How Electroporation Uses Electric Pulses to Open Cells

Electroporation is a technique that uses brief, high-voltage electrical pulses to open temporary pores in cell membranes, allowing molecules that normally cannot cross the membrane to slip inside. It has become one of the most versatile tools in modern biology and medicine, used for everything from inserting genes into lab-grown cells to destroying tumors, treating heart arrhythmias, preserving food, and even extracting useful compounds from algae. The underlying principle is simple enough, but the range of problems it solves keeps growing.

How Electrical Pulses Open a Cell Membrane

Every living cell is surrounded by a thin lipid membrane that acts as a selective barrier. When you expose that membrane to a strong electric field, the voltage builds across the membrane faster than the cell can dissipate it. Once the induced voltage exceeds a certain threshold, the membrane’s lipid molecules rearrange and tiny water-filled channels, or pores, form through the barrier. Molecular simulations have shown the process in detail: thin “fingers” of water molecules push into the membrane’s oily interior from both sides, eventually linking up to form continuous water wires that span the full thickness of the membrane. Once those channels exist, polar headgroups from the membrane lipids migrate inward and stabilize the pore walls, creating passageways large enough for drugs, DNA, proteins, or dye molecules to flow through.

Whether the pores heal afterward or the cell dies depends on pulse strength, duration, and the number of pulses delivered. At moderate settings, pores reseal within seconds to minutes and the cell survives, a scenario researchers call reversible electroporation. Push the energy higher and the membrane damage becomes too extensive to repair, killing the cell through what is known as irreversible electroporation. In one study on liver cancer cells, an electric field of about 1,000 V/cm using eight short pulses was enough to open membranes while keeping cells alive, whereas roughly 4,000 V/cm with 70 pulses caused near-total cell death.¹ That gap between “open the door” and “destroy the house” is what makes electroporation so adaptable.

Cell orientation and temperature also matter. Cardiac muscle cells, for instance, are more easily killed when positioned perpendicular to the electric field than when aligned parallel to it.² And the lethal field strength drops substantially when tissue starts at body temperature rather than a cooler starting point, because warmer membranes are already more fluid and easier to disrupt.³

Getting Molecules Into Cells in the Lab

The oldest and still most common use of electroporation is transfection: getting foreign DNA, RNA, or proteins into cells that would otherwise reject them. The technique first proved itself in the 1980s when researchers showed they could electrically introduce DNA into plant protoplasts from carrot, tobacco, and maize, establishing that the method works across both major divisions of flowering plants.⁴ Optimized protocols for tobacco protoplasts now routinely achieve transgene expression frequencies approaching 90%.⁵

In mammalian cell work, electroporation shines for “difficult-to-transfect” cells that resist chemical delivery methods. Primary human fibroblasts, immune cells, endothelial cells, and neuroblastoma lines have all been electroporated with plasmid DNA and small interfering RNA at efficiencies above 75%, and in some cases above 90%.⁶ Human embryonic stem cells, which are famously finicky, can also be loaded with molecules ranging from small dyes to large fusion proteins and plasmid DNA, though each cargo size requires different pulse timing. Short pulses on the order of 0.05 milliseconds work for small molecules, while half a millisecond or longer is needed for bulky proteins and DNA.⁷

A persistent challenge is that higher voltage and more pulses improve delivery but kill more cells. Combined-pulse strategies try to thread that needle by starting with a brief high-voltage pulse to punch open the membrane and immediately following it with a longer, lower-voltage pulse to drive cargo inside. In one comparison, this approach transfected both a mouse cell line and primary mouse fat-cell precursors at around 90 to 95%, significantly outperforming a leading commercial device.⁸ Even so, electroporation typically halves the number of viable cells recovered after 24 hours compared with untreated controls, a trade-off researchers accept because the surviving cells are so efficiently modified.

Electroporation for CRISPR Gene Editing

The rise of CRISPR-Cas9 genome editing created new demand for electroporation, because the editing machinery works best when delivered as a pre-assembled protein-RNA complex rather than as a DNA plasmid. Electroporation gets that complex into the cell quickly without integrating any foreign DNA into the genome, which matters both for research accuracy and for any future therapeutic use.

