangular pulses	1kV	10-300 ns
(Wu et al., 2007)³²	The pulse generator is based on the Marx generator.	IGBT Gate driver, Capacitor, self-supplied power.	Rectangular pulses	60 kV	20-100 μs
(El Amari et al., 2010)⁴³	The pulse generator is based on Optoelectronic Switching	Photoconductive semi- conductor switches (PCSSs), REGP02-20E diodes	Bipolar pulses	20 kV	15ns
(Jiang et al., 2011)⁴⁴	The pulse generator is based on TLT	IGBT, Diode, Inductors, Capacitor, DBD (Dielectric barrier discharge)	Bipolar pulses	30kV	25ns
Kranjc et al.³⁷	Blumlein generator and diode opening switch (DOP)	Voltage power supply, a charging resistor, two transmission lines and a switch, MOSFET APT37M100L.	Bipolar pulses	100 to 1000V	50 ns
Cronje et al.⁵⁴	Cascaded multilevel inverter topology	FPGA, RF MOSFETs (DE375-102N12A) HCPL-2400 optocoupler, UCC37321 gate driver, Damping resistors.	Bipolar pulses	800V	125kHz to 1MHz
(Lan et al., 2015)⁴⁶	The pulse generator is based on half-bridge Marx generator and H- bridge	Marx generator, H bridge, Capacitor, diode, IGBT	Bipolar Square Pulses	7kV	160ns
Bullmann et al.⁵⁵	Capacitors are used to perform a monostable operation	NE555 Timer, LM317 current limiter, FTR-K1CK012W/ D81A3108X7 latching relay	Square wave pulses	27V, 36V or 47V	20 to 200 ms with an accuracy of ~10%
Shagoshtasbi et al.⁵⁶	IoT (arduino based)	Arduino DUE, Analog-to-Digital Converter (ADC)/ Digital-to-Analog Converter (DAC), Bluetooth, LCD	Rectangular electric pulses	Amplitudes 1-4 V	Adjustable, durations 2-8 ms
Novickij et al.⁵⁷	IGBT switching	IXEL40N400 IGBT, PNP transistor BJT	Square wave Pulses	Generated up to 4 kV	5 μs–10 ms
Novickij et al.⁵⁰	IGBT, MOSFET switching topology	Half-bridge drivers ADUM4223CRWZ, MOSFETs C2M0080120D, Microcontroller	Square wave Pulses	3kV, 60 A	100 ns to 1 ms
(Elserougi et al., 2016)³⁵	Two groups of half-bridge submodules	IGBTs, capacitor, half bridges, TI-TMS320F28335 DSP	Bipolar Rectangular Pulses	20kV	20 µs
(Mi et al., 2016)⁴⁸	The pulse generator is based on Blumlein-type transmission line	MOSFETs, IXRFD630 driver, RCD buffer, unbalanced Blumlein-type multilayered microstrip transmission line	Square Pulses	2kV	50-100 ns
Butkus et. al.⁵¹	Controlled crowbar circuit using MOSFET	Microprocessor, galvanically isolated MOSFETs and drivers ADUM4223, C2M0080120D MOSFET	Square Wave Pulses	3 kV	100 ns up to 1 ms
Moonesan et al.²²	Microcontroller	Microcontrollers MOSFET K119, three-stage capacitive Multiplier circuit, H bridge circuit.	Eight Square Wave Pulses	1300V/cm amplitude and 5 KHz frequency	100 μs
Pirc et al.⁵²	Cascaded multilevel integrated topology	SiC MOSFETs for switching	Square Wave Pulses	More than 6kV	~ 8ns
(Ryan et al., 2018)⁵⁸	The pulse generator is based on fundamental nanosecond module	MOSFET, Capacitor, Two-switch Blumlein pulse generator, linear transformer driver (LTD) generator, Marx generator	Rectangular Pulses	5kV	80ns
(Mi et al., 2018)⁵⁹	The pulse generator is based on Blumlein pulse-forming line and a transmission-li ne transformer	H-bridge, Transmission-line transformers (TLTs), driver (IXRFD630), HV DC source, MOSFETs	Bipolar pulses	10kV	30ns
Butkus et al.⁵³	Controlled Crowbar circuit	ADUM4223 gate driver, SiC MOSFETs, RC snubber circuits	Square Wave pulses	3kV	100-900ns sub-microsecond

CONCLUSION:

The process of electroporation of its types (irreversible and reversible) and electrical breakdown of the external layer of biological cells are investigated for various biological and medicinal applications. This paper discusses the number of applications of different types of electroporator. It is analysed that the even though electroporation and to some extent electrofusion depend on the technology of pulsed power, the circuits still seek modifications. Hence, the community of pulsed power needs to be actively involved in developing the pulsed power generators for bioelectric in the early years. However, there are some exceptions where the studies focussed on using the electric field for decontaminating the food from bacteria. The recent decades, however, is observing the development of various models of pulse generators for the electroporation applications. This paper compares different models presented in literature. This paper majorly compares different type of pulses generated by different models. The generator generates ideal and bipolar rectangular pulses, exponential pulses and square pulses. It is inferred that regardless of the advancements in various biological and medical methods based on electroporation, the methods of electroporator generation are still evolving. This significantly holds good for the various applications of electroporation. The requirement to design and develop simple, low impedance, reliable, pulse generators which generate pulses in the range of kilovolts for nanosecond durations is a challenging task. This paper offers the required analysis to address the challenges for generation of electroporator.

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Received on 06.04.2020 Modified on 10.07.2020

Research J. Pharm. and Tech. 2021; 14(5):2843-2851.

DOI: 10.52711/0974-360X.2021.00501