{"id":20139,"date":"2026-09-17T15:51:41","date_gmt":"2026-09-17T08:51:41","guid":{"rendered":"https:\/\/www.tibdglobal.com\/?p=20139"},"modified":"2026-10-01T18:26:49","modified_gmt":"2026-10-01T11:26:49","slug":"what-is-cold-plasma","status":"publish","type":"post","link":"https:\/\/www.tibdglobal.com\/en\/what-is-cold-plasma\/","title":{"rendered":"What Is Cold Plasma? An Interview with Assoc. Prof. Dr. Siwapon Srisonphan"},"content":{"rendered":"
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Interviewed and edited by Dr. Wuttipong Panitsettakorn, Managing Director, TIBD Company Limited \u00b7 Recorded 11 September 2025<\/em><\/p>

A conversation with Assoc. Prof. Dr. Siwapon Srisonphan, Department of Electrical Engineering, Kasetsart University, on the cold plasma technology behind the work<\/strong><\/p>

Cold plasma is the fourth state of matter, generated close to room temperature, which is what allows it to touch seeds, fresh produce and skin without thermal damage.<\/p>

The technology has been discussed internationally for years, yet almost nobody in Thailand has actually used it. Not because it does not work, but because of what it used to cost.<\/p>

Assoc. Prof. Dr. Siwapon Srisonphan teaches in the Department of Electrical Engineering, Faculty of Engineering, Kasetsart University.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][\/vc_section][vc_row][vc_column]\n\t\t

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<\/span>What cold plasma is, explained without a single equation<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

Matter as we know it has three familiar states: solid, liquid, and gas. Give a gas enough energy that its electrons break away from their atoms and it turns into a fourth state, called plasma.<\/p>

In nature we meet plasma in the sun, in lightning, and in the aurora, all of them extremely hot.<\/p>

Cold plasma, or non-thermal plasma, is that same state produced close to room temperature. The principle is to accelerate only the electrons, which carry almost no mass, so the much heavier molecules of the gas stay cool. The result is reactive chemistry on a material that never heats up.<\/p>[\/vc_column_text][vc_single_image image=”19856″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

The violet glow is plasma struck in air at ordinary pressure. Objects right beside it do not get hot.<\/em><\/p>[\/vc_column_text][vc_column_text woodmart_inline=”no” text_larger=”no”]

How cold plasma works, in four steps<\/strong><\/p>

  • It starts from ordinary air. Nothing is added to the process.<\/li>
  • A high electric field breaks the air apart, creating reactive oxygen and nitrogen species (RONS).<\/li>
  • Those species react at the surface of the target, reducing microorganisms and changing the surface condition.<\/li>
  • Once they have acted, they decay back into ordinary air. Nothing accumulates.<\/li><\/ul>

    Because cold plasma is generated at ordinary atmospheric pressure, it needs no vacuum system of the expensive kind the semiconductor industry depends on. That is the single fact that lets it start leaving the laboratory.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>A question set more than ten years ago<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    His route into this did not start in agriculture. It started with chips.<\/p>

    After graduating in electronic engineering from King Mongkut’s Institute of Technology Ladkrabang with first-class honours, he took a Ministry of Science and Technology scholarship for a master’s degree at the University of Texas at Austin, then a PhD at the University of Pittsburgh.<\/p>

    The field he worked in was nanoelectronics, the same level of work that goes into CPUs and graphics cards (GPUs). One of his papers was published in Nature Nanotechnology, on a transistor with a vacuum channel inside it.<\/p>

    Then he came home.<\/p>

    \u201cWhen I got back to Thailand, I found that one of the hardest technologies to get hold of was plasma, because it took a substantial budget. So that became my problem, more than ten years ago: how do we make plasma technology easy to reach and easy to use?\u201d<\/p><\/blockquote>

    \u2014 Assoc. Prof. Dr. Siwapon Srisonphan<\/em><\/p>

    It is still the same question today. What has changed is the answer.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>Why he chose a lab where you build your own instruments<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    What is striking is that he prepared for this before he had even finished studying. When he chose a university for his PhD, he did not pick the lab with the best equipment. He picked the one where every instrument had to be built from scratch.<\/p>

    \u201cI wanted to study in a lab that built everything from zero, because I could see that when I returned to Thailand I might have to build the equipment myself before I could do any research at all.\u201d<\/p><\/blockquote>

