Effect Of Pulsed Electric Fields Research Articles

Enhancement of Polyphenols Recovery from Rosa canina, Calendula officinalis and Castanea sativa Using Pulsed Electric Field

The current study evaluates the Pulsed Electric Field (PEF) technique for the extraction of polyphenols from the plants Rosa canina, Calendulaofficinalis and Castanea sativa. These plants are traditionally used both for the preparation of therapeutic decoctions and the aromatization of beverages (alcoholic or not). Pulses of 10 μs duration were used to apply electric field intensities ranging from 1.2 to 2.0 kV cm−1. The period of the phenomenon was set to 1 ms, with a total extraction time of 20 min. The total polyphenol content as well as the identified polyphenolic compounds of the extracts were determined for monitoring and evaluation. To estimate the PEF effect, control extracts were prepared using the same process as PEF extracts but without the application of electric field. For all the three plant materials studied, the PEF technique appeared to be successful in increasing polyphenols extraction. The application of a moderate to high electric field, up to 1.4 kV cm−1, resulted in increased total and individual polyphenols recovery, reaching 63.79% and 84%, respectively, in the case of Rosa canina fruits.

Apple Juice Preservation Using Combined Nonthermal Processing and Antimicrobial Packaging

This study was conducted to investigate the effectiveness of pulsed electric fields (PEFs), pulsed UV light (PL), and antimicrobial packaging (AP), either individually or combined, for inactivating bacteria and maintaining the quality of fruit juices. Apple juice samples were inoculated with Escherichia coli K-12 or native molds and yeasts (M&Y), treated with bench-scale PEF and/or PL processing systems, and stored in glass jars with antimicrobial caps containing 10 μL of carvacrol. The reductions in microbial populations and the physicochemical properties of juice samples were determined after treatments and during storage at 10°C. The treatments were PL (5 to 50 s at 1.04 J/cm2/s), PEF (19, 23, and 30 kV/cm), PEF followed by PL (PEF+PL), PL followed by PEF (PL+PEF), and PEF+PL+AP. PEF treatments at 19 to 30 kV/cm (PEF19, PEF23, and PEF30) resulted in 2.0-, 2.6-, and 4.0-log reductions of E. coli, respectively, and PL treatments for 10 to 50 s (PL10, PL20, PL30, PL40, and PL50) resulted in 0.45-, 0.67-, 0.76-, 2.3-, and 4.0-log reductions, respectively. No significant differences (P > 0.05) were found between the combined PL20+PEF19 and PEF19+PL20 treatments; both treatments reduced E. coli K-12 populations to nondetectable levels (>5-log reductions) after 7 days. Both PEF+PL and PEF+PL+AP treatments achieved >5-log reductions of M&Y; however, juice samples subjected to PEF+PL+AP treatment had lower M&Y counts (2.9 log units) than did samples subjected to PEF+PL treatment (3.9 log units) after 7 days. No significant differences (P > 0.05) in pH, acidity, and total soluble solids were found among all samples after treatments. Increased PL treatment times reduced color a* and b* values, total phenolics, and carotenoids. This study provides information valuable to juice processors for consideration and design of nonthermal pasteurization of juice products.

Simulation of the Influence of Temperature on the Dynamic Process of Electroporation Based on Finite Element Analysis

Pulsed electric fields (PEFs) had the potential to be a new pasteurization technology due to its advantages of energy-saving, high efficiency, and less influence on food quality based on the electroporation effect of PEF on microorganisms. At the same time, temperature played a significant role in the electroporation process. We established a two-membrane dielectric model that coupled temperature and PEF to study the influence of temperature on the dynamic process of electroporation. In this model, we considered both the effect of Joule heat on temperature generated by PEF and the effect of temperature on the conductivity of suspension, cytoplasm, nucleus, the characteristic voltage of electroporation, and molecules transport. The simulation results showed that under the higher ambient temperature, the transmembrane voltage of the cell membrane after electroporation could be stabilized at a higher value, the maximum value of membrane conductivity and pore density on the cell membrane was higher. The relationship between pore radius and temperature was simulated. What is more, temperature facilitated molecules transport, which intensified the destruction of cell homeostasis.

