New biomedical ultrasound technology: Flexible micromachined ultrasound transducer

The new review article unveils the world of flexible micromachined ultrasonic transducers (MUTs), a new technology at the intersection of wearables, ultrasound and MEMS. These cutting-edge devices can offer flexible and user-friendly healthcare solutions, including both piezoelectric (PMUT) and capacitive (CMUT) variants. Flexible MUTs that can conform to the body’s contours can allow for continuous surveillance and target stimulation. This research dives deep into the manufacturing methods of these innovative devices, performance benchmarks, and potential applications.

Ultrasound technology is the basis of medical imaging using rigid probes that generally rely on piezoelectric vibrations in thickness modes. Although effective, these probes have limitations due to manufacturing methods such as mechanical dicing.

To overcome these challenges, alternatives to micromachines such as PMUT and CMUTS have been developed. These devices offer the advantages of small size, reduced power consumption, compatibility with CMOS electronics, and efficient batch manufacturing.

In parallel, a new era of user-friendly alternatives is emerging with the advent of flexible sensor technology. Flexible ultrasound transducers take further away from MEMS advances by introducing the ability to conform to curved surfaces like the human body. Consistent skin contact can reduce diagnostic errors and improve the quality of results. This technique may reveal the need for variability that depends on experienced operators and operators. This is a traditional strict probe requirement used in traditional clinical settings.

However, there remain important hurdles to achieving high-performance material stack designs, developing reliable manufacturing processes, and ensuring seamless integration with existing healthcare systems. Overcoming these challenges is important for the widespread adoption of flexible micromachined ultrasound transducers (MUTs) in the biomedical field.

On January 16, 2025, Ku Leuven’s research team published a detailed review at Microsystems & Nanoengineering, focusing on the development of flexible micromachined ultrasound transducers. This review provides a comprehensive investigation of flexible micromachined ultrasound transducers, an emerging technology in biomedical diagnostics.

The review paper discusses the need for flexibility in ultrasound transducers, highlights potential applications, and explores the possibilities of flexible PMUTs and CMUTs to meet the evolving demands of biomedical research. The author then examines both piezoelectric (PMUT) and capacitive (CMUT) variant manufacturing techniques and details innovative approaches that allow for flexibility without compromising performance.

This study compares key performance parameters such as resonance frequency, sensitivity, and flexibility to reveal the unique benefits of each type. For example, PMUT is known for its low-voltage operation, while CMUT stands out for its ultra-high bandwidth capabilities.

This study highlights the important role of material selection and design optimization in achieving desired performance characteristics. This article also discusses the challenges of integrating these flexible devices with electronic systems and proposes solutions to overcome these obstacles.

This comprehensive analysis not only summarizes the current state of the field, but also outlines the future research directions needed to maximize the potential of flexible MUTs in biomedical applications. It provides valuable insights to researchers, engineers and healthcare professionals.

Sanjog Vilas Joshi, one of the leading authors of this study, stated, “The emergence of flexible micromachined ultrasound transducers is an interesting possibility in integration into biomedical ultrasound, for example, in everyday health care into flexible Muts. Open sex, but remote patient monitoring. To achieve such pioneering goals, technical limitations as outlined in the review must be addressed.

“To achieve this, further investment in R&D in flexible MUT-based technologies is required. In the recent research area of ​​flexible ultrasound, bulk piezoelectric transducers are available to include wearable ultrasound imaging and continuous monitoring. It shows that it is extremely promising in a variety of applications.

“On the other hand, flexible CMUTs are emerging demonstrating proof of the concept of imaging. Flexible PMUTs remain the latest PMUTs with key optimization challenges. Nevertheless, With sustained research, flexible MUTs may bridge the gap with other mature ultrasound modalities. Unlock new opportunities for wearable ultrasound to help diagnose and prevent disease.