From Japan with Love: A Kinder, Cleaner Ultrasound Gel

Japanese researchers have developed a solid, self-moisturizing ultrasound gel made from tamarind seed gum that improves patient comfort without compromising image quality.

Feb 02, 2026

MATERIALS MONDAY || 2026.02.02

In a country known for hospitality and attention to small comforts—warm towels before meals, heated toilet seats in winter—Japanese researchers have turned their attention to an unlikely source of everyday irritation: the cold, sticky, and often smelly gel used during ultrasound exams.

Ultrasound imaging relies on a gel to eliminate air between the probe and the skin, allowing sound waves to pass cleanly into the body. The technology itself is quick, safe, and noninvasive, but the gel has long been a minor annoyance for both patients and clinicians. It can feel unpleasant on the skin, cling to body hair, dry out during longer exams, have an unpleasant odor, and require time and effort to clean away afterward.

Researchers at Kindai University in Osaka now report a simple materials rethink that could make the experience more comfortable without sacrificing image quality. Writing in the journal Scientific Reports, they describe a solid, self-moisturizing ultrasound gel pad made from tamarind seed gum, a natural polysaccharide extracted from the seeds of the tropical tamarind tree.

In a small feasibility study involving just four healthy volunteers, the team, led by Hajime Monzen, a professor in medical physics, tested the solid gel pad against conventional liquid ultrasound gel across a range of common clinical scenarios, including imaging of the carotid artery, thyroid gland, liver, and heart. They found no meaningful differences in image quality between the two materials. Volunteers, however, consistently rated the solid gel as more comfortable than the liquid alternative.

The gel’s performance stems from its carefully tuned composition. Tamarind seed gum is combined with glycerin-rich polyhydric alcohols and water to form a soft, flexible pad that conforms to the skin while remaining stable across typical clinical temperatures.

“Initially, I encountered a gel made only from water and tamarind,” said Monzen, speaking of the serendipitous origin of this research. “The developer explained that the continuous release of moisture was considered a drawback. However, I realized that this property could help prevent drying during ultrasound examinations, reduce the formation of air gaps between the probe and the skin, and thereby maintain stable image quality.”

Photo of the gel being applied. — Sample of the gel pad, which demonstrated improved patient satisfaction but comparable image quality compared to conventional gel. CREDIT: Hajime Monzen, Kindai University, Japan.

That is, unlike earlier solid gel pads, which could crack or dry out unless refrigerated, the new material slowly releases small amounts of moisture—a process known as syneresis—that helps maintain acoustic contact during extended examinations and allows the surface to re-hydrate after brief air exposure.

In tests lasting up to an hour, the researchers observed no drying and no degradation in ultrasound image quality. Volunteers also reported that the solid gel was easier to remove and did not cling to hair, addressing two common complaints associated with liquid gels.

While the study is small and explicitly preliminary, the results strongly point to a practical improvement in a technology used millions of times a day globally. The researchers estimate that the pads could be produced at a cost comparable to current gel usage once cleaning time, preparation, and waste are factored in.

They noted in the paper that feasibility pilot study was conducted as a preliminary investigation of the clinical utility of this new solid gel for US-based diagnosis across all probes for various tissue types and depths, implying global potential. They caution, however, that broader clinical trials and cost-effectiveness studies are still needed before widespread adoption.

The Japan Research Report

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