At the heart of the challenge is a delicate chemical balancing act. As atmospheric carbon dioxide dissolves into seawater, it forms carbonic acid, which lowers the ocean’s pH and erodes the carbonate chemistry that corals, shellfish and other calcifying organisms depend upon. Ocean carbon dioxide capture exploits a simple principle: if the ocean becomes more alkaline, it can absorb more CO2 from the air and lock it away safely as bicarbonate, one of the most stable and abundant forms of inorganic carbon on Earth. This process, known as ocean alkalinity enhancement, effectively turns the surface ocean into a vast, distributed carbon sink. But adding alkalinity to seawater is not trivial, and doing it in a way that is energy-efficient, scalable and safe has become one of the central engineering puzzles of the emerging carbon removal industry.

One of the most promising approaches relies on electrochemistry, specifically a technique called bipolar membrane electrodialysis. In this system, ion-selective membranes are stacked between two end electrodes, and the arrangement allows operators to split ordinary saltwater into its constituent acid and base. When brine containing sodium chloride flows through the stack, the process generates hydrochloric acid on one side and sodium hydroxide, a strong base, on the other. The elegance of the scheme lies in its product handling: if the hydrochloric acid is kept on land, where it can be stored, neutralized or put to industrial use, and only the sodium hydroxide along with the treated seawater is returned to the ocean, the receiving waters gain a net infusion of alkalinity. That added alkalinity shifts the carbonate equilibrium, allowing the ocean to draw down carbon dioxide from the atmosphere and convert it into dissolved bicarbonate that remains stable for millennia.

This electrochemical pathway has attracted serious commercial interest precisely because it produces what carbon markets call negative emissions, meaning carbon dioxide is durably removed from the atmosphere rather than merely avoided. Companies pursuing net-zero targets increasingly rely on such carbon removal credits to offset their residual emissions, and ocean alkalinity enhancement is widely regarded as one of the largest-capacity avenues available, given the sheer scale of the world’s oceans. Yet the technology has been held back by a deceptively mundane problem: what flows into the reactor matters just as much as what flows out.

Seawater, and many other brine streams that might feed these systems, contains divalent cations, most notably calcium and magnesium ions, alongside the sodium and chloride that the process is designed to split. When these divalent ions encounter the high-pH conditions created at the base-producing side of a bipolar membrane stack, they precipitate as solid calcium and magnesium compounds that coat the membranes in a crust known as scale. The consequences are cascading. Scaled membranes lose their ion-selective efficiency, forcing the system to push harder and consume more electricity to achieve the same output. Over time, the deposits shorten membrane lifetime, increasing maintenance frequency and replacement costs. The conventional answer has been water softening pretreatment, in which the incoming seawater is stripped of calcium and magnesium before it ever reaches the electrodialysis unit. While effective, such pretreatment adds significant capital and operating expense, undermining the economic case for the entire carbon removal operation and eroding the value proposition of the resulting carbon credits.

The Stony Brook researchers behind the new method have essentially designed around this bottleneck. Their technology enables electrochemical enhancement of ocean alkalinity without any pretreatment of the incoming seawater at all. By rethinking how the electrochemical system handles brine streams laden with divalent cations, the researchers have created a process that tolerates raw seawater directly, sidestepping the water softening infrastructure that previous designs demanded. According to the announcement from the Research Foundation for SUNY, the result is a system that produces negative emission carbon offsets of very high quality at a substantially reduced cost, simply because the most expensive upstream step has been engineered out of existence. The advantages claimed for the approach are straightforward and commercially significant: it is cheaper, more energy efficient, and requires no expensive water softening pretreatment.

The implications ripple across both the carbon markets and the broader climate technology landscape. Carbon offset buyers, including corporations striving to meet net-zero commitments, place a premium on removal credits that are durable, verifiable and cost-competitive. Ocean alkalinity enhancement already offers exceptional permanence, since bicarbonate dissolved in seawater represents one of the most long-lived forms of carbon storage known. By cutting costs at the front end, the Stony Brook method could help push the price of these high-quality ocean-based offsets toward levels that make them viable at gigatonne scale, a threshold that analysts consider essential if carbon removal is to play a meaningful role in stabilizing the global climate. Cheaper alkalinity generation also strengthens the second major application of the technology: mitigating ocean acidification directly, without necessarily framing it as a carbon market product at all.