    It was a decision made a very long way ahead, and it turned out to be right.<\/p>

    \u201cWhen we came back to Thailand we had nothing. None of the equipment we had trained on was here. We could not do anything. So we spent time looking at what was around us, and stepped back to ask what we actually could build.\u201d<\/p><\/blockquote>

    What he could build was plasma struck by electrical discharge in ordinary air. That became the work he is known for.<\/p>[\/vc_column_text][vc_single_image image=”19858″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    Several plasma heads running together, one of the ways to answer the question of volume.<\/em><\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>What cold plasma can be used for<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    The shortest answer is that it works on living and non-living material alike, from the level of a single cell up to a production line.<\/p>

    \u201cIf we treat plasma as a tool, how do we design and use it to replace what is a problem today, or to do what current technology cannot?\u201d<\/p><\/blockquote>

    <\/span>Seed and cultivation<\/span><\/h3>

    Cold plasma is used to condition the seed surface so it takes up water better, which affects how evenly the crop germinates, while reducing the microorganisms carried on the seed coat, with no chemical coating. This group of work has been carried on by Thai research teams for years and has been published in international journals.<\/p>[\/vc_column_text][vc_single_image image=”19860″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    An array of plasma heads firing onto seed moving past on a conveyor, a test at a scale larger than a petri dish.<\/em><\/p>[\/vc_column_text][vc_column_text woodmart_inline=”no” text_larger=”no”]

    <\/span>Food safety and extending the shelf life of fresh produce<\/span><\/h3>

    In the food industry, cold plasma is used to reduce microorganisms on the surface of raw materials and on packaging. Its advantage is that the process uses no heat, so it does not damage the quality of fresh food, and it leaves no residue the way a disinfectant chemical does.<\/p>

    Reducing the microbial population on the surface of produce slows spoilage, which is why this area appears in the international literature as cold plasma food processing, and why it has been tested against shelf-life problems in a number of countries.<\/p>[\/vc_column_text][vc_single_image image=”19862″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    A handheld plasma head tested on the skin of a strawberry. The fruit does not get hot during the test.<\/em><\/p>[\/vc_column_text][vc_column_text woodmart_inline=”no” text_larger=”no”]

    <\/span>Material surfaces and packaging<\/span><\/h3>

    On non-living material such as glass, metal and plastic, cold plasma is used to clean and condition the surface before the next step, such as printing, coating or bonding, so that it adheres better without a solvent.<\/p>

    <\/span>Skin and medical applications<\/span><\/h3>

    He says his first interest was not agriculture at all. About ten years ago he read research from Germany showing that cold plasma could inactivate viruses. Later it turned out to handle bacteria as well, and medical research abroad began applying it to certain kinds of wound care.<\/p>

    What particularly interested him was the property described as selectivity: acting on certain targets without destroying everything around them.<\/p>[\/vc_column_text][vc_single_image image=”19864″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    A handheld plasma head under test on skin. This group of work is still at research stage, not a registered product.<\/em><\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>Terms you will meet when you search further<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    This field goes by several names, and different sources use them differently. This table lines them up so you can search the research and technical literature with the right words.<\/p>
    Term<\/th>What to search for<\/th>What it means<\/th><\/tr><\/thead>
    Cold plasma<\/td>Cold Plasma<\/td>Plasma generated close to room temperature, so it can be brought into contact with living material.<\/td><\/tr>
    Non-thermal plasma<\/td>Non-thermal Plasma (NTP)<\/td>The academic term for the same thing as cold plasma.<\/td><\/tr>
    Atmospheric pressure plasma<\/td>Atmospheric Pressure Plasma<\/td>Plasma that needs no vacuum system, so it can sit in a production line.<\/td><\/tr>
    Plasma-activated water<\/td>Plasma Activated Water (PAW)<\/td>Water energised by plasma until it carries antimicrobial activity.<\/td><\/tr>
    Plasma seed treatment<\/td>Plasma Seed Treatment \/ Seed Priming<\/td>Using plasma on seed, for germination and for reducing microorganisms on the seed coat.<\/td><\/tr>
    Plasma sterilization<\/td>Plasma Sterilization<\/td>Reducing microorganisms with plasma, without heat and without adding a chemical.<\/td><\/tr>
    Cold plasma food processing<\/td>Cold Plasma Food Processing<\/td>Using plasma along a food production line and on packaging.<\/td><\/tr>
    Dielectric barrier discharge<\/td>Dielectric Barrier Discharge (DBD)<\/td>A plasma format that uses a dielectric sheet as a barrier. It suits solids and seed.<\/td><\/tr>
    Gliding arc<\/td>Gliding Arc<\/td>A higher-power plasma format. It suits liquids and gases.<\/td><\/tr><\/tbody><\/table>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t
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    <\/span>Process innovation, not product innovation<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    Asked what kind of innovation this is, he is clear: today it is process innovation rather than product innovation.<\/p>