Differential effects of nanosecond pulsed electric fields on cells representing progressive ovarian cancer

Nanosecond pulsed electric fields (nsPEFs) may induce differential effects on tumor cells from different disease stages and could be suitable for treating tumors by preferentially targeting the late-stage/highly aggressive tumor cells. In this study, we investigated the nsPEF responses of mouse ovarian surface epithelial (MOSE) cells representing progressive ovarian cancer from benign to malignant stages and highly aggressive tumor-initiating-like cells. We established the cell-seeded 3D collagen scaffolds cultured with or without Nocodazole (eliminating the influence of cell proliferation on ablation outcome) to observe the ablation effects at 3 h and 24 h after treatment and compared the corresponding thresholds obtained by numerically calculated electric field distribution. The results showed that nsPEFs induced larger ablation areas with lower thresholds as the cell progress from benign, malignant to a highly aggressive phenotype. This differential effect was not affected by the different doubling times of the cells, as apparent by similar ablation induction after a synergistic treatment of nsPEFs and Nocodazole. The result suggests that nsPEFs could induce preferential ablation effects on highly aggressive and malignant ovarian cancer cells than their benign counterparts. This study provides an experimental basis for the research on killing malignant tumor cells via electrical treatments and may have clinical implications for treating tumors and preventing tumor recurrence after treatment.

Selected Quality Parameters of Air-Dried Apples Pretreated by High Pressure, Ultrasounds and Pulsed Electric Field-A Comparison Study.

The aim of this work was to compare selected physicochemical properties of air dried ‘Golden Delicious’ apples, pretreated either by high-pressure processing (HPP), ultrasound (US) or pulsed electric field (PEF). Following parameters of pretreatment were used: HPP–400 MPa for 15 min, US–21 kHz, 180 W for 45 min, PEF–1 kV/cm, 3.5 kJ/kg. The quality of materials was evaluated by their rehydration properties, hygroscopicity, color and total phenolic content. To compare the effectiveness of the utilized methods, determined properties were expressed as relative comparison values against the reference sample obtained without any pretreatment in the same conditions. The performed research demonstrated that properties can be shaped by the application of proper pretreatment methods. For instance, PEF was shown to be the best method for improving water uptake during rehydration, whereas HPP was the most effective in decreasing hygroscopic properties in comparison with untreated dried apples. Among the investigated methods, HPP resulted in the deepest browning and thus total color difference, while the effects of US and PEF were comparable. For all pretreated dried apples, the total phenolic content was lower when compared with reference material, though the smallest drop was found in sonicated samples.

Thermoelectric Performance Enhancement of Film by Pulse Electric Field and Multi-Nanocomposite Strategy.

Thermoelectric (TE) film has wide potential application in low-grade waste heat recovery and TE generation due to its quick response and multifunctional integration. Multi-nanocomposite is a promising method to solve the difficulty of maintaining temperature difference and achieving a high figure of merit ZT. However, the depletion layer induced by the multi-nanocomposite typically degrades performance. This study presents a simple and convenient method to solve this problem by pulse electric field (PEF). Prototypical TE Bi2 Te3 is selected as the objective film. The strong current density effect of PEF removes the depletion layer among carbon nanotubes (CNT) and Bi2 Te3 grains. Thus, the CNT nanocomposite with PEF treatment breaks the trade-off between electrical conductivity and Seebeck coefficient, achieving a power factor of 4400 µW m-1 K-2 which stabilizes after annealing effect to 2920 µW m-1 K-2 , a record for Bi2 Te3 films. Simultaneously, the self-assembled porosity decreases thermal conductivity via phonon scattering while still maintaining a high electrical conductivity of 3130 S cm-1 . Thus, the porosity helps maintain the temperature difference and thereby enables a sharp increase in output power. These results indicate that the combination of PEF and multi-nanocomposite is a new method to enhance TE performance, which would have a potential application in the commercial field.

Effects of microsecond pulsed electric field (μsPEF) and modular micro reaction system (MMRS) treatments on whey protein aggregation

Electric field (EF) processing has been suggested to be a promising technology in the valorisation of side-streams, such as whey, by enhancing the functionality of biomacromolecules. Shifting from batch to continuous processes and utilising more industry-relevant matrices are of great interest, yet studies thereof are lacking. A continuous plate–plate microsecond pulsed electric field (μsPEF) setup was optimised and whey protein concentrate (10%, w/w) was treated at 3 kV cm−1, 10 μs, 40–50 Hz. A diffuser inlet/outlet improved the process stability considerably. Average outlet temperatures between 64.1 °C and 73.2 °C were investigated and aggregate formation between 0.04 μm and 2000 μm was quantified. μsPEF-triggered particles were compared with those obtained in thermal treatments, conducted in a modular micro reaction system (MMRS) with similar temperature and residence times. A comparison of the Sauter mean diameter revealed that in the given EF process window, mainly thermal effects were responsible for aggregation shifts.