Ocean acidification itself is a mounting crisis. Since the industrial revolution, the average surface ocean pH has dropped measurably as the sea has absorbed roughly a quarter to a third of anthropogenic CO2 emissions. The consequences have been documented across coral reefs, oyster hatcheries, pteropods and other calcifying organisms whose shells and skeletons become harder to build in increasingly acidic waters. A technology that adds alkalinity to coastal waters and open ocean regions simultaneously addresses this chemical stress and harvests the carbon removal benefit, a dual function that distinguishes ocean alkalinity enhancement from many other carbon removal approaches. In regions where fisheries, aquaculture and reef ecosystems are economically vital, localized deployment of alkalinity-enhancing electrochemical systems could offer both environmental resilience and revenue through carbon credit sales.

The scientific pedigree of the work reflects the growing maturity of the carbon removal field. Stony Brook University, a flagship research institution within the SUNY system, has become an active hub for climate and energy innovation, and the new method is protected under intellectual property identified in the licensing announcement. The Research Foundation for the State University of New York, the nation’s largest research foundation supporting the nation’s largest public university system, is actively seeking development partners, commercial partners and licensees to translate the laboratory advance into deployed systems. The foundation describes a broad portfolio of SUNY-led research spanning artificial intelligence for the public good, quantum technologies, next-generation semiconductors, biotechnology and medicine, and energy and climate solutions, with system-wide research expenditures approaching 1.5 billion dollars in fiscal year 2025.

For the carbon removal industry, the timing of the announcement is notable. As voluntary and compliance carbon markets mature, buyers are demanding higher fidelity in the offsets they purchase, favoring durable removal over avoidance-based credits. Electrochemical ocean alkalinity enhancement, with its well-understood chemistry and measurable inputs and outputs, is well positioned to meet rigorous monitoring, reporting and verification standards. The obstacle has always been cost, and the pretreatment bottleneck has been a substantial contributor. If the Stony Brook design performs as described at industrial scale, it could remove one of the largest cost wedges standing between laboratory demonstration and commercial deployment, accelerating a technology class that many climate analysts view as indispensable to achieving deep decarbonization.

The broader lesson of the advance may be as important as the technology itself. In the race to scale carbon removal, progress often comes not from exotic new chemistry but from eliminating the hidden costs and fragilities that make promising concepts uneconomic in practice. Water softening pretreatment is exactly the kind of unglamorous engineering detail that determines whether a climate technology remains a paper exercise or becomes infrastructure. By designing a bipolar membrane electrodialysis system that thrives on untreated seawater, the Stony Brook researchers have addressed one of those decisive details. The ocean, meanwhile, stands ready. Every unit of alkalinity added is an invitation for the sea to take up more carbon dioxide and, in doing so, to heal a little of the acidification that a warming world has inflicted upon it. What remains now is the work of scaling, partnering and commercializing, and the SUNY licensing announcement signals that the researchers and their institution intend to see this chemistry leave the laboratory and reach the sea.

Traditionally, THz imaging techniques have primarily exploited contrasts based on water content differences to distinguish healthy from diseased tissues. While this approach has been somewhat effective, it falls short when confronting the intricate heterogeneity found in pathological conditions like cancer and burn injuries. The reliance on hydration levels oversimplifies tissue complexity, often masking crucial microstructural changes that could serve as reliable biomarkers of disease progression. Polarimetric measurements of THz waves—analyzing changes in wave polarization after interaction with tissue—offer a promising alternative, capable of capturing nuanced architectural features. However, the biophysical mechanisms underlying these polarization changes remained elusive until the recent computational explorations provided new clarity.

The research team harnessed Monte Carlo simulations—a statistical technique well-suited for modeling complex scattering phenomena—to explore how THz waves interact with microscopic spherical particles embedded in strongly absorbing biological media. These particles effectively represent key pathological structures found in diseased tissue, such as clusters of tumor cells or the damaged microstructures seen in burns, including the destruction of hair follicles and sweat glands. The simulations revealed that both the intensity of diffusely scattered THz light and its degree of polarization exhibit predictable variations depending on the size and concentration of these scatterers. Intriguingly, these signatures enabled the characterization of tissue polarimetric properties through a single polarization measurement, streamlining what previously demanded multiple, complex measurements.