In primary liver cells freshly isolated from human donors, electroporating the Cas9 protein-guide RNA complex achieved a mean editing efficiency of about 78%, compared with roughly 47% for Cas9 delivered as messenger RNA, and the procedure did not harm the cells’ ability to survive or function normally.⁹ Protocols have also been optimized for human induced pluripotent stem cells, where electroporation can introduce single-letter DNA changes or insert sequences at precise spots without needing antibiotic selection to find the edited cells.¹⁰

One concern with earlier CRISPR delivery was that editing efficiency dropped dramatically in primary human cells compared with standard lab cell lines. Work using a tube electroporation method has largely closed that gap, showing that when the protein-RNA complex is delivered efficiently, editing rates stay consistent across multiple cell types, including hard-to-transfect human stem cells and T cells.¹¹ That consistency is a big deal for cell therapies, where the goal is to edit a patient’s own immune cells and return them to the body.

DNA Vaccines and Immune Response

DNA vaccines work by injecting a small circular piece of DNA encoding part of a pathogen into muscle or skin, where cells take it up, produce the encoded protein, and trigger an immune response. The problem is that naked DNA injected on its own enters cells poorly. Applying electroporation pulses at the injection site can boost antigen delivery by as much as a thousandfold, translating into stronger and more reliable immune responses that in many studies have matched or exceeded those from viral-vector vaccines and traditional live or inactivated virus vaccines.¹² Several DNA vaccine candidates delivered with electroporation have entered human clinical trials for diseases including HIV, hepatitis, and various cancers.

Destroying Tumors Without Heat

Irreversible electroporation has carved out a role in oncology as an ablation method for tumors that sit too close to critical blood vessels, bile ducts, or nerves for heat-based treatments like radiofrequency ablation to be safe. Because it kills cells by destabilizing membranes rather than cooking tissue, the surrounding structural scaffolding, blood vessels, and nerve fibers tend to survive, allowing the treated area to heal more normally.¹³ The commercial device used most widely goes by the name NanoKnife.

Pancreatic cancer is one of the tumors where irreversible electroporation has attracted the most interest, precisely because unresectable pancreatic tumors often wrap around major arteries and veins that thermal ablation would damage.¹⁴ Prostate cancer is another active area, with a prospective development study describing irreversible electroporation’s precise treatment boundaries as attractive for focal ablation that aims to destroy just the tumor while sparing erectile and urinary function.¹⁵

A separate strategy called electrochemotherapy uses reversible electroporation to boost the uptake of chemotherapy drugs directly at the tumor site. The anti-cancer drug bleomycin, for example, is highly toxic once inside a cell but normally cannot cross the membrane. Applying electric pulses after injecting bleomycin into a tumor increases the drug’s cytotoxicity several hundredfold, allowing much lower total drug doses and fewer systemic side effects.¹⁶ Electrochemotherapy is used clinically in Europe for skin and subcutaneous tumors, particularly melanoma metastases.

Treating Heart Arrhythmias With Pulsed Fields

One of the fastest-growing medical applications of electroporation is pulsed field ablation for atrial fibrillation, the most common heart rhythm disorder. Traditional catheter ablation uses heat (radiofrequency energy) or extreme cold (cryoablation) to destroy the small patches of heart tissue that generate the erratic electrical signals behind atrial fibrillation. Both methods work, but they can accidentally injure the esophagus, the phrenic nerve that controls the diaphragm, or the pulmonary veins, which may narrow after thermal injury.

Pulsed field ablation replaces thermal energy with ultra-short, high-voltage electrical pulses that kill heart muscle cells through irreversible electroporation. Heart muscle cells happen to be among the most sensitive tissue types to pulsed electric fields, which means the energy needed to destroy them is lower than what would damage surrounding structures like nerves, blood vessels, and the esophagus.¹⁷ This tissue selectivity is the central selling point. Because the mechanism avoids coagulative necrosis, the risk of pulmonary vein stenosis is theoretically eliminated.¹⁸ Pulse delivery also takes only a few seconds per application, compared with the longer dwell times required for heat or cold. Multiple pulsed field ablation catheters have received regulatory clearance and are now in clinical use.