B-PO04-124 EFFECTS OF PULSED ELECTRIC FIELDS ON THE CORONARY VASCULATURE IN SWINE

Previous animal studies suggest a lack of significant injury to the vasculature following pulsed electric field (PEF) ablation. We sought to assess the effects of PEF on the coronary arteries in swine. We performed PEF ablations in pigs pretreated with dual antiplatelet and antiarrhythmic therapy. PEF was intracoronary using MapiT catheters (Biotronik, Berlin, Germany) or peri-coronary after epicardial access using EPT catheters (Boston Scientific, MA). PEF pulse duration was microsecond (Nanoknife 3.0, Angio Dynamics, NY) or nanosecond (CellFX, Pulse Biosciences, CA). We performed 39 intracoronary ablations in 10 pigs and 20 epicardial ablations in 4 pigs. PEF was delivered at an energy level of 23 (quartile range [QR 10-64]) J with 100 microsecond pulses in 10 ablations and 300 nanosecond pulses in 49 ablations. We observed reversible coronary spasm in 15 of 39 intracoronary ablations and 9 of 20 epicardial ablations. At the end study at 17 (QR 0-35) days, angiographic stenosis was seen with 17 of 39 intracoronary ablations and 0 of 20 epicardial ablations. Gross pathology lesions were observed in 27 (47%) lesions. Histopathology was performed for 13 lesions. In 10 of 13 lesions ablative changes were seen in the ventricular myocardium with median maximal diameter 14 (QR 5-19) mm and maximal lesion area 40 (QR 5-118) mm2. Coronary injury on pathology was seen in 2 of 4 intracoronary ablations and 0 of 9 epicardial ablations (Figure 1). In the swine model reversible coronary spasm was seen with both intracoronary and peri-coronary PEF. However, angiographic or histopathologic stenosis at the end study was observed only with intracoronary PEF.

Effect of Pulsed Electric Fields (PEF) on Extraction Yield and Stability of Oil Obtained from Dry Pecan Nuts (Carya illinoinensis (Wangenh. K. Koch)).

Pulsed electric fields (PEF) have been reported to increase the total oil extraction yield (OEYTOTAL) of fresh pecan nuts maintaining oil characteristics and increasing phenolic compounds in the remaining by-product. However, there is no information regarding the PEF effect on dry pecan nuts. Dry kernels were pretreated at three specific energy inputs (0.8, 7.8 and 15.0 kJ/kg) and compared against untreated kernels and kernels soaked at 3, 20 and 35 min. OEYTOTAL, kernels microstructure, oil stability (acidity, antioxidant capacity (AC), oil stability index, phytosterols and lipoxygenase activity), along with by-products phenolic compounds (total phenolics (TP), condensed tannins (CT)) and AC were evaluated. Untreated kernels yielded 88.7 ± 3.0%, whereas OEYTOTAL of soaked and PEF-treated kernels were 76.5–83.0 and 79.8–85.0%, respectively. Kernels microstructural analysis evidenced that the 0.8 kJ/kg pretreatment induced oleosomes fusion, while no differences were observed in the stability of extracted oils. PEF applied at 0.8 kJ/kg also increased by-products CT by 27.0–43.5% and AC by 21.8–24.3% compared to soaked and untreated kernels. These results showed that PEF does not improve OEYTOTAL when it is applied to dry pecan nuts, demonstrating that kernelsʹ moisture, oil content and microstructure play an important role in the effectiveness of PEF.

Recent Advances toward the Application of Non-Thermal Technologies in Food Processing: An Insight on the Bioaccessibility of Health-Related Constituents in Plant-Based Products.

