Flexible and Wearable Ultrasound Device for Medical Applications: A Review on Materials, Structural Designs, and Current Challenges

Flexible and miniaturized devices inspired by the advances in electronic materials, fabrication technologies, and wireless communication have emerged as the next-generation smart devices for medicine and healthcare. One of the most promising applications is the flexible devices and systems for medical ultrasound imaging such as ultrasound transducers. Herein, the recent progress in flexible and wearable devices for medical ultrasound imaging is broadly reviewed, focusing on technologies and potential applications in diagnosis and medical care. First, the progressive prospect of wearable devices is briefed, followed by an introduction of the state-of-art advances in material development and fabrication technologies. Second, the emerging technologies of flexible, thin-film ultrasound transducers is focused in comparison to conventional rigid ultrasound devices. Third, this review highlights recent biomedical applications of the flexible ultrasound transducer. Last but not the least, current challenges and future developments are also discussed from the perspectives of medical ultrasound imaging. The flexible ultrasound transducers with capabilities of mass-fabrication, versatile integration, and on-skin conformability can add unprecedented abilities such as medical imaging and diagnosis to the flexible, skin-wearable devices that are promising to improve the quality of personalized care.