Delivering Drugs Through the Skin

Skin electroporation applies short high-voltage pulses to the outermost layer of skin, the stratum corneum, which is the main barrier to topical drug absorption. The pulses create transient disruptions in the lipid layers between skin cells, dramatically increasing the passage of drugs that would otherwise be blocked. Early measurements on human skin showed flux increases of up to four orders of magnitude for polar molecules with molecular weights slightly above 1,000.¹⁹ The technique works on a wide range of molecules regardless of size, charge, or whether they dissolve in water or fat, and it can be combined with other enhancement methods like iontophoresis for even greater delivery.²⁰ Transdermal electroporation remains mostly in the research and specialty-device stage, but the concept of painlessly pushing larger drug molecules through skin without needles continues to draw interest for insulin delivery, local anesthetics, and cosmetic applications.

Food Processing and Preservation

Outside of biology labs and hospitals, pulsed electric fields based on the same electroporation principle have found a growing foothold in the food industry. When applied to liquid foods like fruit juices, short high-voltage pulses kill bacteria and spoilage organisms by rupturing their membranes, achieving preservation with far less heat than pasteurization. Because the process barely raises the temperature of the product, it preserves flavor, color, and heat-sensitive vitamins better than thermal methods.²¹

Beyond killing microbes, pulsed electric fields are increasingly used as a pre-treatment step. By permeabilizing the cell walls of fruits, vegetables, and other raw materials, the technology makes it easier to extract juice, speed up drying, and pull out nutrients, all at lower energy costs than mechanical or chemical alternatives.²² French fry manufacturers, for example, use pulsed electric field treatment to soften potatoes before cutting, reducing breakage and producing a better texture after frying. Wineries have explored it to enhance extraction of color and flavor compounds from grape skins.

Harvesting Algae Without Destroying Them

Microalgae are a promising source of proteins, lipids, and biofuels, but getting valuable molecules out of their tough cell walls usually requires energy-intensive mechanical grinding or chemical solvents. Electroporation offers a gentler alternative. By applying controlled pulses to algae cultures, researchers can open the cell membranes just enough to release intracellular proteins into the surrounding liquid while keeping the cells largely intact and able to regrow. One study on the common green alga Chlorella vulgaris demonstrated that electroporation could extract proteins in a largely debris-free way, without any need for drying or concentrating the culture first, and the cells could regenerate afterward.²³

When the goal is lipid extraction for biodiesel rather than protein, stronger pulses can be used. Pulsed electric field treatment of Chlorella boosted lipid extraction yields by up to about 167% compared with untreated samples, with the degree of improvement tracking closely with field strength and total energy input.²⁴ The ability to tune the pulse parameters and control how much membrane damage occurs is what makes the technique attractive: you can choose whether to milk the algae gently over repeated cycles or crack them open fully for maximum one-time yield.

Sewage Sludge and Waste Treatment

An application that rarely makes headlines but has real environmental potential is using pulsed electric fields to pre-treat sewage sludge before anaerobic digestion. Municipal wastewater treatment generates enormous volumes of biological sludge that is broken down by bacteria in oxygen-free digesters, producing methane that can be captured for energy. The bottleneck is that intact microbial cells in the sludge are slow to break apart, limiting how much methane the digester can produce. Applying pulsed electric fields to the sludge before digestion ruptures many of those cells, releasing their contents and making them available to the digester bacteria much faster. In one study, pretreated sludge produced 1.7 times more methane than untreated sludge.²⁵ Earlier laboratory-scale work confirmed that pulsed electric fields consistently improved anaerobic degradation performance and could partially destroy problematic filamentous bacteria that cause foaming in digesters.²⁶

Reducing Muscle Contractions and Pain

One practical hurdle for clinical irreversible electroporation is that the strong electrical pulses cause involuntary muscle contractions. In tumor ablation procedures, patients typically receive general anesthesia plus a neuromuscular blocking agent (a paralytic drug) to prevent dangerous movement during treatment. Eliminating that requirement would simplify the procedure and reduce anesthesia-related risks.