    Plasma is a step that goes into a production line to make the end product worth more, or to make a product that was not possible before. In some cases the process itself becomes the product, as with plasma-activated liquids.<\/p>

    That distinction matters commercially, because it means adopting cold plasma does not mean tearing up an existing product. It means adding one step to a process that already exists.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>The hardest problem is not the science. It is scale.<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    In the laboratory this is not hard to prove. The real problem sits just past that point.<\/p>

    \u201cThe question is that we do this ten seeds at a time, but we are talking about tens of thousands of kilograms. So how do we get there? Plasma is not afraid of working small. It is afraid of working big.\u201d<\/p><\/blockquote>

    This is the gap where a great deal of research stops short, not because the science is wrong, but because scale-up is a different problem from proving that something works, and it takes a different budget and a different set of engineering.<\/p>

    Five years ago, he says, producing plasma-activated liquid in Thailand was difficult even a few litres at a time. His team solved that by designing a new discharge system, and has begun sending samples out to companies to test in their own settings.<\/p>[\/vc_column_text][vc_single_image image=”19866″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    Plasma struck directly on the water surface. That is how plasma-activated water is made.<\/em><\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>\u201cPlasma is not magic\u201d<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    What sets this conversation apart from the usual researcher interview is that he is not selling anything.<\/p>

    Asked where the technology stands in Thailand, he answers plainly that taking it into industrial use is still harder and further off than many people assume. The research funding available tends to carry work only as far as basic research, and funded research does not always answer what industry actually needs.<\/p>

    Plasma, he says, is not a magic answer to everything. Conditions that suit one industry may not carry over to another at all. What matters most is matching it properly to the product and the process in front of you.<\/p>

    Abroad, in the United States, South Korea and Japan, products using this technology are already reaching the market. Thailand is still at the starting line, but he sees the gap as small, and thinks it now comes down to who matches the technology to the right problem first.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>What he wants is not research funding<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    Asked what he would say to industry, the answer is not the expected one.<\/p>

    \u201cWe do not know everything, and we are not good at everything. Problems that come from industry are exactly what interests us.\u201d<\/p><\/blockquote>

    \u2014 Assoc. Prof. Dr. Siwapon Srisonphan<\/em><\/p>

    What he says he really wants is a business model, because research that lasts has to move together with a product. A strong product comes from strong research, and research only stays strong when it has somewhere real to land.<\/p>

    The industries that interest him most are food and agriculture, for the simple reason that they are what this country runs on.<\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>Same question, new answer<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    \u201cThe semiconductor industry needs vacuum systems, and those are very expensive. What we are interested in now needs no vacuum. You switch it on and use it. It can sit on a conveyor. You can hold it in your hand.\u201d<\/p><\/blockquote>

    That is the answer to the question he has carried for more than ten years, and it is why this technology is beginning to leave the laboratory now.<\/p>[\/vc_column_text][vc_single_image image=”19868″ img_size=”full” alignment=”center” style=”vc_box_rounded” css=”” parallax_scroll=”no” woodmart_inline=”no”][vc_column_text woodmart_inline=”no” text_larger=”no”]

    No vacuum system needed, so it can sit above a conveyor in a production line.<\/em><\/p>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column]\n\t\t

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    <\/span>Five things worth taking away<\/span><\/h2>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\n\t\t\t\n\t\t\t\n\t\t<\/div>\n\t\t\n\t\t[vc_column_text woodmart_inline=”no” text_larger=”no”]

    If you compress a forty-five minute conversation down to what a company can actually act on, five things are left.<\/p>

    Five points to remember from this conversation<\/strong><\/p>