Complementing their simulations, the team manufactured tissue phantoms composed of gelatin imbued with polypropylene spheres varying in size to emulate the optical properties and scattering behavior of real tissue. These experimental validations confirmed the computational predictions: larger spheres consistently yielded stronger scattered light intensity and displayed characteristic polarization dips at specific terahertz frequencies. This frequency-dependent polarimetric response sets a foundation for non-destructive, detailed tissue assessment, which could dramatically enhance diagnostic accuracy in clinical settings.

The researchers further demonstrated the clinical relevance of their approach by applying THz polarimetric imaging to porcine skin samples with induced burns, uncovering distinctive contrast between injured and healthy tissue zones. This capability suggests that THz scattering and polarimetric measurements can serve as sensitive indicators of tissue damage, holding promise for monitoring wound healing and assessing burn severity without invasive biopsies or staining—techniques currently standard in medicine but often time-consuming and resource-intensive.

Importantly, the study’s findings extend beyond burn diagnostics, offering new avenues for oncological applications. Early detection of tumor budding, where small clusters of malignant cells dissociate from the primary tumor mass, is critical for prognosis and treatment planning. Traditional detection relies on biopsy coupled with histological staining, procedures that are not only invasive but also subject to sampling errors. THz polarimetric imaging’s ability to visualize microscopic clusters through inherent tissue scattering properties presents an innovative, potentially faster diagnostic pathway, bypassing lengthy sample preparation while maintaining high sensitivity.

From a technical perspective, the study underscores the power of combining advanced computational physics with experimental optics. Monte Carlo models account for the diffuse, multiple scattering environments typical of biological tissues, a challenging scenario that hampers many conventional imaging techniques. By simulating polarized THz light’s complex interactions with tissue phantoms mimicking realistic absorption and scattering conditions, the researchers not only demystified the origins of polarimetric signals but also established quantifiable relationships between tissue microstructure and measurable optical parameters.

Looking forward, the research group plans to expand their investigations into actual cancer tissue samples, deepening the understanding of how THz polarimetric signals correlate with diverse pathological features. The development of broadband THz systems will further enable resolution of even smaller tissue structures—potentially as minute as 10 to 30 micrometers—thereby broadening the scope of detectible disease-related changes. Such advances could usher in a new paradigm of label-free, real-time tissue characterization with broad implications for early diagnosis and personalized medicine.

The implications for the medical field are profound: by offering a non-invasive, rapid, and sensitive diagnostic method, THz polarimetric imaging could reduce dependency on biopsies, lower healthcare costs, and increase patient comfort. Moreover, as THz technology matures, integration into clinical workflows might enable continuous, bedside monitoring of disease progression or therapeutic response, a feat still unachievable with many existing imaging modalities.

This study marks a significant milestone in medical optics, bridging theoretical physics, computational modeling, and experimental validation to harness the full diagnostic potential of terahertz waves. As the field moves forward, collaboration among optical physicists, engineers, and clinicians will be essential to translate these promising discoveries into effective tools for daily medical practice, potentially transforming cancer detection, burn assessment, and beyond.

In summary, the research lays out a comprehensive framework for understanding and exploiting THz Mie scattering and polarization phenomena in tissues, backed by rigorous simulation and corroborated through experimental imaging. By illuminating the subtle, yet diagnostically meaningful, variations in tissue microstructure through a novel optical window, this work sets the stage for a new generation of medical imaging technologies with remarkable sensitivity, specificity, and clinical impact.

Subject of Research: Human tissue samples
Article Title: Terahertz Mie scattering in tissue: diffuse polarimetric imaging and Monte Carlo validation in highly attenuating media models
News Publication Date: 4-Jun-2025
Web References: https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-30/issue-06/066001/Terahertz-Mie-scattering-in-tissue–diffuse-polarimetric-imaging-and/10.1117/1.JBO.30.6.066001.full
References: E. Heller et al., “Terahertz Mie scattering in tissue: diffuse polarimetric imaging and Monte Carlo validation in highly attenuating media models,” J. Biomed. Opt. 30(6), 066001 (2025). DOI: 10.1117/1.JBO.30.6.066001
Image Credits: Heller et al., doi 10.1117/1.JBO.30.6.066001

Keywords

Imaging, Oncology, Applied optics, Medical tests, Tissue damage