Liquid Alloy based Morphing Electronics

From Plant Physiology Monitoring to Habit Manipulation

Significance 

The botany research field has undergone tremendous advancement in recent years. One major focus in this area is creating smart/intelligent systems compatible with plants and their habitats. This enables real-time monitoring of the phycological signals and manipulating the growth habitats of plants for various research applications. Some of the benefits of these applications include improved plant health, better coexistence of plants and animals, and improved agricultural produce that is key to achieving some of the sustainable development goals set by the United Nations.

To date, significant progress has been made in the design and development of epidermal electronics for similar functions in mammals, especially humans. These devices have been successfully interfaced with living mammalian cells, tissues, and organs, but not with epidermal living plants. This can be attributed to several challenges, including the fragile nature of plants that cannot sustain external stimuli, the rapid change in morphology during the growth and development of plants, and the complex plant surfaces at micro-and nano-scale levels. Therefore, it is highly desirable to develop technologies that can effectively overcome these challenges.

Smart systems based on liquid-alloy-based morphing electronics (LAME) have recently emerged as promising solutions for improving plant monitoring and behavioral manipulation. Typically, gallium-based liquid alloys (LA) can be accommodated by plants due to their good electrical conductivity and intrinsically high fluidity properties and are suitable for such applications. Despite the availability of several methods for fabricating LA circuits on three-dimensional (3D) surfaces, most rely on the externally applied pressure and cannot be tolerated by fragile plants. As such, a gentle fabrication process is vital to fabricate compliant electronic systems for such dynamic situations.

Hydroprinting, a gentle surface patterning technology, has been widely used in the decorative industry to provide accurate mapping for 2D and 3D surfaces. Despite the inherent challenges, this technology presents opportunities for developing plant morphing electronics. On this account, a team of researchers at Huazhong University of Science and Technology: Ph.D. students Jiajun Jiang, Shuo Zhang, and Bei Wang, and co-led by Professors Zhigang Wu and Han Ding developed a hydroprinted liquid-alloy-based morphing electronics to monitor physiological and manipulate growth habitats of plants. Specifically, the proposed LAME process targeted fast-growing and tender plants. The study objective was to lay a foundation for the fabrication of new and high-performance morphing electronics. Their research work is currently published in the journal, Small.

In their approach, the authors utilized the innovative and gentle liquid alloy circuit printing process on the highly micro-and nanostructured plant surfaces without carrier films. Apart from the various surfaces of inorganic targeting substrates, a high surface energy liquid was introduced to enhance the pinning of the liquid alloy surface onto the complex plant epidermis. The feasibility of this approach was validated by examining the functionality and compatibility of LAME circuits on the epidermis of the first growing plants.

The authors found out that the proposed morphing electronics could be effectively printed directly onto the complex and fragile 3D surfaces. They were suitable for sensing physiological signals in fast-growing and fragile plants attributed to the excellent compliance, functionality, and deformability of the liquid alloy circuits. This included monitoring of moisture content, stalk length, and manipulating the leaf and sprout orientation. Additionally, the new devices could function as biohybrid to influence the morphological behavior of plants.

In a nutshell, the research team reported the development of hydroprinted LAME for effective and efficient monitoring and manipulation of plants. The proposed approach presented a feasible solution to the inherent limitations of the current technologies. It can be applied to both fast-growing and fragile plants with very minimal disturbance to the plant’s systems. Altogether, the study paves the way for developing high-performance future generation biohybrid plant systems for various applications. In a statement to Advances in Engineering, Professor Zhigang Wu particularly noted that such advanced morphing electronics would not only advance botany research but also positively impact precision agriculture and horticulture.

Liquid Alloy based Morphing Electronics: From Plant Physiology Monitoring to Habit Manipulation - Advances in Engineering

About the author

Zhigang Wu received his PhD in Nanyang Technological University, Singapore. Currently, Dr Wu is a distinguished professor in the school of mechanical science and engineering, Huazhong University of Science and Technology, Wuhan, (HUST). Before joining HUST, Dr Wu was an associate professor in Microsystems Technology, Uppsala University, Sweden. His research focused in soft robotics as well as intelligence soft materials manufacturing. He has published more than 60 papers in the international prestigious journals such as Natl Sci Rev, Adv Mater, Small, Proc. IEEE, Mater Today Phys, Soft Robot and others. Many of them are highlighted as cover articles. According to the database of SCI, the citation numbers is more than 3400 times with an h index is 25. Several papers were respectively selected as hot articles of the year (month), which were cited by Nature, PNAS, Chemical Society Reviews, Angew Chemie Int Ed., and many other leading journals for many times.

His research interests are concentrated on processing and integration technologies of soft electronics and machines for various applications, e.g., in surgical medicine, industrial, life sciences, rehabilitation and home healthcare, and fundamental research and applications in microfluidics for point-of-care healthcare. He also serves as an editorial board member in Journal of Micromechanics and Microengineering, Institute of Physics, UK, and Micromachines, MDPI, and a guest editor in Material Today Physics, Elsevier.

Reference

Jiang, J., Zhang, S., Wang, B., Ding, H., & Wu, Z. (2020). Hydroprinted Liquid‐Alloy‐Based Morphing Electronics for Fast‐Growing/Tender Plants: From Physiology Monitoring to Habit ManipulationSmall, 16(39), 2003833.

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