High-frequency irreversible electroporation, sometimes called H-FIRE, addresses this by replacing the traditional single long monopolar pulses with rapid bursts of very short bipolar pulses. In an early proof-of-concept study, bipolar bursts at 250 kHz and 500 kHz produced tissue ablation without any visible or detectable muscle contraction, while all conventional monopolar pulse protocols triggered contractions.²⁷ Follow-up work in an animal model confirmed that high-energy bursts of 2-microsecond alternating-polarity pulses caused less intense contractions than traditional pulses even at higher voltages.²⁸ Human studies have similarly found that biphasic high-frequency pulses with widths of 1 or 2 microseconds reduce both muscle contraction and pain sensation compared with longer monophasic pulses.²⁹ This shift toward shorter, bipolar pulses is already influencing the design of next-generation clinical devices, including the pulsed field ablation catheters used in cardiology.

Shrinking the Hardware With Microfluidics

Conventional electroporation systems apply pulses across a cuvette holding millions of cells at once, which means every cell in the chamber experiences a slightly different field depending on its position. Microfluidic electroporation shrinks the electrode gap to the micrometer scale, achieving the necessary field strengths at voltages below 50 volts. That dramatically reduces the heat generated by the pulse and the harmful electrolysis byproducts that can damage cells in bulk systems.³⁰ Some nanostructure-assisted designs even achieve subcellular precision, opening pores at a specific spot on a single cell while monitoring the process in real time.

For cell therapy manufacturing, where billions of modified immune cells need to be produced for a single patient dose, continuous-flow microfluidic devices offer a path to high throughput with tight quality control. One such device demonstrated up to 95% transfection efficiency when delivering messenger RNA into primary human T cells, with minimal impact on the cells’ ability to survive and expand afterward.³¹ Scaling this kind of precision from bench to production floor is one of the active frontiers in the field.

How Cells Repair After Electroporation

When electroporation is reversible, pores eventually close and the membrane reseals. The details of how cells accomplish this repair are still being worked out. Calcium ions flooding in through newly opened pores trigger repair pathways, and removing calcium from the outside slows resealing, though it does not prevent it entirely. One candidate repair mechanism involves Annexin V proteins, which bind to damaged patches of membrane in the presence of calcium. However, another pathway that cells use to shed damaged membrane patches, the ESCRT-III complex, does not appear to play a role in repairing pores created by very short nanosecond pulses, at least in the cell types tested so far.³² The fact that repair can proceed even without calcium suggests multiple overlapping mechanisms are at work, and the specific repair strategy likely depends on pulse parameters and cell type. Understanding these mechanisms better could eventually let researchers fine-tune pulse protocols to either maximize cell survival or ensure complete cell death, with less guesswork.

Computational Treatment Planning

Getting electroporation to work well in living tissue, rather than in a controlled lab dish, requires understanding how electric fields distribute themselves through materials of different conductivities. Skin, fat, muscle, and tumor tissue all conduct electricity differently, and that conductivity itself changes as cells become electroporated and their membranes open. Computational models that account for this feedback loop, where the electric field changes the tissue and the changed tissue reshapes the electric field, fit real-world experimental data much better than simpler models that assume fixed conductivity.³³ Without this correction, simulations can drastically underestimate how deeply the treatment penetrates into a tumor buried under resistive skin.

Newer models are also beginning to incorporate the effect of changing the electric field direction between successive pulses and the increased conductivity of tissue that has already been irreversibly electroporated from earlier pulses in the treatment sequence.³⁴ These refinements matter for clinical planning because they help predict the size and shape of the ablation zone before the procedure starts, reducing the chance of leaving viable tumor behind or damaging healthy tissue unnecessarily. As treatment planning software matures, the hope is that electroporation-based therapies become as precisely targetable as modern radiation therapy, with individualized dose maps computed from each patient’s imaging.