Rational design of alternative natural-based coupling media for diagnostic ultrasound imaging: a review

Ultrasound imaging is an indispensable diagnostic and screening tool in healthcare, renowned for its non-invasive nature, real-time visualization, and use of non-ionizing radiation. It plays a vital role in obstetrics and gynaecology by significantly reducing maternal mortality and enhancing patient care. In addition to its use in obstetrics, ultrasound is used to guide biopsies and to evaluate various diseases such as liver cirrhosis, thyroid disorders, and kidney stones. Point-of-care ultrasonography has proven to be increasingly beneficial in low-resource settings. However, the availability and cost of commercial ultrasound gels pose significant challenges. Alternative natural-based gels formulated from locally sourced materials have emerged as viable substitutes. This review critically examines alternative natural-based ultrasound gels, focusing on their physicochemical properties, formulation procedures, and the limitations associated with their use in diagnostic imaging. Furthermore, it presents a rational design approach that methodically selects the ingredients based on their properties and interactions to formulate these gels for imaging applications. This offers a promising pathway for indigenous manufacturers to develop gels that meet ideal performance criteria, ensuring better imaging outcomes and wider acceptability in clinical practice.