Breast cancer is a long-lasting global health challenge, and its early detection plays an important role in improving survival rates. Ultrasound is one of the most common methods of medical imaging for breast cancer, as it uses high-frequency sound waves to image the body's internal structures. However, current ultrasound methods have limitations, especially when encountering the complex and variable geometries of the breast. We envision a future in which we can detect breast cancer with a simple, user-friendly, at-home use wearable patch, transforming the possibilities for its early detection and increasing the survival rate to up to 98%. 

 

At present, the wide deployment of ultrasound for disease detection and monitoring has been limited by fixed transducer shapes. A transducer is the part of the ultrasound device that is placed on the body, as it emits sound waves and receives the echoes to create an image. This fixed transducer geometry is generally considered a requirement for image reconstruction. However, the curvature of body surfaces is not fixed, which necessitates the application of transducer pressure by an operator during imaging. This compression-based process of imaging requires skill, which increases the variability of results between operators and makes it incompatible with wearable technology. Additionally, it is impractical for existing planar and bulky ultrasound transducers to maintain sufficient contact to image extensively over curved surfaces like the breast. To address these challenges, we have developed a conformable, wearable ultrasound patch that eliminates the need for the operator-applied pressure with a transducer, as it maintains consistent and close contact over large-area, curvilinear soft tissue. 

 

Our new conformable Ultrasound BreastPatch (cUSBr-Patch) makes several novel scientific and engineering contributions. First, it introduces a large-area, conformable transducer design that is flexible to conform to the breast’s shape. The transducer is phased array, meaning that it contains multiple small elements that can be controlled independently to focus the ultrasound waves more precisely on the breast area. By embedding these piezoelectric elements into a soft material, we ensure consistent contact with the skin for clear imaging as the ultrasound patch adapts to the shape of the soft tissue target (in this case, the breast). Moreover, the design of this patch is inspired by the honeycomb structure found in nature. This patch design is composed of a soft fabric bra as an intermediary layer, a honeycomb patch outer layer for scanning guidance, and a tracker attached to the ultrasound array for rotation and handling. This honeycomb design directly guides the user for scanning, resulting in consistent and reliable imaging, in addition to easy use. The design also allows for 360-degree rotation at all points, greatly increasing its range of motion. 

 

We achieved a high contrast resolution of ~3dB by using a novel piezoelectric crystal, which generates an electrical charge when pressure is applied, alongside this nature-inspired honeycomb patch design. Our in vitro experiments revealed that we captured details as small as 0.25 mm from top to bottom (axial) and 1.0 mm from side to side (lateral) at a depth of 30 mm. Using this prototype with a commercial ultrasound imaging system, we successfully detected a small cyst (of about 3 mm) in the breast of a female subject with a history of breast anomalies. This makes the cUSBr-Patch suitable for early breast cancer screening, in which lesion dimensions do not exceed 20 mm. The honeycomb design allows for imaging without a skilled operator, in addition to creating repeatable imaging positions for reliable breast tissue screening in long-term monitoring. 

 

Our cUSBr-Patch will advance the understanding of soft tissue imaging by enabling an ultrasound technology that can be scaled up in size to any human body part. Compared to current diagnostic ultrasound, our patch is operator-independent, allows for standardized and reproducible image acquisition, requires less technician time and effort, and is conformable over the entire breast. 

 

Future development of this system would allow patients to self-screen daily, record historical sonographic data, and send their data profiles to medical practitioners—without needing medical appointments. Integrated AI for imaging analysis could investigate collected images, aid in diagnosis, and predict trends. Complementing mammographic imaging with automated analysis would optimize the use of scarce breast cancer care resources. 

 

In conclusion, our cUSBr-Patch represents a revolutionary step in medical diagnostics, offering a cost-effective, accessible, and user-friendly wearable ultrasound tool. Not only will it save time for doctors and augment standard technical analysis, but it also provides a practical solution to the widespread challenges of accessibility, cost, and infrastructure limitations, particularly in developing nations.