Fruits and vegetables are rich sources of bioactive compounds and micronutrients. Some of the most abundant are phenols and carotenoids, whose consumption contributes to preventing the occurrence of degenerative diseases. Recent research has shown the potential of non-thermal processing technologies, especially pulsed electric fields (PEF), ultrasounds (US), and high pressure processing (HPP), to trigger the accumulation of bioactive compounds through the induction of a plant stress response. Furthermore, these technologies together with high pressure homogenization (HPH) also cause microstructural changes in both vegetable tissues and plant-based beverages. These modifications could enhance carotenoids, phenolic compounds, vitamins and minerals extractability, and/or bioaccessibility, which is essential to exert their positive effects on health. Nevertheless, information explaining bioaccessibility changes after non-thermal technologies is limited. Therefore, further research on food processing strategies using non-thermal technologies offers prospects to develop plant-based products with enhanced bioaccessibility of their bioactive compounds and micronutrients. In this review, we attempt to provide updated information regarding the main effects of PEF, HPP, HPH, and US on health-related compounds bioaccessibility from different vegetable matrices and the causes underlying these changes. Additionally, we propose future research on the relationship between the bioaccessibility of bioactive compounds and micronutrients, matrix structure, and non-thermal processing.

The effect of nanosecond pulsed electric field on the production of metabolites from lactic acid bacteria in fermented watermelon juice

Lactic acid fermentation offers a processing alternative for preservation of watermelon juice, which is sensitive to heat, oxygen, and light. In this study, 8.8 × 107 CFU/mL of Lactobacillus plantarum DSM 9843 in MRS broth was inoculated in 9.9 mL of sterilized watermelon juice. Nanosecond-pulsed electric field was applied during the log growth phase of the bacteria. An 19% increase in L-lactic acid, 6.8% increase in D-lactic acid and 15% increase in acetic acid were observed over control. The final pH was 3.8. These increased levels of metabolites were dependent on the applied voltages (L-lactic acid: 5.0 kV 700 pulses, D-lactic acid: 4.5 kV 700 pulses and acetic acid: 4.5 kV 1000 pulses). The nsPEF treatment did not affect the viability of the cells and sufficient numbers remained in the product after fermentation (1.6 × 109 CFU/mL in average). These results suggest that the metabolism of lactic acid bacteria was stimulated by the PEF treatment.

Effects of pulse electric field pretreatment on the frying quality and pore characteristics of potato chips

The main purpose of this work was to investigate the effect of pulsed electric field (PEF) treatment on the oil absorption capacity of potato chips, evaluated via changes to microstructure and pore characteristics. Our results showed that as electric field strength increased from 0 kV/cm (no pretreatment) to 5 kV/cm, the oil content of potato chips decreased by up to 20.6%. Furthermore, at higher the electric field strengths (5 ~ 20 kV/cm), most of the potato cell walls collapsed, and dense pores could be observed in the horizontal profile of the chips. Moreover, some smaller pores (10–50 nm) in the potato chips were disrupted and merged into larger pores (50–100 nm), thus increasing the total volume and average diameter of the pores, accelerating moisture evaporation and reducing oil absorption during frying. Our findings provide a novel perspective on the application of PEF towards the development of lower-fat and healthier fried foods.

Use of Pulsed Electric Field as a Low-Temperature and High-Performance “Green” Extraction Technique for the Recovery of High Added Value Compounds from Olive Leaves

Olive leaves (OLL), an agricultural waste by-product, are considered a significant bioresource of polyphenols, known as bioactive compounds. This study evaluates the pulsed electric field (PEF) technique for the extraction of polyphenols from OLL. The study parameters included a series of “green” solvents (ethanol, water as well as mixtures of them at a 25% step gradient) and different input values for the pulse duration of PEF. The phytochemical extraction degree was evaluated using total phenol concentration (Folin–Ciocalteu method) and high-performance liquid chromatography (HPLC) analyses, while the antioxidant activity was assessed using differential scanning calorimetry (DSC). The results obtained from the PEF extracts were compared with those of the extracts produced without the PEF application. The highest PEF effect was observed for aqueous ethanol, 25% v/v, using a pulse duration of 10 μs. The increase in the total polyphenols reached 31.85%, while the increase in the specific metabolites reached 265.67%. The recovery in polyphenols was found to depend on the solvent, the pulse duration of treatment and the structure of the metabolites extracted.

