Smart, Flexible, and Future-Ready: Exploring HKUST’s Pioneering Adaptive Structures Research

Boundless: Thanks for your time, Prof. Yang. Was this the first time the International Conference on Adaptive Structures and Technologies, or ICAST, has been held at HKUST?

Prof. Yang: Yes, this is HKUST’s first time hosting ICAST. It is a highly regarded series that began in 1990 as a US–Japan collaboration in Maui, Hawaii. Over the past three decades, ICAST has been hosted across North America, Asia, and Europe. We were delighted to host the 35th edition of this series at HKUST.

Boundless:  What are HKUST’s strengths in adaptive structures and technologies?

Prof. Yang: Several faculty members are working in this field, and more than ten joined the event. Their contributions include piezoelectric materials, ferroelectric effects, composite materials, sensors and actuators, ultrasound, micro-robots, metamaterials, acoustics, vibration, aerospace engineering, 3D printing, and soft matter.

Boundless: Can you briefly introduce any ongoing HKUST research projects on adaptive structures?

Prof. Yang: I’d like to share insights from my research on piezoelectric materials and structures. As I see it, energy is the foundation that makes everything work, so I focus on piezoelectric materials and micro-energy harvesting. Building on my understanding of electromechanical energy conversion, I’ve performed both deep theoretical and hands-on experimental work, combining my knowledge of vibration, electronics, materials, and manufacturing. 

My key results include: (1) developing a new method to design and fabricate 3D interconnected, flexible piezoelectric materials and using them in flexible energy harvesters; (2) studying nonlinear vibration and how circuit coupling affects power-generation efficiency; and (3) working on self-charging face masks to help address COVID-19, translating research into real-world impact beyond the lab.

Boundless: Can you briefly outline some significant examples of the application of adaptive structures that HKUST has helped to implement?

Prof. Yang: In 2024, our team developed a sensor array design technology inspired by the human auditory system. We assigned a unique frequency to each sensor unit and used its signal to modulate the amplitude of the frequency signal. This approach can address traditional issues in sensor array design, including complex wiring, limited reconfigurability, and low damage resistance.

In the same year, we designed a surface-tension-assisted two-step (STATS) processing strategy to fabricate cellular ceramics with programmed 3D cell-based configurations. This strategy overcomes limitations of traditional additive manufacturing (3D printing) to simplify and accelerate production of geometrically complex cellular ceramics.

Moreover, our team developed a novel technique in 2023 to self-assemble a thin layer of amino acids with ordered orientation over a large area, demonstrating high piezoelectric strength. This development makes it more feasible to manufacture biocompatible and biodegradable medical microdevices, such as pacemakers and implantable biosensors, in the near future.

Boundless: What are the major trends in the development of smart materials for adaptive structures? How can sensing technology be integrated into such structures?

Prof. Yang: Major trends include the development of active or field-dependent materials, shape memory materials (alloys, polymers, etc), and ferroelectrics and piezoelectrics.

In recent years, we have also seen significant development of structures and structural systems such as adaptive or smart structural systems; active vibration control and reduction systems; wave control and manipulation systems; leveraging and understanding nonlinearities; passive, semi-active, and active damping systems; and bioinspired structures and robotics.

The scope of sensing technology applications is remarkably broad, spanning aerospace, automotive, and naval activities; damage prognosis and structural health monitoring; medical applications; multifunctional textiles; wearable technologies; and wireless data/power transfer.

For more information on adaptive structures and technologies and Prof. Yang’s research, please refer to Prof. Yang’s Smart Transducers and Vibration Lab (STVL) for details.