Combined effects of pulsed electric field and ultrasound pretreatments on mass transfer and quality of mushrooms

This study aimed to investigate the effects of pulsed electric field (PEF), ultrasound (US), and combined pretreatments (PEF-US) on mass transfer, rehydration capacity, microstructure, and nutritional quality of shiitake mushrooms (Lentinus edodes). The results indicated that pretreatments could accelerate mass transfer during the hot-air drying process at 65 °C, resulting in lower drying time and energy requirement than control. Meanwhile, the low-field nuclear magnetic resonance (LF-NMR) analysis revealed better rehydration capacity of the pretreated groups than the untreated group. The results of scanning electron microscopy (SEM) demonstrated that pretreatments significantly changed the cell structure by developing intracellular space and larger cavities and facilitating the drying and rehydration process of mushrooms. Additionally, the physiochemical analysis illustrated that pretreatment could preserve the color and nutritional quality more effectively than the untreated groups. Of the pretreatment groups, the shortest drying time was observed in the combined (PEF-US) group (4.7 h). The PEF-US pretreated mushroom also exhibited the highest phenolics (224.17 μg/μL) and soluble sugar (3.90 mg/mL) levels. Overall, the study concluded that the combined pretreatment group (PEF-US) was a promising pretreatment method for hot-air drying of mushroom products to improve the drying efficiency, product quality control, and nutritional value protection.

Pulsed electric fields‐ and ultrasound‐assisted green extraction of valuable compounds from Origanum vulgare L. and Thymus serpyllum L.

SummaryThis work compared the effects of pulsed electric fields (PEF) and ultrasound (US) technologies on the extent of cell disintegration of two Mediterranean herb tissues (Origanum vulgare L., Thymus serpyllum L.), as well as on the extractability of phenolic compounds during the subsequent hydroalcoholic extraction (0%–50% ethanol in water, v/v) for up to 4 h. The rate of phenolic compounds extraction decreased with time and was predicted rather satisfactorily (R2 = 0.898–0.989) by the Peleg’s model. The application of either PEF or US treatment prior to solid–liquid extraction (SLE) has the potential to reduce duration and concentration of ethanol to achieve the same recovery yield of phenolic compounds. Under optimised PEF (3 kV cm−1, 10 kJ kg−1) and US (400 W, 20 min) treatment conditions, the extracts obtained from either PEF or US pretreated herb samples showed higher total phenolic yield (36% on average) and antioxidant activity (FRAP) (36% on average) as compared to the control extraction, especially when 25% ethanol was used as a solvent. GC/MS analyses revealed no evidence of degradation of individual phenolics due to either PEF or US application.

Effect of pulsed electric field treatment on the kinetics of rehydration, textural properties, and the extraction of intracellular compounds of dried chickpeas.

This study investigated the effect of pulsed electric fields (PEF) pretreatment on rehydration kinetics, firmness, and release of intracellular components of dried chickpeas during rehydration at 35 to 65°C. After soaking preconditioning, chickpeas were subjected to PEF treatments (2.5 and 3.3kV/cm, 0.2 to 12.0kJ/kg, 15 µs pulse width, 20Hz frequency). PEF treated and untreated chickpeas were dried in crossflow air dryer and their rehydration at constant seed/water ratio of 1:5 was studied for 24 hr. During rehydration, moisture, firmness, and concentration of released proteins, carbohydrates and raffinose family oligosaccharides (RFO) were determined and described using appropriate mathematical models. PEF treatment led to up to 70% higher rehydration rates of dried chickpeas. This increase corresponds to rehydration time of approximately 1.5 hr, as opposed to 5 hr for untreated samples. Firmness of PEF treated chickpeas (for energy inputs higher than 3kJ/kg) during rehydration decreased up to 30% compared to untreated samples. The firmness of untreated samples after 300min of rehydration was achieved at much shorter times (up to 30min) for PEF treated samples. At the end of 300min of rehydration, more than 47.7%, 76.1%, and 86.6% of total raffinose, stachyose, and verbascose, respectively has been extracted, but only 0.03% of nutritionally valuable proteins from PEF treated chickpeas. Consequently, this study demonstrates that PEF processing could be implemented in dried chickpeas processing as pretreatment, for the reduction of rehydration time prior to cooking and of intestinal discomfort caused by RFO.

A nanosecond pulsed electric field (nsPEF) can affect membrane permeabilization and cellular viability in a 3D spheroids tumor model

Three-dimensional (3D) cellular models represent more realistically the complexity of in vivo tumors compared to 2D cultures. While 3D models were largely used in classical electroporation, the effects of nanosecond pulsed electric field (nsPEF) have been poorly investigated. In this study, we evaluated the biological effects induced by nsPEF on spheroid tumor model derived from the HCT-116 human colorectal carcinoma cell line. By varying the number of pulses (from 1 to 500) and the polarity (unipolar and bipolar), the response of nsPEF exposure (10 ns duration, 50 kV/cm) was assessed either immediately after the application of the pulses or over a period lasting up to 6 days. Membrane permeabilization and cellular death occurred following the application of at least 100 pulses. The extent of the response increased with the number of pulses, with a significant decrease of viability, 24 h post-exposure, when 250 and 500 pulses were applied. The effects were highly reduced when an equivalent number of bipolar pulses were delivered. This reduction was eliminated when a 100 ns interphase interval was introduced into the bipolar pulses. Altogether, our results show that nsPEF effects, previously observed at the single cell level, also occur in more realistic 3D tumor spheroids models.

Extraction of volatile aroma compounds from toasted oak wood using pulsed electric field

The effect of pulsed electric field (PEF) on the extraction of volatile compounds from toasted oak wood chips immersed in various aqueous ethanol solutions (5%, 12%, 50%, and 70% vol/vol) was determined by Gas chromatography/mass spectrometry (GC/MS) after ultrasound-assisted extraction. PEF treatment showed the highest impact in the 5% solution, increasing vanillin, syringaldehyde, oak lactone (cis- and trans-), and furfural by 75%, 371%, 13%, and 50%, respectively. PEF was also tested on Agiorgitiko red wine and on malt and wine distillates. In wine distillate, 4-vinylguaiacol was also detected. For red wine, a PEF of 1.2 kV/cm increased the efficiency of extraction of wood aroma compounds from 5% to 200%. Differences in the extracted volatile compound concentrations between the control and PEF-treated samples were also observed in the malt and wine distillates. The sensory evaluation showed that the PEF-treated malt was similar to an aged whiskey, having nuances of toasted oak. Practical applications This work was done as a preliminary investigation for our on-going research into the application of PEF technique for the extraction of aromatic compounds from oak wood, and the acceleration of both wine and malt distillate aging. The findings suggest that PEF could be introduced in wine, brandy, and whiskey industry as a novel technology for the acceleration of the aging process.

Retention of polyphenols and vitamin C in cranberrybush purée (Viburnum opulus) by means of non-thermal treatments

The effects of high pressure processing (HPP; 200–600 MPa for 5 or 15 min) and pulsed electric field (PEF; 3 kV/cm, 5–15 kJ/kg) treatment on physicochemical properties (conductivity, pH and total soluble solids content), bioactive compounds (vitamin C, total phenolic (TPC), total flavonoid (TFC), total anthocyanin (TAC) and chlorogenic acid contents), antioxidant capacities (DPPH and CUPRAC assays) and polyphenol oxidase (PPO) activity of cranberrybush purée were evaluated immediately after processing. The results were compared to an untreated purée. According to the results, conductivity increased significantly after PEF (15 kJ/kg) treatment. PEF and HPP treatments resulted in a better retention of bioactive compounds (increase in TPC in the range of ~4–11% and ~10–14% and TFC in the range of ~1–5% and ~6–8% after HPP and PEF, respectively) and antioxidant activity (as measured with CUPRAC method) compared to untreated sample. HPP reduced residual enzyme activity of PPO comparatively better than PEF.

Design and Development of Mini-pulsar for Real-Time Bioelectric Experiment

Investigation of the effect of pulsed electric field on eukaryotic cells has been of interestto biomedical scientists and researchers since a few decades. Reversible electroporation (EP) is used for uptake of chemicals, drugs, DNA into the eukaryotic cells under low electric field (100’s V/cm) of millisecond duration to few hundreds of microsecond duration. An electric field of nanosecond duration and a very high electric field (50’s kV/cm) can stress to intracellular organelles of eukaryotic cells and that can trigger apoptotic pathways. In this article experimental setup has been prepared for real-time investigation of the effect of nanosecond electric field on eukaryotic cells. Pulsar producing ~1.5kV, 20ns FWHM, single shot as well as ~10Hz rep-rate with rise-time as fast as ~10ns, has been prepared using blumlein pulse forming line and avalanche transistor switches. A 300µm gap microplate chamber has been prepared to expose the electric fieldtoeukaryotic cells.